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RFC 6917 - Media Resource Brokering


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Internet Engineering Task Force (IETF)                        C. Boulton
Request for Comments: 6917                               NS-Technologies
Category: Standards Track                                     L. Miniero
ISSN: 2070-1721                                                 Meetecho
                                                               G. Munson
                                                                    AT&T
                                                              April 2013

                        Media Resource Brokering

Abstract

   The MediaCtrl working group in the IETF has proposed an architecture
   for controlling media services.  The Session Initiation Protocol
   (SIP) is used as the signaling protocol that provides many inherent
   capabilities for message routing.  In addition to such signaling
   properties, a need exists for intelligent, application-level media
   service selection based on non-static signaling properties.  This is
   especially true when considered in conjunction with deployment
   architectures that include 1:M and M:N combinations of Application
   Servers and Media Servers.  This document introduces a Media Resource
   Broker (MRB) entity, which manages the availability of Media Servers
   and the media resource demands of Application Servers.  The document
   includes potential deployment options for an MRB and appropriate
   interfaces to Application Servers and Media Servers.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6917.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Conventions and Terminology .....................................6
   3. Problem Discussion ..............................................6
   4. Deployment Scenario Options .....................................7
      4.1. Query MRB ..................................................8
           4.1.1. Hybrid Query MRB ....................................9
      4.2. In-Line MRB ...............................................11
   5. MRB Interface Definitions ......................................12
      5.1. Media Server Resource Publish Interface ...................12
           5.1.1. Control Package Definition .........................13
           5.1.2. Element Definitions ................................15
           5.1.3. <mrbrequest> .......................................15
           5.1.4. <mrbresponse> ......................................17
           5.1.5. <mrbnotification> ..................................19
      5.2. Media Service Resource Consumer Interface .................30
           5.2.1. Query Mode/HTTP Consumer Interface Usage ...........31
           5.2.2. In-Line Aware Mode/SIP Consumer Interface Usage ....32
           5.2.3. Consumer Interface Lease Mechanism .................35
           5.2.4. <mrbconsumer> ......................................38
           5.2.5. Media Service Resource Request .....................39
           5.2.6. Media Service Resource Response ....................51
      5.3. In-Line Unaware MRB Interface .............................54
   6. MRB Acting as a B2BUA ..........................................54
   7. Multimodal MRB Implementations .................................55
   8. Relative Merits of Query Mode, IAMM, and IUMM ..................56
   9. Examples .......................................................58
      9.1. Publish Example ...........................................58
      9.2. Consumer Examples .........................................64
           9.2.1. Query Example ......................................64
           9.2.2. IAMM Examples ......................................68
   10. Media Service Resource Publisher Interface XML Schema .........83

   11. Media Service Resource Consumer Interface XML Schema .........106
   12. Security Considerations ......................................127
   13. IANA Considerations ..........................................130
      13.1. Media Control Channel Framework Package Registration ....130
      13.2. application/mrb-publish+xml Media Type ..................130
      13.3. application/mrb-consumer+xml Media Type .................131
      13.4. URN Sub-Namespace Registration for mrb-publish ..........132
      13.5. URN Sub-Namespace Registration for mrb-consumer .........132
      13.6. XML Schema Registration for mrb-publish .................132
      13.7. XML Schema Registration for mrb-consumer ................133
   14. Acknowledgements .............................................133
   15. References ...................................................133
      15.1. Normative References ....................................133
      15.2. Informative References ..................................135

1.  Introduction

   As IP-based multimedia infrastructures mature, the complexity and
   demands from deployments increase.  Such complexity will result in a
   wide variety of capabilities from a range of vendors that should all
   be interoperable using the architecture and protocols produced by the
   MediaCtrl working group.  It should be possible for a controlling
   entity to be assisted in Media Server selection so that the most
   appropriate resource is selected for a particular operation.  The
   importance increases when one introduces a flexible level of
   deployment scenarios, as specified in RFC 5167 [RFC5167] and RFC 5567
   [RFC5567].  These documents make statements like "it should be
   possible to have a many-to-many relationship between Application
   Servers and Media Servers that use this protocol".  This leads to the
   following deployment architectures being possible when considering
   media resources, to provide what can be effectively described as
   media resource brokering.

   The simplest deployment view is illustrated in Figure 1.

   +---+-----+---+                         +---+-----+---+
   | Application |                         |    Media    |
   |   Server    |<-------MS Control------>|    Server   |
   +-------------+                         +-------------+

                       Figure 1: Basic Architecture

   This simply involves a single Application Server and Media Server.
   Expanding on this view, it is also possible for an Application Server
   to control multiple (greater than 1) Media Server instances at any
   one time.  This deployment view is illustrated in Figure 2.
   Typically, such architectures are associated with application logic
   that requires high-demand media services.  It is more than possible

   that each Media Server possesses a different media capability set.
   Media Servers may offer different media services as specified in the
   MediaCtrl architecture document [RFC5567].  A Media Server may have
   similar media functionality but may have different capacity or media
   codec support.

                                           +---+-----+---+
                                           |    Media    |
                                    +----->|    Server   |
                                    |      +-------------+
                                    |
   +---+-----+---+                  |      +---+-----+---+
   | Application |                  |      |    Media    |
   |   Server    |<--MS Control-----+----->|    Server   |
   +-------------+                  |      +-------------+
                                    |
                                    |      +---+-----+---+
                                    +----->|    Media    |
                                           |    Server   |
                                           +-------------+

                     Figure 2: Multiple Media Servers

   Figure 3 conveys the opposite view to that in Figure 2.  In this
   model, there are a number of (greater than 1) Application Servers,
   possibly supporting dissimilar applications, controlling a single
   Media Server.  Typically, such architectures are associated with
   application logic that requires low-demand media services.

   +---+-----+---+
   | Application |
   |   Server    |<-----+
   +-------------+      |
                        |
   +---+-----+---+      |                  +---+-----+---+
   | Application |      |                  |    Media    |
   |   Server    |<-----+-----MS Control-->|    Server   |
   +-------------+      |                  +-------------+
                        |
   +---+-----+---+      |
   | Application |      |
   |   Server    |<-----+
   +-------------+

                  Figure 3: Multiple Application Servers

   The final deployment view is the most complex (Figure 4).  In this
   model (M:N), there exist any number of Application Servers and any
   number of Media Servers.  It is again possible in this model that
   Media Servers might not be homogeneous, and they might have different
   capability sets and capacities.

   +---+-----+---+                         +---+-----+---+
   | Application |                         |    Media    |
   |   Server    |<-----+            +---->|    Server   |
   +-------------+      |            |     +-------------+
                        |            |
   +---+-----+---+      |            |     +---+-----+---+
   | Application |      |            |     |    Media    |
   |   Server    |<-----+-MS Control-+---->|    Server   |
   +-------------+      |            |     +-------------+
                        |            |
   +---+-----+---+      |            |     +---+-----+---+
   | Application |      |            +---->|    Media    |
   |   Server    |<-----+                  |    Server   |
   +-------------+                         +---+-----+---+

                    Figure 4: Many-to-Many Architecture

   The remaining sections in this specification will focus on a new
   entity called a Media Resource Broker (MRB), which can be utilized in
   the deployment architectures described previously in this section.
   The MRB entity provides the ability to obtain media resource
   information and appropriately allocate (broker) on behalf of client
   applications.

   The high-level deployment options discussed in this section rely on
   network architecture and policy to prohibit inappropriate use.  Such
   policies are out of scope for this document.

   This document will take a look at the specific problem areas related
   to such deployment architectures.  It is recognized that the
   solutions proposed in this document should be equally adaptable to
   all of the previously described deployment models.  It is also
   recognized that the solution is far more relevant to some of the
   previously discussed deployment models and can almost be viewed as
   redundant on others.

2.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   This document inherits terminology proposed in RFC 5567 [RFC5567] and
   in "Media Control Channel Framework" [RFC6230].  In addition, the
   following terms are defined for use in this document and for use in
   the context of the MediaCtrl working group in the IETF:

   Media Resource Broker (MRB):  A logical entity that is responsible
      for both collection of appropriate published Media Server (MS)
      information and selecting appropriate Media Server resources on
      behalf of consuming entities.

   Query MRB:  An instantiation of an MRB (see previous definition) that
      provides an interface for an Application Server to retrieve the
      address of an appropriate Media Server.  The result returned to
      the Application Server can be influenced by information contained
      in the query request.

   In-line MRB:  An instantiation of an MRB (see previous definition)
      that directly receives requests on the signaling path.  There is
      no separate query.

   CFW:  Media Control Channel Framework, as specified in [RFC6230].

   Within the context of In-line MRBs, additional terms are defined:

   In-line Aware MRB Mode (IAMM):  Defined in Section 5.2.2.1.

   In-line Unaware MRB Mode (IUMM):  Defined in Section 5.3.

   The document will often specify when a specific identifier in a
   protocol message needs to be unique.  Unless stated otherwise, such
   uniqueness will always be within the scope of the Media Servers
   controlled by the same MRB.  The interaction between different MRB
   instances, e.g., the partitioning of a logical MRB, is out of scope
   for this document.

3.  Problem Discussion

   As discussed in Section 1, a goal of the MediaCtrl working group is
   to produce a solution that will service a wide variety of deployment
   architectures.  Such architectures range from the simplest 1:1
   relationship between Media Servers and Application Servers to
   potentially linearly scaling 1:M, M:1, and M:N deployments.

   Managing such deployments is itself non-trivial for the proposed
   solution until an additional number of factors that increase
   complexity are included in the equation.  As Media Servers evolve, it
   must be taken into consideration that, where many can exist in a
   deployment, they may not have been produced by the same vendor and
   may not have the same capability set.  It should be possible for an
   Application Server that exists in a deployment to select a media
   service based on a common, appropriate capability set.  In
   conjunction with capabilities, it is also important to take available
   resources into consideration.  The ability to select an appropriate
   media service function is an extremely useful feature but becomes
   even more powerful when considered with available resources for
   servicing a request.

   In conclusion, the intention is to create a toolkit that allows
   MediaCtrl deployments to effectively utilize the available media
   resources.  It should be noted that in the simplest deployments where
   only a single Media Server exists, an MRB function is probably not
   required.  Only a single capability set exists, and resource
   availability can be handled using the appropriate underlying
   signaling, e.g., SIP response.  This document does not prohibit such
   uses of an MRB; it simply provides the tools for various entities to
   interact where appropriate.  It is also worth noting that the
   functions specified in this document aim to provide a 'best effort'
   view of media resources at the time of request for initial Media
   Server routing decisions.  Any dramatic change in media capabilities
   or capacity after a request has taken place should be handled by the
   underlying protocol.

   It should be noted that there may be additional information that is
   desirable for the MRB to have for purposes of selecting a Media
   Server resource, such as resource allocation rules across different
   applications, planned or unplanned downtime of Media Server
   resources, the planned addition of future Media Server resources, or
   Media Server resource capacity models.  How the MRB acquires such
   information is outside the scope of this document.  The specific
   techniques used for selecting an appropriate media resource by an MRB
   is also outside the scope of this document.

4.  Deployment Scenario Options

   Research into media resource brokering concluded that a couple of
   high-level models provided an appropriate level of flexibility.  The
   general principles of "in-line" and "query" MRB concepts are
   discussed in the rest of this section.  It should be noted that while
   the interfaces are different, they both use common underlying
   mechanisms defined in this specification.

4.1.  Query MRB

   The "Query" model for MRB interactions provides the ability for a
   client of media services (for example, an Application Server) to
   "ask" an MRB for an appropriate Media Server, as illustrated in
   Figure 5.

                        +---+-----+---+
          +------------>|     MRB     |<----------+----<-----+---+
          |             +-------------+        (1)|          |   |
          |                                       |          |   |
          |(2)                             +---+--+--+---+   |   |
          |                                |    Media    |   |   |
          |                          +---->|    Server   |   |   |
          |                          |     +-------------+   |   |
          |                          |                    (1)|   |
   +---+--+--+---+                   |     +---+-----+---+   |   |
   | Application |                   |     |    Media    |   |   |
   |   Server    |<-----+-MS Control-+---->|    Server   |->-+   |
   +-------------+          (3)      |     +-------------+       |
                                     |                           |
                                     |     +---+-----+---+    (1)|
                                     +---->|    Media    |       |
                                           |    Server   |--->---+
                                           +---+-----+---+

                            Figure 5: Query MRB

   In this deployment, the Media Servers use the Media Server Resource
   Publish interface, as discussed in Section 5.1, to convey capability
   sets as well as resource information.  This is depicted by (1) in
   Figure 5.  It is then the MRB's responsibility to accumulate all
   appropriate information relating to media services in the logical
   deployment cluster.  The Application Server (or other media services
   client) is then able to query the MRB for an appropriate resource (as
   identified by (2) in Figure 5).  Such a query would carry specific
   information related to the media service required and enable the MRB
   to provide increased accuracy in its response.  This particular
   interface is discussed in "Media Service Resource Consumer Interface"
   (Section 5.2).  The Application Server is then able to direct control
   commands (for example, create a conference) and media dialogs to the
   appropriate Media Server, as shown by (3) in Figure 5.  Additionally,
   with Query mode, the MRB is not directly in the signaling path
   between the Application Server and the selected Media Server
   resource.

4.1.1.  Hybrid Query MRB

   As mentioned previously, it is the intention that a toolkit is
   provided for MRB functionality within a MediaCtrl architecture.  It
   is expected that in specific deployment scenarios the role of the MRB
   might be co-hosted as a hybrid logical entity with an Application
   Server, as shown in Figure 6.

          +------------<----------------<---------+----<-----+---+
          |                     (1)               |          |   |
          |                                       |          |   |
          |                                +---+--+--+---+   |   |
          |                                |    Media    |   |   |
          V                          +---->|    Server   |   |   |
   +------+------+                   |     +-------------+   |   |
   |     MRB     |                   |                       |   |
   +---+--+--+---+                   |     +---+-----+---+   |   |
   | Application |                   |     |    Media    |   |   |
   |   Server    |<-----+-MS Control-+---->|    Server   |->-+   |
   +-------------+                   |     +-------------+       |
                                     |                           |
                                     |     +---+-----+---+       |
                                     +---->|    Media    |       |
                                           |    Server   |--->---+
                                           +---+-----+---+

          Figure 6: Hybrid Query MRB - Application Server Hosted

   This diagram is identical to that in Figure 5 with the exception that
   the MRB is now hosted on the Application Server.  The Media Server
   Publish interface is still being used to accumulate resource
   information at the MRB, but as it is co-hosted on the Application
   Server, the Media Server Consumer interface has collapsed.  It might
   still exist within the Application Server/MRB interaction, but this
   is an implementation issue.  This type of deployment suits a single
   Application Server environment, but it should be noted that a Media
   Server Consumer interface could then be offered from the hybrid if
   required.

   In a similar manner, the Media Server could also act as a hybrid for
   the deployment cluster, as illustrated in Figure 7.

                                   (1)                 +---+-----+---+
   +---+---+------------->---------------->----------->|     MRB     |
   |   |   |   +---+--+--+---+                         +---+-----+---+
   |   |   +-<-| Application |                         |    Media    |
   |   |       |   Server    |<--+-MS Control-+------->|    Server   |
   |   |       +-------------+                   |     +-------------+
   |   |                                         |
   |   |       +---+--+--+---+                   |
   |   +---<---| Application |                   |
   |           |   Server    |<--+-MS Control-+--+
   |           +-------------+                   |
   |                                             |
   |           +---+--+--+---+                   |
   +---<-------| Application |                   |
               |   Server    |<--+-MS Control-+--+
               +-------------+

                  Figure 7: Hybrid Query MRB - MS Hosted

   In this example, the MRB has collapsed and is co-hosted by the Media
   Server.  The Media Server Consumer interface is still available to
   the Application Servers (1) to query Media Server resources.  The
   Media Server Publish interface has collapsed onto the Media Server.
   It might still exist within the Media Server/MRB interaction, but
   this is an implementation issue.  This type of deployment suits a
   single Media Server environment, but it should be noted that a Media
   Server Publish interface could then be offered from the hybrid if
   required.  A typical use case scenario for such a topology would be a
   single Media Server representing a pool of MSs in a cluster.  In this
   case, the MRB would actually be handling a cluster of Media Servers,
   rather than one.

4.2.  In-Line MRB

   The "In-line" MRB is architecturally different from the "Query" model
   discussed in the previous section.  The concept of a separate query
   disappears.  The client of the MRB simply uses the media resource
   control and media dialog signaling to involve the MRB.  This type of
   deployment is illustrated in Figure 8.

                               +-------<----------+----<-------+---+
                               |                  | (1)        |   |
                               |                  |            |   |
                               |             +---+--+--+---+   |   |
                               |             |    Media    |   |   |
                               |     +------>|    Server   |   |   |
                               |     |(3)    +-------------+   |   |
                               |     |                      (1)|   |
   +---+--+--+---+             |     |       +---+-----+---+   |   |
   | Application |  (2) +---+--V--+---+  (3) |    Media    |   |   |
   |   Server    |----->|     MRB     |----->|    Server   |->-+   |
   +-------------+      +---+-----+---+      +-------------+       |
                                     |                             |
                                     |   (3) +---+-----+---+    (1)|
                                     +------>|    Media    |       |
                                             |    Server   |--->---+
                                             +---+-----+---+

                           Figure 8: In-Line MRB

   The Media Servers still use the Media Server Publish interface to
   convey capabilities and resources to the MRB, as illustrated by (1).
   The Media Server Control Channels (and media dialogs as well, if
   required) are sent to the MRB (2), which then selects an appropriate
   Media Server (3) and remains in the signaling path between the
   Application Server and the Media Server resources.

   The In-line MRB can be split into two distinct logical roles that can
   be applied on a per-request basis.  They are:

   In-line Unaware MRB Mode (IUMM):  Allows an MRB to act on behalf of
      clients requiring media services who are not aware of an MRB or
      its operation.  In this case, the Application Server does not
      provide explicit information on the kind of Media Server resource
      it needs (as in Section 5.2), and the MRB is left to deduce it by
      potentially inspecting other information in the request from the
      Application Server (for example, Session Description Protocol
      (SDP) content, or address of the requesting Application Server, or
      additional Request-URI parameters as per RFC 4240 [RFC4240]).

   In-line Aware MRB Mode (IAMM):  Allows an MRB to act on behalf of
      clients requiring media services who are aware of an MRB and its
      operation.  In particular, it allows the Application Server to
      explicitly convey matching characteristics to those provided by
      Media Servers, as does the Query MRB mode (as in Section 5.2).

   In either of the previously described roles, signaling as specified
   by the Media Control Channel Framework ([RFC6230]) would be involved,
   and the MRB would deduce that the selected Media Server resources are
   no longer needed when the Application Server or Media Server
   terminates the corresponding SIP dialog.  The two modes are discussed
   in more detail in Section 5.3.

5.  MRB Interface Definitions

   The intention of this specification is to provide a toolkit for a
   variety of deployment architectures where media resource brokering
   can take place.  Two main interfaces are required to support the
   differing requirements.  The two interfaces are described in the
   remainder of this section and have been named the Media Server
   Resource Publish and Media Server Resource Consumer interfaces.

   It is beyond the scope of this document to define exactly how to
   construct an MRB using the interfaces described.  It is, however,
   important that the two interfaces are complimentary so that
   development of appropriate MRB functionality is supported.

5.1.  Media Server Resource Publish Interface

   The Media Server Resource Publish interface is responsible for
   providing an MRB with appropriate Media Server resource information.
   As such, this interface is assumed to provide both general and
   specific details related to Media Server resources.  This information
   needs to be conveyed using an industry standard mechanism to provide
   increased levels of adoption and interoperability.  A Control Package
   for the Media Control Channel Framework will be specified to fulfill
   this interface requirement.  It provides an establishment and
   monitoring mechanism to enable a Media Server to report appropriate
   statistics to an MRB.  The Publish interface is used with both the
   Query mode and In-line mode of MRB operation.

   As already discussed in Section 1, the MRB view of Media Server
   resource availability will in reality be approximate -- i.e., partial
   and imperfect.  The MRB Publish interface does not provide an
   exhaustive view of current Media Server resource consumption; the
   Media Server may in some cases provide a best-effort computed view of
   resource consumption parameters conveyed in the Publish interface
   (e.g., Digital Signal Processors (DSPs) with a fixed number of

   streams versus Graphics Processing Units (GPUs) with CPU
   availability).  Media resource information may only be reported
   periodically over the Publish interface to an MRB.

   It is also worth noting that while the scope of the MRB is in
   providing interested Application Servers with the available
   resources, the MRB also allows for the retrieval of information about
   consumed resources.  While this is of course a relevant piece of
   information (e.g., for monitoring purposes), such functionality
   inevitably raises security considerations, and implementations should
   take this into account.  See Section 12 for more details.

   The MRB Publish interface uses the Media Control Channel Framework
   ([RFC6230]) as the basis for interaction between a Media Server and
   an MRB.  The Media Control Channel Framework uses an extension
   mechanism to allow specific usages that are known as Control
   Packages.  Section 5.1.1 defines the Control Package that MUST be
   implemented by any Media Server wanting to interact with an MRB
   entity.

5.1.1.  Control Package Definition

   This section fulfills the requirement for information that must be
   specified during the definition of a Control Framework package, as
   detailed in Section 8 of [RFC6230].

5.1.1.1.  Control Package Name

   The Media Channel Control Framework requires a Control Package
   definition to specify and register a unique name and version.

   The name and version of this Control Package is "mrb-publish/1.0".

5.1.1.2.  Framework Message Usage

   The MRB Publish interface allows a Media Server to convey available
   capabilities and resources to an MRB entity.

   This package defines XML elements in Section 5.1.2 and provides an
   XML schema in Section 10.

   The XML elements in this package are split into requests, responses,
   and event notifications.  Requests are carried in CONTROL message
   bodies; the <mrbrequest> element is defined as a package request.
   This request can be used for creating new subscriptions and updating/
   removing existing subscriptions.  Event notifications are also
   carried in CONTROL message bodies; the <mrbnotification> element is

   defined for package event notifications.  Responses are carried
   either in REPORT message or Control Framework 200 response bodies;
   the <mrbresponse> element is defined as a package-level response.

   Note that package responses are different from framework response
   codes.  Framework error response codes (see Section 7 of [RFC6230])
   are used when the request or event notification is invalid; for
   example, a request has invalid XML (400) or is not understood (500).
   Package-level responses are carried in framework 200 response or
   REPORT message bodies.  This package's response codes are defined in
   Section 5.1.4.

5.1.1.3.  Common XML Support

   The Media Control Channel Framework [RFC6230] requires a Control
   Package definition to specify if the attributes for media dialog or
   conference references are required.

   The Publish interface defined in Section 10 does import and make use
   of the common XML schema defined in the Media Control Channel
   Framework.

   The Consumer interface defined in Section 11 does import and make use
   of the common XML schema defined in the Media Control Channel
   Framework.

5.1.1.4.  CONTROL Message Body

   A valid CONTROL message body MUST conform to the schema defined in
   Section 10 and described in Section 5.1.2.  XML messages appearing in
   CONTROL messages MUST contain either an <mrbrequest> or
   <mrbnotification> element.

5.1.1.5.  REPORT Message Body

   A valid REPORT message body MUST conform to the schema defined in
   Section 10 and described in Section 5.1.2.  XML messages appearing in
   REPORT messages MUST contain an <mrbresponse> element.

5.1.1.6.  Audit

   The 'mrb-publish/1.0' Media Control Channel Framework package does
   not require any additional auditing capability.

5.1.2.  Element Definitions

   This section defines the XML elements for the Publish interface Media
   Control Channel package defined in Section 5.1.  The formal XML
   schema definition for the Publish interface can be found in
   Section 10.

   The root element is <mrbpublish>.  All other XML elements (requests,
   responses, notifications) are contained within it.  The MRB Publish
   interface request element is detailed in Section 5.1.3.  The MRB
   Publish interface notification element is detailed in Section 5.1.5.
   The MRB Publish interface response element is detailed in
   Section 5.1.4.

   The <mrbpublish> element has the following attributes:

   version:  a token specifying the mrb-publish package version.  The
      value is fixed as '1.0' for this version of the package.  The
      attribute MUST be present.

   The <mrbpublish> element has the following child elements, and there
   MUST NOT be more than one such child element in any <mrbpublish>
   message:

      <mrbrequest> for sending an MRB request.  See Section 5.1.3.

      <mrbresponse> for sending an MRB response.  See Section 5.1.4.

      <mrbnotification> for sending an MRB notification.  See
      Section 5.1.5.

5.1.3.  <mrbrequest>

   This section defines the <mrbrequest> element used to initiate
   requests from an MRB to a Media Server.  The element describes
   information relevant for the interrogation of a Media Server.

   The <mrbrequest> element has no defined attributes.

   The <mrbrequest> element has the following child element:

      <subscription> for initiating a subscription to a Media Server
      from an MRB.  See Section 5.1.3.1.

5.1.3.1.  <subscription>

   The <subscription> element is included in a request from an MRB to a
   Media Server to provide the details relating to the configuration of
   updates (known as a subscription session).  This element can be used
   either to request a new subscription or to update an existing one
   (e.g., to change the frequency of the updates), and to remove ongoing
   subscriptions as well (e.g., to stop an indefinite update).  The MRB
   will inform the Media Server regarding how long it wishes to receive
   updates and the frequency that updates should be sent.  Updates
   related to the subscription are sent using the <mrbnotification>
   element.

   The <subscription> element has the following attributes:

   id:  Indicates a unique token representing the subscription session
      between the MRB and the Media Server.  The attribute MUST be
      present.

   seqnumber:  Indicates a sequence number to be used in conjunction
      with the subscription session ID to identify a specific
      subscription command.  The first subscription MUST contain a
      non-zero number 'seqnumber', and subsequent subscriptions MUST
      contain a higher number than the previous 'seqnumber' value.  If a
      subsequent 'seqnumber' is not higher, a 405 response code is
      generated as per Section 5.1.4.  The attribute MUST be present.

   action:  Provides the operation that should be carried out on the
      subscription:

      *  The value of 'create' instructs the Media Server to attempt to
         set up a new subscription.

      *  The value of 'update' instructs the Media Server to attempt to
         update an existing subscription.

      *  The value of 'remove' instructs the Media Server to attempt to
         remove an existing subscription and consequently stop any
         ongoing related notification.

      The attribute MUST be present.

   The <subscription> element has zero or more of the following child
   elements:

   <expires>:  Provides the amount of time in seconds that a
      subscription should be installed for notifications at the Media
      Server.  Once the amount of time has passed, the subscription
      expires, and the MRB has to subscribe again if it is still
      interested in receiving notifications from the Media Server.  The
      element MAY be present.

   <minfrequency>:  Provides the minimum frequency in seconds that the
      MRB wishes to receive notifications from the Media Server.  The
      element MAY be present.

   <maxfrequency>:  Provides the maximum frequency in seconds that the
      MRB wishes to receive notifications from the Media Server.  The
      element MAY be present.

   Please note that these three optional pieces of information provided
   by the MRB only act as a suggestion: the Media Server MAY change the
   proposed values if it considers the suggestions unacceptable (e.g.,
   if the MRB has requested a notification frequency that is too high).
   In such a case, the request would not fail, but the updated,
   acceptable values would be reported in the <mrbresponse> accordingly.

5.1.4.  <mrbresponse>

   Responses to requests are indicated by an <mrbresponse> element.

   The <mrbresponse> element has the following attributes:

   status:  numeric code indicating the response status.  The attribute
      MUST be present.

   reason:  string specifying a reason for the response status.  The
      attribute MAY be present.

   The <mrbresponse> element has a single child element:

      <subscription> for providing details related to a subscription
      requested by a Media Server (see below in this section).

   The following status codes are defined for 'status':

   +-----------+-------------------------------------------------------+
   | code      | description                                           |
   +-----------+-------------------------------------------------------+
   | 200       | OK                                                    |
   |           |                                                       |
   | 400       | Syntax error                                          |
   |           |                                                       |
   | 401       | Unable to create Subscription                         |
   |           |                                                       |
   | 402       | Unable to update Subscription                         |
   |           |                                                       |
   | 403       | Unable to remove Subscription                         |
   |           |                                                       |
   | 404       | Subscription does not exist                           |
   |           |                                                       |
   | 405       | Wrong sequence number                                 |
   |           |                                                       |
   | 406       | Subscription already exists                           |
   |           |                                                       |
   | 420       | Unsupported attribute or element                      |
   +-----------+-------------------------------------------------------+

                    Table 1: <mrbresponse> Status Codes

   If a new subscription request made by an MRB (action='create') has
   been accepted, the Media Server MUST reply with an <mrbresponse> with
   status code 200.  The same rule applies whenever a request to update
   (action='update') or remove (action='remove') an existing transaction
   can be fulfilled by the Media Server.

   A subscription request, nevertheless, may fail for several reasons.
   In such a case, the status codes defined in Table 1 must be used
   instead.  Specifically, if the Media Server fails to handle a request
   due to a syntax error in the request itself (e.g., incorrect XML,
   violation of the schema constraints, or invalid values in any of the
   attributes/elements), the Media Server MUST reply with an
   <mrbresponse> with status code 400.  If a syntactically correct
   request fails because the request also includes any attribute/element
   the Media Server doesn't understand, the Media Server MUST reply with
   an <mrbresponse> with status code 420.  If a syntactically correct
   request fails because the MRB wants to create a new subscription, but
   the provided unique 'id' for the subscription already exists, the
   Media Server MUST reply with an <mrbresponse> with status code 406.
   If a syntactically correct request fails because the MRB wants to
   update/remove a subscription that doesn't exist, the Media Server
   MUST reply with an <mrbresponse> with status code 404.  If the Media

   Server is unable to accept a request for any other reason (e.g., the
   MRB has no more resources to fulfill the request), the Media Server
   MUST reply with an <mrbresponse> with status code 401/402/403,
   depending on the action the MRB provided in its request:

   o  action='create' --> 401;

   o  action='update' --> 402;

   o  action='remove' --> 403;

   A response to a subscription request that has a status code of 200
   indicates that the request is successful.  The response MAY also
   contain a <subscription> child that describes the subscription.  The
   <subscription> child MAY contain 'expires', 'minfrequency', and
   'maxfrequency' values even if they were not contained in the request.

   The Media Server can choose to change the suggested 'expires',
   'minfrequency', and 'maxfrequency' values provided by the MRB in its
   <mrbrequest> if it considers them unacceptable (e.g., the requested
   frequency range is too high).  In such a case, the response MUST
   contain a <subscription> element describing the subscription as the
   Media Server accepted it, and the Media Server MUST include in the
   <subscription> element all of those values that it modified relative
   to the request, to inform the MRB about the change.

5.1.5.  <mrbnotification>

   The <mrbnotification> element is included in a request from a Media
   Server to an MRB to provide the details relating to current status.
   The Media Server will inform the MRB of its current status as defined
   by the information in the <subscription> element.  Updates are sent
   using the <mrbnotification> element.

   The <mrbnotification> element has the following attributes:

   id:  indicates a unique token representing the session between the
      MRB and the Media Server and is the same as the one appearing in
      the <subscription> element.  The attribute MUST be present.

   seqnumber:  indicates a sequence number to be used in conjunction
      with the subscription session ID to identify a specific
      notification update.  The first notification update MUST contain a
      non-zero number 'seqnumber', and subsequent notification updates
      MUST contain a higher number than the previous 'seqnumber' value.
      If a subsequent 'seqnumber' is not higher, the situation should be

      considered an error by the entity receiving the notification
      update.  How the receiving entity deals with this situation is
      implementation specific.  The attribute MUST be present.

   It's important to point out that the 'seqnumber' that appears in an
   <mrbnotification> is not related to the 'seqnumber' appearing in a
   <subscription>.  In fact, the latter is associated with subscriptions
   and would increase at every command issued by the MRB, while the
   former is associated with the asynchronous notifications the Media
   Server would trigger according to the subscription and as such would
   increase at every notification message to enable the MRB to keep
   track of them.

   The following sub-sections provide details of the child elements that
   make up the contents of the <mrbnotification> element.

5.1.5.1.  <media-server-id>

   The <media-server-id> element provides a unique system-wide
   identifier for a Media Server instance.  The element MUST be present
   and MUST be chosen such that it is extremely unlikely that two
   different Media Servers would present the same id to a given MRB.

5.1.5.2.  <supported-packages>

   The <supported-packages> element provides the list of Media Control
   Channel packages supported by the Media Server.  The element MAY be
   present.

   The <supported-packages> element has no attributes.

   The <supported-packages> element has a single child element:

   <package>:  Gives the name of a package supported by the Media
      Server.  The <package> element has a single attribute, 'name',
      which provides the name of the supported Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230].

5.1.5.3.  <active-rtp-sessions>

   The <active-rtp-sessions> element provides information detailing the
   current active Real-time Transport Protocol (RTP) sessions.  The
   element MAY be present.

   The <active-rtp-sessions> element has no attributes.

   The <active-rtp-sessions> element has a single child element:

   <rtp-codec>:  Describes a supported codec and the number of active
      sessions using that codec.  The <rtp-codec> element has one
      attribute.  The value of the attribute, 'name', is a media type
      (which can include parameters per [RFC6381]).  The <rtp-codec>
      element has two child elements.  The child element <decoding> has
      as content the decimal number of RTP sessions being decoded using
      the specified codec, and the child element <encoding> has as
      content the decimal number of RTP sessions being encoded using the
      specified codec.

5.1.5.4.  <active-mixer-sessions>

   The <active-mixer-sessions> element provides information detailing
   the current active mixed RTP sessions.  The element MAY be present.

   The <active-mixer-sessions> element has no attributes.

   The <active-mixer-sessions> element has a single child element:

   <active-mix>:  Describes a mixed active RTP session.  The
      <active-mix> element has one attribute.  The value of the
      attribute, 'conferenceid', is the name of the mix.  The
      <active-mix> element has one child element.  The child element,
      <rtp-codec>, contains the same information relating to RTP
      sessions as that defined in Section 5.1.5.3.  The element MAY be
      present.

5.1.5.5.  <non-active-rtp-sessions>

   The <non-active-rtp-sessions> element provides information detailing
   the currently available inactive RTP sessions, that is, how many more
   RTP streams this Media Server can support.  The element MAY be
   present.

   The <non-active-rtp-sessions> element has no attributes.

   The <non-active-rtp-sessions> element has a single child element:

   <rtp-codec>:  Describes a supported codec and the number of
      non-active sessions for that codec.  The <rtp-codec> element has
      one attribute.  The value of the attribute, 'name', is a media
      type (which can include parameters per [RFC6381]).  The
      <rtp-codec> element has two child elements.  The child element
      <decoding> has as content the decimal number of RTP sessions

      available for decoding using the specified codec, and the child
      element <encoding> has as content the decimal number of RTP
      sessions available for encoding using the specified codec.

5.1.5.6.  <non-active-mixer-sessions>

   The <non-active-mixer-sessions> element provides information
   detailing the current inactive mixed RTP sessions, that is, how many
   more mixing sessions this Media Server can support.  The element MAY
   be present.

   The <non-active-mixer-sessions> element has no attributes.

   The <non-active-mixer-sessions> element has a single child element:

   <non-active-mix>:  Describes available mixed RTP sessions.  The
      <non-active-mix> element has one attribute.  The value of the
      attribute, 'available', is the number of mixes that could be used
      using that profile.  The <non-active-mix> element has one child
      element.  The child element, <rtp-codec>, contains the same
      information relating to RTP sessions as that defined in
      Section 5.1.5.5.  The element MAY be present.

5.1.5.7.  <media-server-status>

   The <media-server-status> element provides information detailing the
   current status of the Media Server.  The element MUST be present.  It
   can return one of the following values:

   active:  Indicates that the Media Server is available for service.

   deactivated:  Indicates that the Media Server has been withdrawn from
      service, and as such requests should not be sent to it before it
      becomes 'active' again.

   unavailable:  Indicates that the Media Server continues to process
      past requests but cannot accept new requests, and as such should
      not be contacted before it becomes 'active' again.

   The <media-server-status> element has no attributes.

   The <media-server-status> element has no child elements.

5.1.5.8.  <supported-codecs>

   The <supported-codecs> element provides information detailing the
   current codecs supported by a Media Server and associated actions.
   The element MAY be present.

   The <supported-codecs> element has no attributes.

   The <supported-codecs> element has a single child element:

   <supported-codec>:  Has a single attribute, 'name', which provides
      the name of the codec about which this element provides
      information.  A valid value is a media type that, depending on its
      definition, can include additional parameters (e.g., [RFC6381]).
      The <supported-codec> element then has a further child element,
      <supported-codec-package>.  The <supported-codec-package> element
      has a single attribute, 'name', which provides the name of the
      Media Control Channel Framework package, compliant with
      Section 13.1.1 of [RFC6230], for which the codec support applies.
      The <supported-codec-package> element has zero or more
      <supported-action> children, each one of which describes an action
      that a Media Server can apply to this codec:

      *  'decoding', meaning a decoder for this codec is available;

      *  'encoding', meaning an encoder for this codec is available;

      *  'passthrough', meaning the Media Server is able to pass a
         stream encoded using that codec through, without re-encoding.

5.1.5.9.  <application-data>

   The <application-data> element provides an arbitrary string of
   characters as application-level data.  This data is meant to only
   have meaning at the application-level logic and as such is not
   otherwise restricted by this specification.  The set of allowed
   characters is the same as those in XML (viz., tab, carriage return,
   line feed, and the legal characters of Unicode and ISO/IEC 10646
   [ISO.10646.2012] (see also Section 2.2 of
   <http://www.w3.org/TR/xml/>)).  The element MAY be present.

   The <application-data> element has no attributes.

   The <application-data> element has no child elements.

5.1.5.10.  <file-formats>

   The <file-formats> element provides a list of file formats supported
   for the purpose of playing media.  The element MAY be present.

   The <file-formats> element has no attributes.

   The <file-formats> element has zero of more the following child
   elements:

   <supported-format>:  Has a single attribute, 'name', which provides
      the type of file format that is supported.  A valid value is a
      media type that, depending on its definition, can include
      additional parameters (e.g., [RFC6381]).  The <supported-format>
      element then has a further child element,
      <supported-file-package>.  The <supported-file-package> element
      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the file
      format support applies.

5.1.5.11.  <max-prepared-duration>

   The <max-prepared-duration> element provides the maximum amount of
   time a media dialog will be kept in the prepared state before timing
   out (see Section 4.4.2.2.6 of RFC 6231 [RFC6231].  The element MAY be
   present.

   The <max-prepared-duration> element has no attributes.

   The <max-prepared-duration> element has a single child element:

   <max-time>:  Has a single attribute, 'max-time-seconds', which
      provides the amount of time in seconds that a media dialog can be
      in the prepared state.  The <max-time> element then has a further
      child element, <max-time-package>.  The <max-time-package> element
      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the time
      period applies.

5.1.5.12.  <dtmf-support>

   The <dtmf-support> element specifies the supported methods to detect
   Dual-Tone Multi-Frequency (DTMF) tones and to generate them.  The
   element MAY be present.

   The <dtmf-support> element has no attributes.

   The <dtmf-support> element has zero of more of the following child
   elements:

   <detect>:  Indicates the support for DTMF detection.  The <detect>
      element has no attributes.  The <detect> element then has a
      further child element, <dtmf-type>.  The <dtmf-type> element has
      two attributes: 'name' and 'package'.  The 'name' attribute
      provides the type of DTMF being used, and it can only be a case-
      insensitive string containing either 'RFC4733' [RFC4733] or
      'Media' (detecting tones as signals from the audio stream).  The
      'package' attribute provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], for
      which the DTMF type applies.

   <generate>:  Indicates the support for DTMF generation.  The
      <generate> element has no attributes.  The <generate> element then
      has a further child element, <dtmf-type>.  The <dtmf-type> element
      has two attributes: 'name' and 'package'.  The 'name' attribute
      provides the type of DTMF being used, and it can only be a case-
      insensitive string containing either 'RFC4733' [RFC4733] or
      'Media' (generating tones as signals in the audio stream).  The
      'package' attribute provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], for
      which the DTMF type applies.

   <passthrough>:  Indicates the support for passing DTMF through
      without re-encoding.  The <passthrough> element has no attributes.
      The <passthrough> element then has a further child element,
      <dtmf-type>.  The <dtmf-type> element has two attributes: 'name'
      and 'package'.  The 'name' attribute provides the type of DTMF
      being used, and it can only be a case-insensitive string
      containing either 'RFC4733' [RFC4733] or 'Media' (passing tones as
      signals through the audio stream).  The 'package' attribute
      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the DTMF
      type applies.

5.1.5.13.  <mixing-modes>

   The <mixing-modes> element provides information about the support for
   audio and video mixing of a Media Server, specifically a list of
   supported algorithms to mix audio and a list of supported video
   presentation layouts.  The element MAY be present.

   The <mixing-modes> element has no attributes.

   The <mixing-modes> element has zero or more of the following child
   elements:

   <audio-mixing-modes>:  Describes the available algorithms for audio
      mixing.  The <audio-mixing-modes> element has no attributes.  The
      <audio-mixing-modes> element has one child element.  The child
      element, <audio-mixing-mode>, contains a specific available
      algorithm.  Valid values for the <audio-mixing-mode> element are
      algorithm names, e.g., 'nbest' and 'controller' as defined in
      [RFC6505].  The element has a single attribute, 'package'.  The
      attribute 'package' provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], for
      which the algorithm support applies.

   <video-mixing-modes>:  Describes the available video presentation
      layouts and the supported functionality related to video mixing.
      The <video-mixing-modes> element has two attributes: 'vas' and
      'activespeakermix'.  The 'vas' attribute is of type boolean with a
      value of 'true' indicating that the Media Server supports
      automatic Voice Activated Switching.  The 'activespeakermix' is of
      type boolean with a value of 'true' indicating that the Media
      Server is able to prepare an additional video stream for the
      loudest speaker participant without its contribution.  The
      <video-mixing-modes> element has one child element.  The child
      element, <video-mixing-mode>, contains the name of a specific
      video presentation layout.  The name may refer to one of the
      predefined video layouts defined in the XCON conference
      information data model [RFC6501], or to non-XCON layouts as well,
      as long as they are properly prefixed according to the schema they
      belong to.  The <video-mixing-mode> element has a single
      attribute, 'package'.  The attribute 'package' provides the name
      of the Media Control Channel Framework package, compliant with
      Section 13.1.1 of [RFC6230], for which the algorithm support
      applies.

5.1.5.14.  <supported-tones>

   The <supported-tones> element provides information about which tones
   a Media Server is able to play and recognize.  In particular, the
   support is reported by referring to both support for country codes
   (ISO 3166-1 [ISO.3166-1]) and supported functionality (ITU-T
   Recommendation Q.1950 [ITU-T.Q.1950]).  The element MAY be present.

   The <supported-tones> element has no attributes.

   The <supported-tones> element has zero or more of the following child
   elements:

   <supported-country-codes>:  Describes the supported country codes
      with respect to tones.  The <supported-country-codes> element has
      no attributes.  The <supported-country-codes> element has one
      child element.  The child element, <country-code>, reports support
      for a specific country code, compliant with the ISO 3166-1
      [ISO.3166-1] specification.  The <country-code> element has a
      single attribute, 'package'.  The attribute 'package' provides the
      name of the Media Control Channel Framework package, compliant
      with Section 13.1.1 of [RFC6230], in which the tones from the
      specified country code are supported.

   <supported-h248-codes>:  Describes the supported H.248 codes with
      respect to tones.  The <supported-h248-codes> element has no
      attributes.  The <supported-h248-codes> element has one child
      element.  The child element, <h248-code>, reports support for a
      specific H.248 code, compliant with the ITU-T Recommendation
      Q.1950 [ITU-T.Q.1950] specification.  The codes can be either
      specific (e.g., cg/dt to only report the Dial Tone from the Call
      Progress Tones package) or generic (e.g., cg/* to report all the
      tones from the Call Progress Tones package), using wildcards.  The
      <h248-code> element has a single attribute, 'package'.  The
      attribute 'package' provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], in
      which the specified codes are supported.

5.1.5.15.  <file-transfer-modes>

   The <file-transfer-modes> element allows the Media Server to specify
   which scheme names are supported for transferring files to a Media
   Server for each Media Control Channel Framework package type, for
   example, whether the Media Server supports fetching resources via
   HTTP, HTTPS, NFS, etc.  The element MAY be present.

   The <file-transfer-modes> element has no attributes.

   The <file-transfer-modes> element has a single child element:

   <file-transfer-mode>:  Has two attributes: 'name' and 'package'.  The
      'name' attribute provides the scheme name of the protocol that can
      be used for file transfer (e.g., HTTP, HTTPS, NFS, etc.); the
      value of the attribute is case insensitive.  The 'package'
      attribute provides the name of the Media Control Channel Framework
      package, compliant with the specification in the related IANA
      registry (e.g., "msc-ivr/1.0"), for which the scheme name applies.

   It is important to point out that this element provides no
   information about whether or not the Media Server supports any flavor
   of live streaming: for instance, a value of "HTTP" for the IVR
   (Interactive Voice Response) Package would only mean the 'http'
   scheme makes sense to the Media Server within the context of that
   package.  Whether or not the Media Server can make use of HTTP to
   only fetch resources, or also to attach an HTTP live stream to a
   call, is to be considered implementation specific to the Media Server
   and irrelevant to the Application Server and/or MRB.  Besides, the
   Media Server supporting a scheme does not imply that it also supports
   the related secure versions: for instance, if the Media Server
   supports both HTTP and HTTPS, both the schemes will appear in the
   element.  A lack of the "HTTPS" value would need to be interpreted as
   a lack of support for the 'https' scheme.

5.1.5.16.  <asr-tts-support>

   The <asr-tts-support> element provides information about the support
   for Automatic Speech Recognition (ASR) and Text-to-Speech (TTS)
   functionality in a Media Server.  The functionality is reported by
   referring to the supported languages (using ISO 639-1 [ISO.639.2002]
   codes) regarding both ASR and TTS.  The element MAY be present.

   The <asr-tts-support> element has no attributes.

   The <asr-tts-support> element has zero or more of the following child
   elements:

   <asr-support>:  Describes the available languages for ASR.  The
      <asr-support> element has no attributes.  The <asr-support>
      element has one child element.  The child element, <language>,
      reports that the Media Server supports ASR for a specific
      language.  The <language> element has a single attribute,
      'xml:lang'.  The attribute 'xml:lang' contains the ISO 639-1
      [ISO.639.2002] code of the supported language.

   <tts-support>:  Describes the available languages for TTS.  The
      <tts-support> element has no attributes.  The <tts-support>
      element has one child element.  The child element, <language>,
      reports that the Media Server supports TTS for a specific
      language.  The <language> element has a single attribute,
      'xml:lang'.  The attribute 'xml:lang' contains the ISO 639-1
      [ISO.639.2002] code of the supported language.

5.1.5.17.  <vxml-support>

   The <vxml-support> element specifies if the Media Server supports
   VoiceXML (VXML) and, if it does, through which protocols the support
   is exposed (e.g., via the control framework, RFC 4240 [RFC4240], or
   RFC 5552 [RFC5552]).  The element MAY be present.

   The <vxml-support> element has no attributes.

   The <vxml-support> element has a single child element:

   <vxml-mode>:  Has two attributes: 'package' and 'support'.  The
      'package' attribute provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], for
      which the VXML support applies.  The 'support' attribute provides
      the type of VXML support provided by the Media Server (e.g.,
      RFC 5552 [RFC5552], RFC 4240 [RFC4240], or the IVR Package
      [RFC6231]), and valid values are case-insensitive RFC references
      (e.g., "rfc6231" to specify that the Media Server supports
      VoiceXML as provided by the IVR Package [RFC6231]).

   The presence of at least one <vxml-mode> child element would indicate
   that the Media Server does support VXML as specified by the child
   element itself.  An empty <vxml> element would otherwise indicate
   that the Media Server does not support VXML at all.

5.1.5.18.  <media-server-location>

   The <media-server-location> element provides information about the
   civic location of a Media Server.  Its description makes use of the
   Civic Address Schema standardized in RFC 5139 [RFC5139].  The element
   MAY be present.  More precisely, this section is entirely optional,
   and it's implementation specific to fill it with just the details
   each implementer deems necessary for any optimization that may be
   needed.

   The <media-server-location> element has no attributes.

   The <media-server-location> element has a single child element:

   <civicAddress>:  Describes the civic address location of the Media
      Server, whose representation refers to Section 4 of RFC 5139
      [RFC5139].

5.1.5.19.  <label>

   The <label> element allows a Media Server to declare a piece of
   information that will be understood by the MRB.  For example, the
   Media Server can declare if it's a blue or green one.  It's a string
   to allow arbitrary values to be returned to allow arbitrary
   classification.  The element MAY be present.

   The <label> element has no attributes.

   The <label> element has no child elements.

5.1.5.20.  <media-server-address>

   The <media-server-address> element allows a Media Server to provide a
   direct SIP URI where it can be reached (e.g., the URI that the
   Application Server would call in order to set up a Control Channel
   and relay SIP media dialogs).  The element MAY be present.

   The <media-server-address> element has no attributes.

   The <media-server-address> element has no child elements.

5.1.5.21.  <encryption>

   The <encryption> element allows a Media Server to declare support for
   encrypting RTP media streams using RFC 3711 [RFC3711].  The element
   MAY be present.  If the element is present, then the Media Server
   supports DTLS-SRTP (a Secure Real-time Transport Protocol (SRTP)
   extension for Datagram Transport Layer Security (DTLS)) [RFC5763].

   The <encryption> element has no attributes.

   The <encryption> element has no child elements.

5.2.  Media Service Resource Consumer Interface

   The Media Server Consumer interface provides the ability for clients
   of an MRB, such as Application Servers, to request an appropriate
   Media Server to satisfy specific criteria.  This interface allows a
   client to pass detailed meta-information to the MRB to help select an
   appropriate Media Server.  The MRB is then able to make an informed

   decision and provide the client with an appropriate Media Server
   resource.  The MRB Consumer interface includes both 1) the In-line
   Aware MRB Mode (IAMM), which uses the Session Initiation Protocol
   (SIP) and 2) the Query mode, which uses the Hypertext Transfer
   Protocol (HTTP) [RFC2616].  The MRB Consumer interface does not
   include the In-line Unaware Mode (IUMM), which is further explained
   in Section 5.3.  The following sub-sections provide guidance on
   using the Consumer interface, which is represented by the
   'application/mrb-consumer+xml' media type in Section 11, with HTTP
   and SIP.

5.2.1.  Query Mode/HTTP Consumer Interface Usage

   An appropriate interface for such a 'query' style interface is in
   fact an HTTP usage.  Using HTTP and XML combined reduces complexity
   and encourages the use of common tools that are widely available in
   the industry today.  The following information explains the primary
   operations required to request and then receive information from an
   MRB, by making use of HTTP [RFC2616] and HTTPS [RFC2818] as transport
   for a query for a media resource, and the appropriate response.

   The media resource query, as defined by the <mediaResourceRequest>
   element from Section 11, MUST be carried in the body of an HTTP/HTTPS
   POST request.  The media type contained in the HTTP/HTTPS request/
   response MUST be 'application/mrb-consumer+xml'.  This value MUST be
   reflected in the appropriate HTTP headers, such as 'Content-Type' and
   'Accept'.  The body of the HTTP/HTTPS POST request MUST only contain
   an <mrbconsumer> root element with only one child
   <mediaResourceRequest> element as defined in Section 11.

   The media resource response to a query, as defined by the
   <mediaResourceResponse> element from Section 11, MUST be carried in
   the body of an HTTP/HTTPS 200 response to the original HTTP/HTTPS
   POST request.  The media type contained in the HTTP/HTTPS request/
   response MUST be 'application/mrb-consumer+xml'.  This value MUST be
   reflected in the appropriate HTTP headers, such as 'Content-Type' and
   'Accept'.  The body of the HTTP/HTTPS 200 response MUST only contain
   an <mrbconsumer> root element with only one child
   <mediaResourceResponse> element as defined in Section 11.

   When an Application Server wants to release previously awarded media
   resources granted through a prior request/response exchange with an
   MRB, it will send a new request with an <action> element with value
   'remove', as described in Section 5.2.3 ("Consumer Interface Lease
   Mechanism").

5.2.2.  In-Line Aware Mode/SIP Consumer Interface Usage

   This document provides a complete toolkit for MRB deployment that
   includes the ability to interact with an MRB using SIP for the
   Consumer interface.  The following information explains the primary
   operations required to request and then receive information from an
   MRB, by making use of SIP [RFC3261] as transport for a request for
   media resources, and the appropriate response when using IAMM as the
   mode of operation (as discussed in Section 5.2.2.1).

   The use of IAMM, besides having the MRB select appropriate media
   resources on behalf of a client application, includes setting up
   either a Control Framework Control Channel between an Application
   Server and one of the Media Servers (Section 5.2.2.1) or a media
   dialog session between an Application Server and one of the Media
   Servers (Section 5.2.2.2).  Note that in either case the SIP URIs of
   the selected Media Servers are made known to the requesting
   Application Server in the SIP 200 OK response by means of one or more
   <media-server-address> child elements in the <response-session-info>
   element (Section 5.2.6).

5.2.2.1.  IAMM and Setting Up a Control Framework Control Channel

   The media resource request information, as defined by the
   <mediaResourceRequest> element from Section 11, is carried in a SIP
   INVITE request.  The INVITE request will be constructed as it would
   have been to connect to a Media Server, as defined by the Media
   Control Channel Framework [RFC6230].  It should be noted that this
   specification does not exclude the use of an offerless INVITE as
   defined in RFC 3261 [RFC3261].  Using offerless INVITE messages to an
   MRB can potentially cause confusion when applying resource selection
   algorithms, and an MRB, like any other SIP device, can choose to
   reject with a 4xx response.  For an offerless INVITE to be treated
   appropriately, additional contextual information would need to be
   provided with the request; this is out of scope for this document.
   The following additional steps MUST be followed when using the
   Consumer interface:

   o  The Consumer client will include a payload in the SIP INVITE
      request of type 'multipart/mixed' [RFC2046].  One of the parts to
      be included in the 'multipart/mixed' payload MUST be the
      'application/sdp' format, which is constructed as specified in the
      Media Control Channel Framework [RFC6230].

   o  Another part of the 'multipart/mixed' payload MUST be of type
      'application/mrb-consumer+xml', as specified in this document and
      defined in Section 11.  The body part MUST be an XML document
      without prolog and whose root element is <mediaResourceRequest>.

   o  The INVITE request will then be dispatched to the MRB, as defined
      by [RFC6230].

   On receiving a SIP INVITE request containing the multipart/mixed
   payload as specified previously, the MRB will complete a number of
   steps to fulfill the request.  It will:

   o  Extract the multipart MIME payload from the SIP INVITE request.
      It will then use the contextual information provided by the client
      in the 'application/mrb-consumer+xml' part to determine which
      Media Server (or Media Servers, if more than one is deemed to be
      needed) should be selected to service the request.

   o  Extract the 'application/sdp' part from the payload and use it as
      the body of a new SIP INVITE request for connecting the client to
      one of the selected Media Servers, as defined in the Media Channel
      Control Framework [RFC6230].  The policy the MRB follows to pick a
      specific Media Server out of the Media Servers it selects is
      implementation specific and out of scope for this document.  It is
      important to configure the SIP elements between the MRB and the
      Media Server in such a way that the INVITE will not fork.  In the
      case of a failure in reaching the chosen Media Server, the MRB
      SHOULD proceed to the next one, if available.

   If none of the available Media Servers can be reached, the MRB MUST
   reply with a SIP 503 error message that includes a Retry-After header
   with a non-zero value.  The Application Server MUST NOT attempt to
   set up a new session before the time that the MRB asked it to wait
   has passed.

   If at least one Media Server is reachable, the MRB acts as a Back-to-
   Back User Agent (B2BUA) that extracts the 'application/
   mrb-consumer+xml' information from the SIP INVITE request and then
   sends a corresponding SIP INVITE request to the Media Server it has
   selected, to negotiate a Control Channel as defined in the Media
   Channel Control Framework [RFC6230].

   In the case of a failure in negotiating the Control Channel with the
   Media Server, the MRB SHOULD proceed to the next one, if available,
   as explained above.  If none of the available Media Servers can be
   reached, or the negotiations of the Control Channel with all of them
   fail, the MRB MUST reply with a SIP 503 error message that includes a
   Retry-After header with a non-zero value.  The Application Server
   MUST NOT attempt to set up a new session before the time that the MRB
   asked it to wait has expired.

   Once the MRB receives the SIP response from the selected media
   resource (i.e., Media Server), it will in turn respond to the
   requesting client (i.e., Application Server).

   The media resource response generated by an MRB to a request, as
   defined by the <mediaResourceResponse> element from Section 11, MUST
   be carried in the payload of a SIP 200 OK response to the original
   SIP INVITE request.  The SIP 200 OK response will be constructed as
   it would have been to connect from a Media Server, as defined by the
   Media Control Channel Framework [RFC6230].  The following additional
   steps MUST be followed when using the Consumer interface:

   o  Include a payload in the SIP 200 response of type 'multipart/
      mixed' as per RFC 2046 [RFC2046].  One of the parts to be included
      in the 'multipart/mixed' payload MUST be the 'application/sdp'
      format, which is constructed as specified in the Media Control
      Channel Framework [RFC6230] and based on the incoming response
      from the selected media resource.

   o  Another part of the 'multipart/mixed' payload MUST be of type
      'application/mrb-consumer+xml', as specified in this document and
      defined in Section 11.  Only the <mediaResourceResponse> and its
      child elements can be included in the payload.

   o  The SIP 200 response will then be dispatched from the MRB.

   o  A SIP ACK to the 200 response will then be sent back to the MRB.

   Considering that the use of SIP as a transport for Consumer
   transactions may result in failure, the IAMM relies on a successful
   INVITE transaction to address the previously discussed sequence
   (using the 'seq' XML element) increment mechanism.  This means that
   if the INVITE is unsuccessful for any reason, the Application Server
   MUST use the same 'seq' value as previously used for the next
   Consumer request that it may want to send to the MRB for the same
   session.

   An MRB implementation may be programmed to conclude that the
   requested resources are no longer needed when it receives a SIP BYE
   from the Application Server or Media Server that concludes the SIP
   dialog that initiated the request, or when the lease (Section 5.2.3)
   interval expires.

5.2.2.2.  IAMM and Setting Up a Media Dialog

   This scenario is identical to the description in the previous section
   for setting up a Control Framework Control Channel, with the
   exception that the application/sdp payload conveys content
   appropriate for setting up the media dialog to the media resource, as
   per RFC 3261 [RFC3261], instead of setting up a Control Channel.

5.2.3.  Consumer Interface Lease Mechanism

   The Consumer interface defined in Sections 5.2 and 11 allows a client
   to request an appropriate media resource based on information
   included in the request (either an HTTP POST or SIP INVITE message).
   In the case of success, the response that is returned to the client
   MUST contain a <response-session-info> element in either the SIP 200
   or HTTP 200 response.  The success response contains the description
   of certain resources that have been reserved to a specific Consumer
   client in a (new or revised) "resource session", which is identified
   in the <response-session-info>.  The resource session is a "lease",
   in that the reservation is scheduled to expire at a particular time
   in the future, releasing the resources to be assigned for other uses.
   The lease may be extended or terminated earlier by future Consumer
   client requests that identify and reference a specific resource
   session.

   Before delving into the details of such a lease mechanism, it is
   worth clarifying its role within the context of the Consumer
   interface.  As explained in Section 5.1, the knowledge the MRB has of
   the resources of all the Media Servers it is provisioned to manage is
   not real-time.  How an MRB actually manages such resources is
   implementation specific -- for example, an implementation may choose
   to have the MRB keeping track and state of the allocated resources,
   or simply rely on the Media Servers themselves to provide the
   information using the Publish interface.  Further information may
   also be inferred by the signaling, in the case where an MRB is in the
   path of media dialogs.

   The <mediaResourceResponse> element returned from the MRB contains a
   <response-session-info> element if the request is successful.  The
   <response-session-info> element has zero or more of the following
   child elements, which provide the appropriate resource session
   information:

   o  <session-id> is a unique identifier that enables a Consumer client
      and MRB to correlate future media resource requests related to an
      initial media resource request.  The <session-id> MUST be included
      in all future related requests (see the <session-id> paragraph
      later in this section, where constructing a subsequent request is
      discussed).

   o  <seq> is a numeric value returned to the Consumer client.  On
      issuing any future requests related to the media resource session
      (as determined by the <session-id> element), the Consumer client
      MUST increment the value returned in the <seq> element and include
      it in the request (see the <seq> paragraph later in this section,
      where constructing a subsequent request is discussed).  Its value
      is a non-negative integer that MUST be limited within the
      0..2^31-1 range.

   o  <expires> provides a value indicating the number of seconds that
      the request for media resources is deemed alive.  The Consumer
      client should issue a refresh of the request, as discussed later
      in this section, if the expiry is due to fire and the media
      resources are still required.

   o  <media-server-address> provides information representing an
      assigned Media Server.  More instances of this element may appear
      should the MRB assign more Media Servers to a Consumer request.

   The <mediaResourceRequest> element is used in subsequent Consumer
   interface requests if the client wishes to manipulate the session.
   The Consumer client MUST include the <session-info> element, which
   enables the receiving MRB to determine an existing media resource
   allocation session.  The <session-info> element has the following
   child elements, which provide the appropriate resource session
   information to the MRB:

   o  <session-id> is a unique identifier that allows a Consumer client
      to indicate the appropriate existing media resource session to be
      manipulated by the MRB for this request.  The value was provided
      by the MRB in the initial request for media resources, as
      discussed earlier in this section (<session-id> element included
      as part of the <session-info> element in the initial
      <mediaResourceResponse>).

   o  <seq> is a numeric value returned to the Consumer client in the
      initial request for media resources, as discussed earlier in this
      section (<seq> element included as part of the <session-info>
      element in the initial <mediaResourceResponse>).  On issuing any
      future requests related to the specific media resource session (as
      determined by the <session-id> element), the Consumer client MUST
      increment the value returned in the <seq> element from the initial
      response (contained in the <mediaResourceResponse>) for every new
      request.  The value of the <seq> element in requests acts as a
      counter and when used in conjunction with the unique <session-id>
      allows for unique identification of a request.  As anticipated
      before, the <seq> value is limited to the 0..2^31-1 range: in the
      unlikely case that the counter increases to reach the highest
      allowed value, the <seq> value MUST be set to 0.  The first
      numeric value for the <seq> element is not meant to be '1' but
      SHOULD be generated randomly by the MRB: this is to reduce the
      chances of a malicious MRB disrupting the session created by this
      MRB, as explained in Section 12.

   o  <action> provides the operation to be carried out by the MRB on
      receiving the request:

      *  The value of 'update' is a request by the Consumer client to
         update the existing session on the MRB with alternate media
         resource requirements.  If the requested resource information
         is identical to the existing MRB session, the MRB will attempt
         a session refresh.  If the information has changed, the MRB
         will attempt to update the existing session with the new
         information.  If the operation is successful, the 200 status
         code in the response is returned in the status attribute of the
         <mediaResourceResponseType> element.  If the operation is not
         successful, a 409 status code in the response is returned in
         the status attribute of the <mediaResourceResponseType>
         element.

      *  The value of 'remove' is a request by the Consumer client to
         remove the session on the MRB.  This provides a mechanism for
         Consumer clients to release unwanted resources before they
         expire.  If the operation is successful, a 200 status code in
         the response is returned in the status attribute of the
         <mediaResourceResponseType> element.  If the operation is not
         successful, a 410 status code in the response is returned in
         the status attribute of the <mediaResourceResponseType>
         element.

   Omitting the 'action' attribute means requesting a new set of
   resources.

   When used with HTTP, the <session-info> element MUST be included in
   an HTTP POST message (as defined in [RFC2616]).  When used with SIP,
   the <session-info> element MUST instead be included in either a SIP
   INVITE or a SIP re-INVITE (as defined in [RFC3261]), or in a SIP
   UPDATE (as defined in [RFC3311]) request: in fact, any SIP dialog, be
   it a new or an existing one, can be exploited to carry leasing
   information, and as such new SIP INVITE messages can update other
   leases as well as request a new one.

   With IAMM, the Application Server or Media Server will eventually
   send a SIP BYE to end the SIP session, whether it was for a Control
   Channel or a media dialog.  That BYE contains no Consumer interface
   lease information.

5.2.4.  <mrbconsumer>

   This section defines the XML elements for the Consumer interface.
   The formal XML schema definition for the Consumer interface can be
   found in Section 11.

   The root element is <mrbconsumer>.  All other XML elements (requests,
   responses) are contained within it.  The MRB Consumer interface
   request element is detailed in Section 5.2.5.1.  The MRB Consumer
   interface response element is detailed in Section 5.2.6.1.

   The <mrbconsumer> element has the following attributes:

   version:  a token specifying the mrb-consumer package version.  The
      value is fixed as '1.0' for this version of the package.  The
      attribute MUST be present.

   The <mrbconsumer> element may have zero or more children of one of
   the following child element types:

      <mediaResourceRequest> for sending a Consumer request.  See
      Section 5.2.5.1.

      <mediaResourceResponse> for sending a Consumer response.  See
      Section 5.2.6.1.

5.2.5.  Media Service Resource Request

   This section provides the element definitions for use in Consumer
   interface requests.  The requests are carried in the
   <mediaResourceRequest> element.

5.2.5.1.  <mediaResourceRequest>

   The <mediaResourceRequest> element provides information for clients
   wishing to query an external MRB entity.  The <mediaResourceRequest>
   element has a single mandatory attribute, 'id': this attribute
   contains a random identifier, generated by the client, that will be
   included in the response in order to map it to a specific request.
   The <mediaResourceRequest> element has <generalInfo>, <ivrInfo>, and
   <mixerInfo> as child elements.  These three elements are used to
   describe the requirements of a client requesting a Media Server and
   are covered in Sections 5.2.5.1.1, 5.2.5.1.2, and 5.2.5.1.3,
   respectively.

5.2.5.1.1.  <generalInfo>

   The <generalInfo> element provides general Consumer request
   information that is neither IVR specific nor mixer specific.  This
   includes session information that can be used for subsequent requests
   as part of the leasing mechanism described in Section 5.2.3.  The
   following sub-sections describe the <session-info> and <packages>
   elements, as used by the <generalInfo> element.

5.2.5.1.1.1.  <session-info>

   The <session-info> element is included in Consumer requests when an
   update is being made to an existing media resource session.  The
   ability to change and remove an existing media resource session is
   described in more detail in Section 5.2.3.  The element MAY be
   present.

   The <session-info> element has no attributes.

   The <session-info> element has zero or more of the following child
   elements:

   <session-id>:  A unique identifier that explicitly references an
      existing media resource session on the MRB.  The identifier is
      included to update the existing session and is described in more
      detail in Section 5.2.3.

   <seq>:  Used in association with the <session-id> element in a
      subsequent request to update an existing media resource session on
      an MRB.  The <seq> number is incremented from its original value
      returned in response to the initial request for media resources.
      Its value is a non-negative integer that MUST be limited within
      the 0..2^31-1 range.  In the unlikely case that the counter
      increases to reach the highest allowed value, the <seq> value MUST
      be set to 0.  More information about its use is provided in
      Section 5.2.3.

   <action>:  Provides the operation that should be carried out on an
      existing media resource session on an MRB:

      *  The value of 'update' instructs the MRB to attempt to update
         the existing media resource session with the information
         contained in the <ivrInfo> and <mixerInfo> elements.

      *  The value of 'remove' instructs the MRB to attempt to remove
         the existing media resource session.  More information on its
         use is provided in Section 5.2.3.

5.2.5.1.1.2.  <packages>

   The <packages> element provides a list of Media Control Channel
   Framework compliant packages that are required by the Consumer
   client.  The element MAY be present.

   The <packages> element has no attributes.

   The <packages> element has a single child element:

   <package>:  Contains a string representing the Media Control Channel
      Framework package required by the Consumer client.  The <package>
      element can appear multiple times.  A valid value is a Control
      Package name compliant with Section 13.1.1 of [RFC6230].

5.2.5.1.2.  <ivrInfo>

   The <ivrInfo> element provides information for general Consumer
   request information that is IVR specific.  The following sub-sections
   describe the elements of the <ivrInfo> element: <ivr-sessions>,
   <file-formats>, <dtmf>, <tones>, <asr-tts>, <vxml>, <location>,
   <encryption>, <application-data>, <max-prepared-duration>, and
   <file-transfer-modes>.

5.2.5.1.2.1.  <ivr-sessions>

   The <ivr-sessions> element indicates the number of IVR sessions that
   a Consumer client requires from a media resource.  The element MAY be
   present.

   The <ivr-sessions> element has no attributes.

   The <ivr-sessions> element has a single child element:

   <rtp-codec>:  Describes a required codec and the number of sessions
      using that codec.  The <rtp-codec> element has one attribute.  The
      value of the attribute, 'name', is a media type (which can include
      parameters per [RFC6381]).  The <rtp-codec> element has two child
      elements.  The child element <decoding> contains the number of RTP
      sessions required for decoding using the specified codec, and the
      child element <encoding> contains the number of RTP sessions
      required for encoding using the specified codec.

5.2.5.1.2.2.  <file-formats>

   The <file-formats> element provides a list of file formats required
   for the purpose of playing media.  It should be noted that this
   element describes media types and might better have been named
   "media-formats", but due to existing implementations the name
   "file-formats" is being used.  The element MAY be present.

   The <file-formats> element has no attributes.

   The <file-formats> element has a single child element:

   <required-format>:  Has a single attribute, 'name', which provides
      the type of file format that is required.  A valid value is a
      media type that, depending on its definition, can include
      additional parameters (e.g., [RFC6381]).  The <required-format>
      element then has a further child element, <required-file-package>.
      The <required-file-package> element has a single attribute,
      'required-file-package-name', which contains the name of the Media
      Control Channel Framework package, compliant with Section 13.1.1
      of [RFC6230], for which the file format support applies.

5.2.5.1.2.3.  <dtmf>

   The <dtmf> element specifies the required methods to detect DTMF
   tones and to generate them.  The element MAY be present.

   The <dtmf> element has no attributes.

   The <dtmf> element has zero or more of the following child elements:

   <detect>:  Indicates the required support for DTMF detection.  The
      <detect> element has no attributes.  The <detect> element has a
      further child element, <dtmf-type>.  The <dtmf-type> element has
      two attributes: 'name' and 'package'.  The 'name' attribute
      provides the type of DTMF required and is a case-insensitive
      string containing either 'RFC4733' [RFC4733] or 'Media' (detecting
      tones as signals from the audio stream).  The 'package' attribute
      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the DTMF
      type applies.

   <generate>:  Indicates the required support for DTMF generation.  The
      <generate> element has no attributes.  The <generate> element has
      a single child element, <dtmf-type>.  The <dtmf-type> element has
      two attributes: 'name' and 'package'.  The 'name' attribute
      provides the type of DTMF required and is a case-insensitive
      string containing either 'RFC4733' [RFC4733] or 'Media'
      (generating tones as signals in the audio stream).  The 'package'
      attribute provides the name of the Media Control Channel Framework
      package, compliant with Section 13.1.1 of [RFC6230], for which the
      DTMF type applies.

   <passthrough>:  Indicates the required support for passing DTMF
      through without re-encoding.  The <passthrough> element has no
      attributes.  The <passthrough> element then has a further child
      element, <dtmf-type>.  The <dtmf-type> element has two attributes:
      'name' and 'package'.  The 'name' attribute provides the type of
      DTMF required and is a case-insensitive string containing either
      'RFC4733' [RFC4733] or 'Media' (passing tones as signals through
      the audio stream).  The 'package' attribute provides the name of
      the Media Control Channel Framework package, compliant with
      Section 13.1.1 of [RFC6230], for which the DTMF type applies.

5.2.5.1.2.4.  <tones>

   The <tones> element provides requested tones that a Media Server must
   support for IVR.  In particular, the request refers to both support
   for country codes (ISO 3166-1 [ISO.3166-1]) and requested
   functionality (ITU-T Recommendation Q.1950 [ITU-T.Q.1950]).  The
   element MAY be present.

   The <tones> element has no attributes.

   The <tones> element has zero or more of the following child elements:

   <country-codes>:  Describes the requested country codes in relation
      to tones.  The <country-codes> element has no attributes.  The
      <country-codes> element has one child element.  The child element,
      <country-code>, requests a specific country code, compliant with
      the ISO 3166-1 [ISO.3166-1] specification.  The <country-code>
      element has a single attribute, 'package'.  The attribute
      'package' provides the name of the Media Control Channel Framework
      package, compliant with Section 13.1.1 of [RFC6230], in which the
      tones from the specified country code are requested.

   <h248-codes>:  Describes the requested H.248 codes in relation to
      tones.  The <h248-codes> element has no attributes.  The
      <h248-codes> element has one child element.  The child element,
      <h248-code>, requests a specific H.248 code, compliant with the
      ITU-T Recommendation Q.1950 [ITU-T.Q.1950] specification.  The
      codes can be either specific (e.g., cg/dt to only report the Dial
      Tone from the Call Progress Tones package) or generic (e.g., cg/*
      to report all the tones from the Call Progress Tones package),
      using wildcards.  The <h248-code> element has a single attribute,
      'package'.  The attribute 'package' provides the name of the Media
      Control Channel Framework package, compliant with Section 13.1.1
      of [RFC6230], in which the specified codes are requested.

5.2.5.1.2.5.  <asr-tts>

   The <asr-tts> element requests information about the support for
   Automatic Speech Recognition (ASR) and Text-to-Speech (TTS)
   functionality in a Media Server.  The functionality is requested by
   referring to the supported languages (using ISO 639-1 [ISO.639.2002]
   codes) in relation to both ASR and TTS.  The <asr-tts> element has no
   attributes.  The <asr-tts> element has zero or more of the following
   child elements:

   <asr-support>:  Describes the available languages for ASR.  The
      <asr-support> element has no attributes.  The <asr-support>
      element has one child element.  The child element, <language>,

      requests that the Media Server supports ASR for a specific
      language.  The <language> element has a single attribute,
      'xml:lang'.  The attribute 'xml:lang' contains the ISO 639-1
      [ISO.639.2002] code of the supported language.

   <tts-support>:  Describes the available languages for TTS.  The
      <tts-support> element has no attributes.  The <tts-support>
      element has one child element.  The child element, <language>,
      requests that the Media Server supports TTS for a specific
      language.  The <language> element has a single attribute,
      'xml:lang'.  The attribute 'xml:lang' contains the ISO 639-1
      [ISO.639.2002] code of the supported language.

5.2.5.1.2.6.  <vxml>

   The <vxml> element specifies if the Consumer client requires VoiceXML
   and, if so, which protocols are supported (e.g., via the control
   framework, RFC 4240 [RFC4240], or RFC 5552 [RFC5552]).  The element
   MAY be present.

   The <vxml> element has a single child element:

   <vxml-mode>:  Has two attributes: 'package' and 'require'.  The
      'package' attribute provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], for
      which the VXML support applies.  The 'require' attribute specifies
      the type of VXML support required by the Consumer client (e.g.,
      RFC 5552 [RFC5552], RFC 4240 [RFC4240], or IVR Package [RFC6231]),
      and valid values are case-insensitive RFC references (e.g.,
      "rfc6231" to specify that the client requests support for VoiceXML
      as provided by the IVR Package [RFC6231]).

   The presence of at least one <vxml> child element would indicate that
   the Consumer client requires VXML support as specified by the child
   element itself.  An empty <vxml> element would otherwise indicate
   that the Consumer client does not require VXML support.

5.2.5.1.2.7.  <location>

   The <location> element requests a civic location for an IVR Media
   Server.  The request makes use of the Civic Address Schema
   standardized in RFC 5139 [RFC5139].  The element MAY be present.
   More precisely, this section is entirely optional and is
   implementation specific in its level of population.

   The <location> element has no attributes.

   The <location> element has a single child element:

   <civicAddress>:  Describes the civic address location of the
      requested Media Server, whose representation refers to Section 4
      of RFC 5139 [RFC5139].

5.2.5.1.2.8.  <encryption>

   The <encryption> element allows a Consumer client to request support
   for encrypting RTP media streams using RFC 3711 [RFC3711].  The
   element MAY be present.  If the element is present, then the Media
   Server supports DTLS-SRTP [RFC5763].

   The <encryption> element has no attributes.

   The <encryption> element has no child elements.

5.2.5.1.2.9.  <application-data>

   The <application-data> element provides an arbitrary string of
   characters as IVR application-level data.  This data is meant to only
   have meaning at the application-level logic and as such is not
   otherwise restricted by this specification.  The set of allowed
   characters is the same as those in XML (viz., tab, carriage return,
   line feed, and the legal characters of Unicode and ISO/IEC 10646
   [ISO.10646.2012] (see also Section 2.2 of
   <http://www.w3.org/TR/xml/>)).  The element MAY be present.

   The <application-data> element has no attributes.

   The <application-data> element has no child elements.

5.2.5.1.2.10.  <max-prepared-duration>

   The <max-prepared-duration> element indicates the amount of time
   required by the Consumer client representing media dialog preparation
   in the system before it is executed.  The element MAY be present.

   The <max-prepared-duration> element has no attributes.

   The <max-prepared-duration> element has a single child element:

   <max-time>:  Has a single attribute, 'max-time-seconds', which
      provides the amount of time in seconds that a media dialog can be
      in the prepared state.  The <max-time> element then has a further
      child element, <max-time-package>.  The <max-time-package> element

      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the time
      period applies.

5.2.5.1.2.11.  <file-transfer-modes>

   The <file-transfer-modes> element allows the Consumer client to
   specify which scheme names are required for file transfer to a Media
   Server for each Media Control Channel Framework package type.  For
   example, does the Media Server support fetching media resources via
   HTTP, HTTPS, NFS, etc.?  The element MAY be present.

   The <file-transfer-modes> element has no attributes.

   The <file-transfer-modes> element has a single child element:

   <file-transfer-mode>:  Has two attributes: 'name' and 'package'.  The
      'name' attribute provides the scheme name of the protocol required
      for fetching resources: valid values are case-insensitive scheme
      names (e.g., HTTP, HTTPS, NFS, etc.).  The 'package' attribute
      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the scheme
      name applies.

   The same considerations relating to file transfer and live streaming
   are explained further in Section 5.1.5.15 and apply here as well.

5.2.5.1.3.  <mixerInfo>

   The <mixerInfo> element provides information for general Consumer
   request information that is mixer specific.  The following
   sub-sections describe the elements of the <mixerInfo> element:
   <mixers>, <file-formats>, <dtmf>, <tones>, <mixing-modes>,
   <application-data>, <location>, and <encryption>.

5.2.5.1.3.1.  <mixers>

   The <mixers> element provides information detailing the required
   mixed RTP sessions.  The element MAY be present.

   The <mixers> element has no attributes.

   The <mixers> element has a single child element:

   <mix>:  Describes the required mixed RTP sessions.  The <mix> element
      has one attribute.  The value of the attribute, 'users', is the
      number of participants required in the mix.  The <mix> element has

      one child element.  The child element, <rtp-codec>, contains the
      same information relating to RTP sessions as that defined in
      Section 5.1.5.3.  The element MAY be present.

5.2.5.1.3.2.  <file-formats>

   The <file-formats> element provides a list of file formats required
   by the Consumer client for the purpose of playing media to a mix.
   The element MAY be present.

   The <file-formats> element has no attributes.

   The <file-formats> element has a single child element:

   <required-format>:  Has a single attribute, 'name', which provides
      the type of file format supported.  A valid value is a media type
      that, depending on its definition, can include additional
      parameters (e.g., [RFC6381]).  The <required-format> element has a
      child element, <required-file-package>.  The
      <required-file-package> element contains a single attribute,
      'required-file-package-name', which contains the name of the Media
      Control Channel Framework package, compliant with Section 13.1.1
      of [RFC6230], for which the file format support applies.

5.2.5.1.3.3.  <dtmf>

   The <dtmf> element specifies the required methods to detect DTMF
   tones and to generate them in a mix.  The element MAY be present.

   The <dtmf> element has no attributes.

   The <dtmf> element has zero or more of the following child elements:

   <detect>:  Indicates the required support for DTMF detection.  The
      <detect> element has no attributes.  The <detect> element then has
      a further child element, <dtmf-type>.  The <dtmf-type> element has
      two attributes: 'name' and 'package'.  The 'name' attribute
      provides the type of DTMF being used and is a case-insensitive
      string containing either 'RFC4733' [RFC4733] or 'Media' (detecting
      tones as signals from the audio stream).  The 'package' attribute
      provides the name of the Media Control Channel Framework package,
      compliant with Section 13.1.1 of [RFC6230], for which the DTMF
      type applies.

   <generate>:  Indicates the required support for DTMF generation.  The
      <generate> element has no attributes.  The <generate> element has
      a single child element, <dtmf-type>.  The <dtmf-type> element has
      two attributes: 'name' and 'package'.  The 'name' attribute

      provides the type of DTMF being used and is a case-insensitive
      string containing either 'RFC4733' [RFC4733] or 'Media'
      (generating tones as signals in the audio stream).  The 'package'
      attribute provides the name of the Media Control Channel Framework
      package, compliant with Section 13.1.1 of [RFC6230], for which the
      DTMF type applies.

   <passthrough>:  Indicates the required support for passing DTMF
      through without re-encoding.  The <passthrough> element has no
      attributes.  The <passthrough> element has a single child element,
      <dtmf-type>.  The <dtmf-type> element has two attributes: 'name'
      and 'package'.  The 'name' attribute provides the type of DTMF
      being used and is a case-insensitive string containing either
      'RFC4733' [RFC4733] or 'Media' (passing tones as signals through
      the audio stream).  The 'package' attribute provides the name of
      the Media Control Channel Framework package, compliant with
      Section 13.1.1 of [RFC6230], for which the DTMF type applies.

5.2.5.1.3.4.  <tones>

   The <tones> element provides requested tones that a Media Server must
   support for a mix.  In particular, the request refers to both support
   for country codes (ISO 3166-1 [ISO.3166-1]) and requested
   functionality (ITU-T Recommendation Q.1950 [ITU-T.Q.1950]).  The
   element MAY be present.

   The <tones> element has no attributes.

   The <tones> element has zero or more of the following child elements:

   <country-codes>:  Describes the requested country codes in relation
      to tones.  The <country-codes> element has no attributes.  The
      <country-codes> element has a single child element.  The child
      element, <country-code>, requests a specific country code,
      compliant with the ISO 3166-1 [ISO.3166-1] specification.  The
      <country-code> element has a single attribute, 'package'.  The
      attribute 'package' provides the name of the Media Control Channel
      Framework package, compliant with the specification in the related
      IANA registry (e.g., "msc-ivr/1.0"), in which the tones from the
      specified country code are requested.

   <h248-codes>:  Describes the requested H.248 codes with respect to
      tones.  The <h248-codes> element has no attributes.  The
      <h248-codes> element has a single child element.  The child
      element, <h248-code>, requests a specific H.248 code, compliant
      with the ITU-T Recommendation Q.1950 [ITU-T.Q.1950] specification.
      The codes can be either specific (e.g., cg/dt to only report the
      Dial Tone from the Call Progress Tones package) or generic (e.g.,

      cg/* to report all the tones from the Call Progress Tones
      package), using wildcards.  The <h248-code> element has a single
      attribute, 'package'.  The attribute 'package' provides the name
      of the Media Control Channel Framework package, compliant with
      Section 13.1.1 of [RFC6230], in which the specified codes are
      requested.

5.2.5.1.3.5.  <mixing-modes>

   The <mixing-modes> element requests information relating to support
   for audio and video mixing, more specifically a list of supported
   algorithms to mix audio and a list of supported video presentation
   layouts.  The element MAY be present.

   The <mixing-modes> element has no attributes.

   The <mixing-modes> element has zero or more of the following child
   elements:

   <audio-mixing-modes>:  Describes the requested algorithms for audio
      mixing.  The <audio-mixing-modes> element has no attributes.  The
      <audio-mixing-modes> element has one child element.  The child
      element, <audio-mixing-mode>, contains a requested mixing
      algorithm.  Valid values for the <audio-mixing-mode> element are
      algorithm names, e.g., 'nbest' and 'controller' as defined in
      [RFC6505].  The element has a single attribute, 'package'.  The
      attribute 'package' provides the name of the Media Control Channel
      Framework package, compliant with Section 13.1.1 of [RFC6230], for
      which the algorithm support is requested.

   <video-mixing-modes>:  Describes the requested video presentation
      layouts for video mixing.  The <video-mixing-modes> element has
      two attributes: 'vas' and 'activespeakermix'.  The 'vas' attribute
      is of type boolean with a value of 'true' indicating that the
      Consumer client requires automatic Voice Activated Switching.  The
      'activespeakermix' attribute is of type boolean with a value of
      'true' indicating that the Consumer client requires an additional
      video stream for the loudest speaker participant without its
      contribution.  The <video-mixing-modes> element has one child
      element.  The child element, <video-mixing-mode>, contains the
      name of a specific video presentation layout.  The name may refer
      to one of the predefined video layouts defined in the XCON
      conference information data model, or to non-XCON layouts as well,
      as long as they are appropriately prefixed.  The
      <video-mixing-mode> element has a single attribute, 'package'.
      The attribute 'package' provides the name of the Media Control
      Channel Framework package, compliant with Section 13.1.1 of
      [RFC6230], for which the algorithm support is requested.

5.2.5.1.3.6.  <application-data>

   The <application-data> element provides an arbitrary string of
   characters as mixer application-level data.  This data is meant to
   only have meaning at the application-level logic and as such is not
   otherwise restricted by this specification.  The set of allowed
   characters is the same as those in XML (viz., tab, carriage return,
   line feed, and the legal characters of Unicode and ISO/IEC 10646
   [ISO.10646.2012] (see also Section 2.2 of
   <http://www.w3.org/TR/xml/>)).  The element MAY be present.

   The <application-data> element has no attributes.

   The <application-data> element has no child elements.

5.2.5.1.3.7.  <location>

   The <location> element requests a civic location for a mixer Media
   Server.  The request makes use of the Civic Address Schema
   standardized in RFC 5139 [RFC5139].  The element MAY be present.
   More precisely, this section is entirely optional, and it's
   implementation specific to fill it with just the details each
   implementer deems necessary for any optimization that may be needed.

   The <location> element has no attributes.

   The <location> element has a single child element:

   <civicAddress>:  Describes the civic address location of the
      requested Media Server, whose representation refers to Section 4
      of RFC 5139 [RFC5139].

5.2.5.1.3.8.  <encryption>

   The <encryption> element allows a Consumer client to request support
   for encrypting mixed RTP media streams using RFC 3711 [RFC3711].  The
   element MAY be present.  If the element is present, then the Media
   Server supports DTLS-SRTP [RFC5763].

   The <encryption> element has no attributes.

   The <encryption> element has no child elements.

5.2.6.  Media Service Resource Response

   This section provides the element definitions for use in Consumer
   interface responses.  The responses are carried in the
   <mediaResourceResponse> element.

5.2.6.1.  <mediaResourceResponse>

   The <mediaResourceResponse> element provides information for clients
   receiving response information from an external MRB entity.

   The <mediaResourceResponse> element has two mandatory attributes:
   'id' and 'status'.  The 'id' attribute must contain the same value
   that the client provided in the 'id' attribute in the
   <mediaResourceRequest> to which the response is mapped.  The 'status'
   attribute indicates the status code of the operation.  The following
   status codes are defined for 'status':

   +-----------+-------------------------------------------------------+
   | code      | description                                           |
   +-----------+-------------------------------------------------------+
   | 200       | OK                                                    |
   |           |                                                       |
   | 400       | Syntax error                                          |
   |           |                                                       |
   | 405       | Wrong sequence number                                 |
   |           |                                                       |
   | 408       | Unable to find Resource                               |
   |           |                                                       |
   | 409       | Unable to update Resource                             |
   |           |                                                       |
   | 410       | Unable to remove Resource                             |
   |           |                                                       |
   | 420       | Unsupported attribute or element                      |
   +-----------+-------------------------------------------------------+

               Table 2: <mediaResourceResponse> Status Codes

   If a new media resource request made by a client application has been
   accepted, the MRB MUST reply with a <mediaResourceResponse> with
   status code 200.  The same rule applies whenever a request to update
   (action='update') or remove (action='remove') an existing transaction
   can be fulfilled by the MRB.

   A media resource request, nevertheless, may fail for several reasons.
   In such a case, the status codes defined in Table 2 must be used
   instead.  Specifically, if the MRB fails to handle a request due to a
   syntax error in the request itself (e.g., incorrect XML, violation of

   the schema constraints, or invalid values in any of the attributes/
   elements), the MRB MUST reply with a <mediaResourceResponse> with
   status code 400.  If a syntactically correct request fails because
   the request also includes any attribute/element the MRB doesn't
   understand, the MRB MUST reply with a <mediaResourceResponse> with
   status code 420.  If a syntactically correct request fails because it
   contains a wrong sequence number, that is, a 'seq' value not
   consistent with the increment the MRB expects according to
   Section 5.2.3, the MRB MUST reply with a <mediaResourceResponse> with
   status code 405.  If a syntactically correct request fails because
   the MRB couldn't find any Media Server able to fulfill the
   requirements presented by the Application Server in its request, the
   MRB MUST reply with a <mediaResourceResponse> with status code 408.
   If a syntactically correct request fails because the MRB couldn't
   update an existing request according to the new requirements
   presented by the Application Server in its request, the MRB MUST
   reply with a <mediaResourceResponse> with status code 409.  If a
   syntactically correct request fails because the MRB couldn't remove
   an existing request and release the related resources as requested by
   the Application Server, the MRB MUST reply with a
   <mediaResourceResponse> with status code 410.

   Further details on status codes 409 and 410 are included in
   Section 5.2.3, where the leasing mechanism, along with its related
   scenarios, is described in more detail.

   The <mediaResourceResponse> element has <response-session-info> as a
   child element.  This element is used to describe the response of a
   Consumer interface query and is covered in the following sub-section.

5.2.6.1.1.  <response-session-info>

   The <response-session-info> element is included in Consumer
   responses.  This applies to responses to both requests for new
   resources and requests to update an existing media resource session.
   The ability to change and remove an existing media resource session
   is described in more detail in Section 5.2.3.  If the request was
   successful, the <mediaResourceResponse> MUST have one
   <response-session-info> child, which describes the media resource
   session addressed by the request.  If the request was not successful,
   the <mediaResourceResponse> MUST NOT have a <response-session-info>
   child.

   The <response-session-info> element has no attributes.

   The <response-session-info> element has zero or more of the following
   child elements:

   <session-id>:  A unique identifier that explicitly references an
      existing media resource session on the MRB.  The identifier is
      included to update the existing session and is described in more
      detail in Section 5.2.3.

   <seq>:  Used in association with the <session-id> element in a
      subsequent request to update an existing media resource session on
      an MRB.  The <seq> number is incremented from its original value
      returned in response to the initial request for media resources.
      More information on its use is provided in Section 5.2.3.

   <expires>:  Includes the number of seconds that the media resources
      are reserved as part of this interaction.  If the lease is not
      refreshed before expiry, the MRB will reclaim the resources and
      they will no longer be guaranteed.  It is RECOMMENDED that a
      minimum value of 300 seconds be used for the value of the
      'expires' attribute.  It is also RECOMMENDED that a Consumer
      client refresh the lease at an interval that is not too close to
      the expiry time.  A value of 80% of the timeout period could be
      used.  For example, if the timeout period is 300 seconds, the
      Consumer client would refresh the transaction at 240 seconds.
      More information on its use is provided in Section 5.2.3.

   <media-server-address>:  Provides information to reach the Media
      Server handling the requested media resource.  One or more
      instances of these elements may appear.  The
      <media-server-address> element has a single attribute named 'uri',
      which supplies a SIP URI that reaches the specified Media Server.
      It also has three optional elements: <connection-id>,
      <ivr-sessions>, and <mixers>.  The <ivr-sessions> and <mixers>
      elements are defined in Sections 5.2.5.1.2.1 and 5.2.5.1.3.1,
      respectively, and have the same meaning but are applied to
      individual Media Server instances as a subset of the overall
      resources reported in the <connection-id> element.  If multiple
      Media Servers are assigned in an IAMM operation, exactly one
      <media-server-address> element, more specifically the Media Server
      that provided the media dialog or CFW response, will have a
      <connection-id> element.  Additional information relating to the
      use of the <connection-id> element for media dialogs is included
      in Section 6.

5.3.  In-Line Unaware MRB Interface

   An entity acting as an In-line MRB can act in one of two roles for a
   request, as introduced in Section 4.2: the In-line Unaware MRB Mode
   (IUMM) of operation and the In-line Aware MRB Mode (IAMM) of
   operation.  This section further describes IUMM.

   It should be noted that the introduction of an MRB entity into the
   network, as specified in this document, requires interfaces to be
   implemented by those requesting Media Server resources (for example,
   an Application Server).  This applies when using the Consumer
   interface as discussed in Sections 5.2.1 (Query mode) and 5.2.2
   (IAMM).  An MRB entity can also act in a client-unaware mode when
   deployed into the network.  This allows any SIP-compliant client
   entity, as defined by RFC 3261 [RFC3261] and its extensions, to send
   requests to an MRB that in turn will select an appropriate Media
   Server based on knowledge of Media Server resources it currently has
   available transparently to the client entity.  Using an MRB in this
   mode allows for easy migration of current applications and services
   that are unaware of the MRB concept and would simply require a
   configuration change resulting in the MRB being set as a SIP outbound
   proxy for clients requiring media services.

   With IUMM, the MRB may conclude that an assigned media resource is no
   longer needed when it receives a SIP BYE from the Application Server
   or Media Server that ends the SIP dialog that initiated the request.

   As with IAMM, in IUMM the SIP INVITE from the Application Server
   could convey the application/sdp payload to either set up a media
   dialog or a Control Framework Control Channel.  In either case, in
   order to permit the Application Server to associate a media dialog
   with a Control Channel to the same Media Server, using the procedures
   of [RFC6230] Section 6, the MRB should be acting as a SIP proxy (and
   not a B2BUA).  This allows the SIP URI of the targeted Media Server
   to be transparently passed back to the Application Server in the SIP
   response, resulting in a direct SIP dialog between the Application
   Server and the Media Server.

   While IUMM has the least impact on legacy Application Servers, it
   also provides the least versatility.  See Section 8.

6.  MRB Acting as a B2BUA

   An MRB entity can act as a SIP Back-to-Back User Agent (B2BUA) or a
   SIP Proxy Server as defined in RFC 3261 [RFC3261].  When an MRB acts
   as a B2BUA, issues can arise when using Media Control Channel
   packages such as the IVR [RFC6231] and mixer [RFC6505] packages.
   Specifically, the framework attribute 'connectionid' as provided in

   Appendix A ("Common Package Components") of [RFC6230] uses a
   concatenation of the SIP dialog identifiers to be used for
   referencing SIP dialogs within the Media Control Channel.  When a
   request traverses an MRB acting as a B2BUA, the SIP dialog
   identifiers change, and so the 'connectionid' cannot be used as
   intended due to this change.  For this reason, when an MRB wishes to
   act as a SIP B2BUA when handling a request from an Application Server
   to set up a media dialog to a Media Server, it MUST include the
   optional <connection-id> element in a Consumer interface response
   with a value that provides the equivalent for the 'connectionid'
   ('Local Dialog Tag' + 'Remote Dialog Tag') for the far side of the
   B2BUA.  If present, this value MUST be used as the value for the
   'connectionid' in packages where the Common Package Components are
   used.  The <connection-id> element MUST NOT be included in an HTTP
   Consumer interface response.

   It is important to point out that although more Media Server
   instances may be returned in a Consumer response (i.e., the MRB has
   assigned more than one Media Server to a Consumer request to fulfill
   the Application Server requirements), in IAMM the MRB will only act
   as a B2BUA with a single Media Server.  In this case, exactly one
   <media-server-address> element, describing the media dialog or CFW
   response, will have a <connection-id> element that will not be
   included in any additional <media-server-address> elements.

7.  Multimodal MRB Implementations

   An MRB implementation may operate multimodally with a collection of
   Application Server clients all sharing the same pool of media
   resources.  That is, an MRB may be simultaneously operating in Query
   mode, IAMM, and IUMM.  It knows in which mode to act on any
   particular request from a client, depending on the context of the
   request:

   o  If the received request is an HTTP POST message with application/
      mrb-consumer+xml content, then the MRB processes it in Query mode.

   o  If the received request is a SIP INVITE with application/
      mrb-consumer+xml content and application/sdp content, then the MRB
      processes it in IAMM.

   o  If the received request is a SIP INVITE without application/
      mrb-consumer+xml content but with application/sdp content, then
      the MRB processes it in IUMM.

8.  Relative Merits of Query Mode, IAMM, and IUMM

   At a high level, the possible Application Server MRB interactions can
   be distinguished by the following basic types:

   a.  Query mode - the client is requesting the assignment by the MRB
       of suitable Media Server resources;

   b.  IAMM/media dialog - the client is requesting the assignment by
       the MRB of suitable Media Server resources and the establishment
       of a media dialog to one of the Media Servers;

   c.  IAMM/Control Channel - the client is requesting the assignment by
       the MRB of suitable Media Server resources and the establishment
       of a CFW Control Channel to one of the Media Servers;

   d.  IUMM/media dialog - the client is requesting the establishment of
       a media dialog to a Media Server resource;

   e.  IUMM/Control Channel - the client is requesting the establishment
       of a CFW Control Channel to a Media Server resource.

   Each type of interaction has advantages and disadvantages, where such
   considerations relate to the versatility of what the MRB can provide,
   technical aspects such as efficiency in different application
   scenarios, complexity, delay, use with legacy Application Servers, or
   use with the Media Control Channel Framework.  Depending on the
   characteristics of a particular setting that an MRB is intended to
   support, some of the above interaction types may be more appropriate
   than others.  This section provides a few observations on relative
   merits but is not intended to be exhaustive.  Some constraints of a
   given interaction type may be subtle.

   o  Operation with other types of media control: Any of the types of
      interactions work with the mechanisms described in RFC 4240
      [RFC4240] and RFC 5552 [RFC5552] where initial control
      instructions are conveyed in the SIP INVITE from the Application
      Server for the media dialog to the Media Server and subsequent
      instructions may be fetched using HTTP.  Query mode (a), IAMM/
      media dialog (b), and IUMM/media dialog (d) work with the Media
      Server Markup Language (MSML) as per RFC 5707 [RFC5707] or the
      Media Server Control Markup Language (MSCML) as per RFC 5022
      [RFC5022].

   o  As stated previously, IUMM has no interface impacts on an
      Application Server.  When using IUMM, the Application Server does
      not specify the characteristics of the type of media resource it
      requires, as the <mediaResourceRequest> element is not passed to

      the MRB.  For IUMM/media dialog (d), the MRB can deduce an
      appropriate media resource on a best-effort basis using
      information gleaned from examining information in the SIP INVITE.
      This includes the SDP information for the media dialog, or initial
      control information in the SIP Request-URI as per RFC 4240
      [RFC4240].  With IUMM/Control Channel (e), there is even less
      information for the MRB to use.

   o  If using IUMM/Control Channel (e), the subsequent sending of the
      media dialog to the Media Server should not be done using IUMM/
      media dialog.  That is, the SIP signaling to send the media dialog
      to the selected Media Server must be directly between the
      Application Server and that Media Server, and not through the MRB.
      Unless resources can be confidentially identified, the MRB could
      send the media dialog to a different Media Server.  Likewise, if
      using IUMM/media dialog (d), the subsequent establishment of a
      Control Channel should not be done with IUMM/Control Channel (e)
      unless definitive information is available.

   o  Query mode (a) and IAMM/Control Channel (c) lend themselves to
      requesting a pool of media resources (e.g., a number of IVR or
      conferencing ports) in advance of use and retaining use over a
      period of time, independent of whether there are media dialogs to
      those resources at any given moment, whereas the other types of
      interactions do not.  This also applies to making a subsequent
      request to increase or decrease the amount of resources previously
      awarded.

   o  While Query mode (a) and IAMM/Control Channel (c) are the most
      versatile interaction types, the former is completely decoupled
      from the use or non-use of a Control Channel, whereas the latter
      requires the use of a Control Channel.

   o  When Media Control Channel Framework Control Channels are to be
      used in conjunction with the use of an MRB, Query mode (a) would
      typically result in fewer such channels being established over
      time, as compared to IAMM/Control Channel (c).  That is because
      the latter would involve setting up an additional Control Channel
      every time an Application Server has a new request for an MRB for
      media resources.

9.  Examples

   This section provides examples of both the Publish and Consumer
   interfaces.  Both the Query mode and In-line mode are addressed.

   Note that due to RFC formatting conventions, this section often
   splits HTTP, SIP/SDP, and CFW across lines whose content would exceed
   72 characters.  A backslash character marks where this line folding
   has taken place.  This backslash, and its trailing CRLF and
   whitespace, would not appear in the actual protocol contents.  Also
   note that the indentation of the XML content is only provided for
   readability: actual messages will follow strict XML syntax, which
   allows for but does not require indentation.

9.1.  Publish Example

   The following example assumes that a Control Channel has been
   established and synced as described in the Media Control Channel
   Framework ([RFC6230]).

   Figure 9 shows the subscription/notification mechanism the Publish
   interface is based on, as defined in Section 5.1.  The MRB subscribes
   for information at the Media Server (message A1.), and the Media
   Server accepts the subscription (A2.).  Notifications are triggered
   by the Media Server (B1.) and acknowledged by the MRB (B2.).

         MRB                                            MS
          |                                              |
          | A1. CONTROL (MRB subscription)               |
          |--------------------------------------------->|
          |                                   A2. 200 OK |
          |<---------------------------------------------|
          |                                              |
          .                                              .
          .                                              .
          |                                              |
          |                                              |--+ collect
          |                                              |  | up-to-date
          |                                              |<-+ info
          |               B1. CONTROL (MRB notification) |
          |<---------------------------------------------|
          | B2. 200 OK                                   |
          |--------------------------------------------->|
          |                                              |
          .                                              .
          .                                              .

                Figure 9: Publish Example: Sequence Diagram

   The rest of this section includes a full dump of the messages
   associated with the previous sequence diagram, specifically:

   1.  the subscription (A1.), in an <mrbrequest> (CFW CONTROL);

   2.  the Media Server accepting the subscription (A2.), in an
       <mrbresponse> (CFW 200);

   3.  a notification (B1.), in an <mrbnotification> (CFW CONTROL);

   4.  the ack to the notification (B2.), in a framework-level 200
       message (CFW 200).

A1. MRB -> MS (CONTROL, publish request)
----------------------------------------
CFW lidc30BZObiC CONTROL
Control-Package: mrb-publish/1.0
Content-Type: application/mrb-publish+xml
Content-Length: 337

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<mrbpublish version="1.0" xmlns="urn:ietf:params:xml:ns:mrb-publish">
    <mrbrequest>
        <subscription action="create" seqnumber="1" id="p0T65U">
            <expires>600</expires>
            <minfrequency>20</minfrequency>
            <maxfrequency>20</maxfrequency>
        </subscription>
    </mrbrequest>
</mrbpublish>

A2. MRB <- MS (200 to CONTROL, request accepted)
------------------------------------------------
CFW lidc30BZObiC 200
Timeout: 10
Content-Type: application/mrb-publish+xml
Content-Length: 139

<mrbpublish version="1.0" xmlns="urn:ietf:params:xml:ns:mrb-publish">
        <mrbresponse status="200" reason="OK: Request accepted"/>
</mrbpublish>

B1. MRB <- MS (CONTROL, event notification from MS)
---------------------------------------------------
CFW 03fff52e7b7a CONTROL
Control-Package: mrb-publish/1.0
Content-Type: application/mrb-publish+xml
Content-Length: 4226

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <mrbpublish version="1.0"
             xmlns="urn:ietf:params:xml:ns:mrb-publish">
    <mrbnotification seqnumber="1" id="QQ6J3c">
        <media-server-id>a1b2c3d4</media-server-id>
        <supported-packages>
            <package name="msc-ivr/1.0"/>
            <package name="msc-mixer/1.0"/>

            <package name="mrb-publish/1.0"/>
            <package name="msc-example-pkg/1.0"/>
        </supported-packages>
        <active-rtp-sessions>
            <rtp-codec name="audio/basic">
                <decoding>10</decoding>
                <encoding>20</encoding>
            </rtp-codec>
        </active-rtp-sessions>
        <active-mixer-sessions>
            <active-mix conferenceid="7cfgs43">
                <rtp-codec name="audio/basic">
                    <decoding>3</decoding>
                    <encoding>3</encoding>
                </rtp-codec>
            </active-mix>
        </active-mixer-sessions>
        <non-active-rtp-sessions>
            <rtp-codec name="audio/basic">
                <decoding>50</decoding>
                <encoding>40</encoding>
            </rtp-codec>
        </non-active-rtp-sessions>
        <non-active-mixer-sessions>
            <non-active-mix available="15">
                <rtp-codec name="audio/basic">
                    <decoding>15</decoding>
                    <encoding>15</encoding>
                </rtp-codec>
            </non-active-mix>
        </non-active-mixer-sessions>
        <media-server-status>active</media-server-status>
        <supported-codecs>
            <supported-codec name="audio/basic">
                <supported-codec-package name="msc-ivr/1.0">
                    <supported-action>encoding</supported-action>
                    <supported-action>decoding</supported-action>
                </supported-codec-package>
                <supported-codec-package name="msc-mixer/1.0">
                    <supported-action>encoding</supported-action>
                    <supported-action>decoding</supported-action>
                </supported-codec-package>
            </supported-codec>
        </supported-codecs>
        <application-data>TestbedPrototype</application-data>

        <file-formats>
            <supported-format name="audio/x-wav">
                <supported-file-package>
                    msc-ivr/1.0
                </supported-file-package>
            </supported-format>
        </file-formats>
        <max-prepared-duration>
            <max-time max-time-seconds="3600">
                <max-time-package>msc-ivr/1.0</max-time-package>
            </max-time>
        </max-prepared-duration>
        <dtmf-support>
            <detect>
                <dtmf-type package="msc-ivr/1.0" name="RFC4733"/>
                <dtmf-type package="msc-mixer/1.0" name="RFC4733"/>
            </detect>
            <generate>
                <dtmf-type package="msc-ivr/1.0" name="RFC4733"/>
                <dtmf-type package="msc-mixer/1.0" name="RFC4733"/>
            </generate>
            <passthrough>
                <dtmf-type package="msc-ivr/1.0" name="RFC4733"/>
                <dtmf-type package="msc-mixer/1.0" name="RFC4733"/>
            </passthrough>
        </dtmf-support>
        <mixing-modes>
            <audio-mixing-modes>
                <audio-mixing-mode package="msc-ivr/1.0">
                     nbest
                </audio-mixing-mode>
            </audio-mixing-modes>
            <video-mixing-modes activespeakermix="true" vas="true">
                <video-mixing-mode package="msc-mixer/1.0">
                     single-view
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     dual-view
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     dual-view-crop
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     dual-view-2x1
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     dual-view-2x1-crop
                </video-mixing-mode>

                <video-mixing-mode package="msc-mixer/1.0">
                     quad-view
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     multiple-5x1
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     multiple-3x3
                </video-mixing-mode>
                <video-mixing-mode package="msc-mixer/1.0">
                     multiple-4x4
                </video-mixing-mode>
            </video-mixing-modes>
        </mixing-modes>
        <supported-tones>
            <supported-country-codes>
                <country-code package="msc-ivr/1.0">GB</country-code>
                <country-code package="msc-ivr/1.0">IT</country-code>
                <country-code package="msc-ivr/1.0">US</country-code>
            </supported-country-codes>
            <supported-h248-codes>
                <h248-code package="msc-ivr/1.0">cg/*</h248-code>
                <h248-code package="msc-ivr/1.0">biztn/ofque</h248-code>
                <h248-code package="msc-ivr/1.0">biztn/erwt</h248-code>
                <h248-code package="msc-mixer/1.0">conftn/*</h248-code>
            </supported-h248-codes>
        </supported-tones>
        <file-transfer-modes>
            <file-transfer-mode package="msc-ivr/1.0" name="HTTP"/>
        </file-transfer-modes>
        <asr-tts-support>
            <asr-support>
                <language xml:lang="en"/>
            </asr-support>
            <tts-support>
                <language xml:lang="en"/>
            </tts-support>
        </asr-tts-support>
        <vxml-support>
            <vxml-mode package="msc-ivr/1.0" support="RFC6231"/>
        </vxml-support>
        <media-server-location>
            <civicAddress xml:lang="it">
                <country>IT</country>
                <A1>Campania</A1>
                <A3>Napoli</A3>
                <A6>Via Claudio</A6>
                <HNO>21</HNO>

                <LMK>University of Napoli Federico II</LMK>
                <NAM>Dipartimento di Informatica e Sistemistica</NAM>
                <PC>80210</PC>
            </civicAddress>
        </media-server-location>
        <label>TestbedPrototype-01</label>
     <media-server-address>sip:MS1@ms.example.net</media-server-address>
     <encryption/>
    </mrbnotification>
   </mrbpublish>

B2. MRB -> MS (200 to CONTROL)
------------------------------
CFW 03fff52e7b7a 200

9.2.  Consumer Examples

   As specified in Section 5.2, the Consumer interface can be involved
   in two different modes: Query and In-line aware.  When in Query mode,
   Consumer messages are transported in HTTP messages: an example of
   such an approach is presented in Section 9.2.1.  When in In-line
   aware mode, messages are instead transported as part of SIP
   negotiations: considering that SIP negotiations may be related to
   either the creation of a Control Channel or to a User Agent Client
   (UAC) media dialog, two separate examples of such an approach are
   presented in Section 9.2.2.

9.2.1.  Query Example

   The following example assumes that the interested Application Server
   already knows the HTTP URL where an MRB is listening for Consumer
   messages.

   Figure 10 shows the HTTP-based transaction between the Application
   Server (AS, as shown in the figure) and the MRB.  The Application
   Server sends a Consumer request as payload of an HTTP POST message
   (1.), and the MRB provides an answer in an HTTP 200 OK message (2.).
   Specifically, as will be shown in the examples, the Application
   Server is interested in 100 IVR ports: the MRB finds two Media
   Servers that can satisfy the request (one providing 60 ports and the
   other providing 40 ports) and reports them to the Application Server.

     AS                                             MRB
      |                                              |
      | 1. HTTP POST (Consumer request)              |
      |--------------------------------------------->|
      |                                              |
      |                                              |
      |                                              |--+ Parse request
      |                                              |  | and see if any
      |                                              |<-+ MS applies
      |                                              |
      |                2. 200 OK (Consumer response) |
      |<---------------------------------------------|
      |                                              |
      |--+ Parse response and                        |
      |  | start session (SIP/COMEDIA/CFW)           |
      |<-+ with first MS reported by MRB             |
      |                                              |
      .                                              .
      .                                              .

           Figure 10: Consumer Example (Query): Sequence Diagram

   The rest of this section includes a full dump of the messages
   associated with the previous sequence diagram, specifically:

   1.  the Consumer request (1.), in a <mediaResourceRequest> (HTTP
       POST, Content-Type 'application/mrb-consumer+xml');

   2.  the Consumer response (2.), in a <mediaResourceResponse> (HTTP
       200 OK, Content-Type 'application/mrb-consumer+xml').

1. AS -> MRB (HTTP POST, Consumer request)
------------------------------------------
POST /Mrb/Consumer HTTP/1.1
Content-Length: 893
Content-Type: application/mrb-consumer+xml
Host: mrb.example.net:8080
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.0.1 (java 1.5)

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<mrbconsumer version="1.0" xmlns="urn:ietf:params:xml:ns:mrb-consumer">
    <mediaResourceRequest id="gh11x23v">
        <generalInfo>
            <packages>
                <package>msc-ivr/1.0</package>
                <package>msc-mixer/1.0</package>
            </packages>
        </generalInfo>
        <ivrInfo>
            <ivr-sessions>
                <rtp-codec name="audio/basic">
                    <decoding>100</decoding>
                    <encoding>100</encoding>
                </rtp-codec>
            </ivr-sessions>
            <file-formats>
                <required-format name="audio/x-wav"/>
            </file-formats>
            <file-transfer-modes>
                <file-transfer-mode package="msc-ivr/1.0" name="HTTP"/>
            </file-transfer-modes>
        </ivrInfo>
    </mediaResourceRequest>
</mrbconsumer>

2. AS <- MRB (200 to POST, Consumer response)
---------------------------------------------
HTTP/1.1 200 OK
X-Powered-By: Servlet/2.5
Server: Sun GlassFish Communications Server 1.5
Content-Type: application/mrb-consumer+xml;charset=ISO-8859-1
Content-Length: 1133
Date: Mon, 12 Apr 2011 14:59:26 GMT

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<mrbconsumer version="1.0" xmlns="urn:ietf:params:xml:ns:mrb-consumer" >
    <mediaResourceResponse reason="Resource found" status="200"
                           id="gh11x23v">
        <response-session-info>
            <session-id>5t3Y4IQ84gY1</session-id>
            <seq>9</seq>
            <expires>3600</expires>
            <media-server-address
                              uri="sip:MediaServer@ms.example.com:5080">
                <ivr-sessions>
                    <rtp-codec name="audio/basic">
                        <decoding>60</decoding>
                        <encoding>60</encoding>
                    </rtp-codec>
                </ivr-sessions>
            </media-server-address>
            <media-server-address
                       uri="sip:OtherMediaServer@pool.example.net:5080">
                <ivr-sessions>
                    <rtp-codec name="audio/basic">
                        <decoding>40</decoding>
                        <encoding>40</encoding>
                    </rtp-codec>
                </ivr-sessions>
            </media-server-address>
        </response-session-info>
    </mediaResourceResponse>
</mrbconsumer>

   As the example shows, the request and response are associated by
   means of the 'id' attribute (id="gh11x23v").  The MRB has picked '9'
   as the random sequence number that needs to be incremented by the
   Application Server for the subsequent request associated with the
   same session.

   The rest of the scenario is omitted for brevity.  After having
   received the 'mediaResourceResponse', the Application Server has the
   URIs of two Media Servers able to fulfill its media requirements and
   can start a control dialog with one or both of them.

9.2.2.  IAMM Examples

   Two separate examples are presented for the IAMM case: in fact, IAMM
   can take advantage of two different approaches with respect to the
   SIP dialogs to be exploited to carry Consumer messages, i.e., i) a
   SIP control dialog to create a Control Channel, and ii) a UAC media
   dialog to attach to a Media Server.  To make things clearer for the
   reader, the same Consumer request as the one presented in the Query
   mode will be sent, in order to clarify how the behavior of the
   involved parties may differ.

9.2.2.1.  IAMM Example: CFW-Based Approach

   The following example assumes that the interested Application Server
   already knows the SIP URI of an MRB.

   Figure 11 shows the first approach, i.e., SIP-based transactions
   between the Application Server, the MRB, and one Media Server that
   the MRB chooses from the two that are allocated to fulfill the
   request.  The diagram is more complex than before.  This is basically
   a scenario envisaging the MRB as a B2BUA.  The Application Server
   sends a SIP INVITE (1.) containing both a CFW-related SDP and a
   Consumer request (multipart body).  The MRB sends a provisional
   response to the Application Server (2.) and starts working on the
   request.  First of all, it makes use of the Consumer request from the
   Application Server to determine which Media Servers should be
   exploited.  Once the right Media Servers have been chosen (MS1 and
   MS2 in the example), the MRB sends a new SIP INVITE (3.) to one of
   the Media Servers (MS1 in the example) by just including the SDP part
   of the original request.  That Media Server negotiates this INVITE as
   specified in [RFC6230] (4., 5., 6.), providing the MRB with its own
   CFW-related SDP.  The MRB replies to the original Application Server
   INVITE preparing a SIP 200 OK with another multipart body (7.): this
   multipart body includes the Consumer response used by the MRB to
   determine the right Media Servers and the SDP returned by the Media
   Server (MS1) in (5.).  The Application Server finally acknowledges
   the 200 OK (8.), and can start a CFW connection towards that Media
   Server (MS1).  Since the MRB provided the Application Server with two
   Media Server instances to fulfill its requirements, the Application
   Server can use the URI in the <media-server-address> element in the
   <mediaResourceResponse> that describes the other Media Server to
   establish a CFW channel with that Media Server (MS2) as well.

   Please note that to ease the reading of the protocol contents a
   simple '=_Part' is used whenever a boundary for a 'multipart/mixed'
   payload is provided, instead of the actual boundary that would be
   inserted in the SIP messages.

  AS                     MRB                        MS1              MS2
  |                       |                           |                |
  | 1. INVITE             |                           |                |
  | (multipart/mixed)     |                           |                |
  |---------------------->|                           |                |
  |       2. 100 (Trying) |                           |                |
  |<----------------------|                           |                |
  |                       |--+ Extract SDP and        |                |
  |                       |  | MRB payloads; handle   |                |
  |                       |<-+ Consumer request to    |                |
  |                       |    pick MSs (MS1 and MS2) |                |
  |                       |                           |                |
  |                       | 3. INVITE                 |                |
  |                       | (only copy SDP from 1.)   |                |
  |                       |-------------------------->|                |
  |                       |           4. 100 (Trying) |                |
  |                       |<--------------------------|                |
  |                       |                           |--+ Negotiate   |
  |                       |                           |  | CFW Control |
  |                       |                           |<-+ Channel     |
  |                       |                 5. 200 OK |                |
  |                       |<--------------------------|                |
  |                       | 6. ACK                    |                |
  |                       |-------------------------->|                |
  |        Prepare new +--|                           |                |
  |       payload with |  |                           |                |
  |    SDP from MS and +->|                           |                |
  |     Consumer reply    |                           |                |
  |                       |                           |                |
  |             7. 200 OK |                           |                |
  |     (multipart/mixed) |                           |                |
  |<----------------------|                           |                |
  | 8. ACK                |                           |                |
  |---------------------->|                           |                |
  |                       |                           |                |
  |--+ Read Cons. reply   |                           |                |
  |  | and use SDP to     |                           |                |
  |<-+ create CFW Chn.    |                           |                |
  |                       |                           |                |
  |                                                   |                |
  |   Create TCP CFW channel towards MS1 (if needed)  |                |
  |-------------------------------------------------->|                |
  |                                                   |                |

  |<<############## TCP CONNECTION #################>>|                |
  |                                                   |                |
  | CFW SYNC                                          |                |
  |++++++++++++++++++++++++++++++++++++++++++++++++++>|                |
  |                                                   |                |
  .                       .                           .                .
  .                       .                           .                .
  |                                                   |                |
  |   Negotiate SIP control dialog with MS2                            |
  |<------------------------------------------------------------------>|
  |   Create TCP CFW channel towards MS2 as well (if needed)           |
  |------------------------------------------------------------------->|
  |                                                                    |
  |<<######################## TCP CONNECTION ########################>>|
  |                                                                    |
  | CFW SYNC                                                           |
  |+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++>|
  |                                                                    |
  |                       |                           |                |
  .                       .                           .                .
  .                       .                           .                .

   Figure 11: Consumer Example (IAMM/Control Channel): Sequence Diagram

   The rest of this section includes an almost full trace of the
   messages associated with the previous sequence diagram.  Only the
   relevant SIP messages are shown (both the INVITEs and the 200 OKs),
   and only the relevant headers are preserved for brevity (Content-Type
   and multipart-related information).  Specifically:

   1.  the original INVITE (1.) containing both a CFW-related SDP
       (Connection-Oriented Media (COMEDIA) information to negotiate a
       new Control Channel) and a Consumer <mediaResourceRequest>;

   2.  the INVITE sent by the MRB (acting as a B2BUA) to the Media
       Server (3.), containing only the CFW-related SDP from the
       original INVITE;

   3.  the 200 OK sent by the Media Server back to the MRB (5.) to
       complete the CFW-related negotiation (SDP only);

   4.  the 200 OK sent by the MRB back to the Application Server in
       response to the original INVITE (7.), containing both the
       CFW-related information sent by the Media Server and a Consumer
       <mediaResourceRequest> documenting the MRB's decision to use that
       Media Server.

1. AS -> MRB (INVITE multipart/mixed)
-------------------------------------
   [..]
   Content-Type: multipart/mixed;boundary="=_Part"

   =_Part
   Content-Type: application/sdp

   v=0
   o=- 2890844526 2890842807 IN IP4 as.example.com
   s=MediaCtrl
   c=IN IP4 as.example.com
   t=0 0
   m=application 48035 TCP cfw
   a=connection:new
   a=setup:active
   a=cfw-id:vF0zD4xzUAW9
   a=ctrl-package:msc-mixer/1.0
   a=ctrl-package:msc-ivr/1.0

   =_Part
   Content-Type: application/mrb-consumer+xml

   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <mrbconsumer version="1.0"
                xmlns="urn:ietf:params:xml:ns:mrb-consumer">
    <mediaResourceRequest id="pz78hnq1">
        <generalInfo>
            <packages>
                <package>msc-ivr/1.0</package>
                <package>msc-mixer/1.0</package>
            </packages>
        </generalInfo>
        <ivrInfo>
            <ivr-sessions>
                <rtp-codec name="audio/basic">
                    <decoding>100</decoding>
                    <encoding>100</encoding>
                </rtp-codec>
            </ivr-sessions>
            <file-formats>
                <required-format name="audio/x-wav"/>
            </file-formats>
            <file-transfer-modes>
                <file-transfer-mode package="msc-ivr/1.0" name="HTTP"/>
            </file-transfer-modes>
        </ivrInfo>
    </mediaResourceRequest>

   </mrbconsumer>

   =_Part

3. MRB -> MS (INVITE sdp only)
------------------------------
   [..]
   Content-Type: application/sdp

   v=0
   o=- 2890844526 2890842807 IN IP4 as.example.com
   s=MediaCtrl
   c=IN IP4 as.example.com
   t=0 0
   m=application 48035 TCP cfw
   a=connection:new
   a=setup:active
   a=cfw-id:vF0zD4xzUAW9
   a=ctrl-package:msc-mixer/1.0
   a=ctrl-package:msc-ivr/1.0

5. MRB <- MS (200 OK sdp)
-------------------------
   [..]
   Content-Type: application/sdp

   v=0
   o=lminiero 2890844526 2890842808 IN IP4 ms.example.net
   s=MediaCtrl
   c=IN IP4 ms.example.net
   t=0 0
   m=application 7575 TCP cfw
   a=connection:new
   a=setup:passive
   a=cfw-id:vF0zD4xzUAW9
   a=ctrl-package:msc-mixer/1.0
   a=ctrl-package:msc-ivr/1.0
   a=ctrl-package:mrb-publish/1.0
   a=ctrl-package:msc-example-pkg/1.0

7. AS <- MRB (200 OK multipart/mixed)
-------------------------------------
   [..]
   Content-Type: multipart/mixed;boundary="=_Part"

   =_Part
   Content-Type: application/sdp

   v=0
   o=lminiero 2890844526 2890842808 IN IP4 ms.example.net
   s=MediaCtrl
   c=IN IP4 ms.example.net
   t=0 0
   m=application 7575 TCP cfw
   a=connection:new
   a=setup:passive
   a=cfw-id:vF0zD4xzUAW9
   a=ctrl-package:msc-mixer/1.0
   a=ctrl-package:msc-ivr/1.0
   a=ctrl-package:mrb-publish/1.0
   a=ctrl-package:msc-example-pkg/1.0

   =_Part
   Content-Type: application/mrb-consumer+xml

   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <mrbconsumer version="1.0"
                xmlns="urn:ietf:params:xml:ns:mrb-consumer" >
    <mediaResourceResponse reason="Resource found" status="200"
                           id="pz78hnq1">
        <response-session-info>
            <session-id>z1skKYZQ3eFu</session-id>
            <seq>9</seq>
            <expires>3600</expires>
            <media-server-address
                              uri="sip:MediaServer@ms.example.com:5080">
                <connection-id>32pbdxZ8:KQw677BF</connection-id>
                <ivr-sessions>
                    <rtp-codec name="audio/basic">
                        <decoding>60</decoding>
                        <encoding>60</encoding>
                    </rtp-codec>
                </ivr-sessions>
            </media-server-address>
            <media-server-address
                       uri="sip:OtherMediaServer@pool.example.net:5080">
                <ivr-sessions>
                    <rtp-codec name="audio/basic">

                        <decoding>40</decoding>
                        <encoding>40</encoding>
                    </rtp-codec>
                </ivr-sessions>
            </media-server-address>
        </response-session-info>
    </mediaResourceResponse>
   </mrbconsumer>

   =_Part

   As the previous example illustrates, the only difference in the
   response that the MRB provides to the Application Server is in the
   'connection-id' attribute that is added to the first allocated Media
   Server instance: this allows the Application Server to understand
   that the MRB has sent the CFW channel negotiation to that specific
   Media Server and that the connection-id to be used is the one
   provided.  This will be described in more detail in the following
   section for the media dialog-based approach.

   The continuation of the scenario (the Application Server connecting
   to MS1 to start the Control Channel and the related SYNC message, the
   Application Server connecting to MS2 as well later on, all the media
   dialogs being attached to either Media Server) is omitted for
   brevity.

9.2.2.2.  IAMM Example: Media Dialog-Based Approach

   The following example assumes that the interested Application Server
   already knows the SIP URI of an MRB.

   Figure 12 shows the second approach, i.e., SIP-based transactions
   between a SIP client, the Application Server, the MRB, and the Media
   Server that the MRB chooses.  The interaction is basically the same
   as previous examples (e.g., contents of the multipart body), but
   considering that a new party is involved in the communication, the
   diagram is slightly more complex than before.  As before, the MRB
   acts as a B2BUA.  A UAC sends a SIP INVITE to a SIP URI handled by
   the Application Server, since it is interested to its services (1.).
   The Application Server sends a provisional response (2.) and, since
   it doesn't have the resources yet, sends to the MRB a new SIP INVITE
   (3.) containing both the UAC media-related SDP and a Consumer request
   (multipart body).  The MRB sends a provisional response to the
   Application Server (4.) and starts working on the request.  First of
   all, it makes use of the Consumer request from the Application Server
   to determine which Media Servers should be chosen.  Once the Media
   Server has been chosen, the MRB sends a new SIP INVITE to one of the
   Media Servers by including the SDP part of the original request (5.).

   The Media Server negotiates this INVITE as specified in [RFC6230]
   (6., 7., 8.) to allocate the needed media resources to handle the new
   media dialog, eventually providing the MRB with its own media-related
   SDP.  The MRB replies to the original Application Server INVITE
   preparing a SIP 200 OK with a multipart body (9.): this multipart
   body includes the Consumer response from the MRB indicating the
   chosen Media Servers and the SDP returned by the Media Server in
   (7.).  The Application Server finally acknowledges the 200 OK (10.)
   and ends the scenario by eventually providing the UAC with the SDP it
   needs to set up the RTP channels with the chosen Media Server: a
   separate direct SIP control dialog may be initiated by the
   Application Server to the same Media Server in order to set up a
   Control Channel to manipulate the media dialog.

   As with the IAMM/Control Channel example in the prior section, this
   example has the MRB selecting Media Server resources across two Media
   Server instances.  The convention could be that the MRB sent the SIP
   INVITE to the first Media Server in the list provided to the
   Application Server in the Consumer response information.  For the
   sake of brevity, considerations related to connecting to the other
   Media Servers as well are omitted, since they have already been
   addressed in the previous section.

   Please note that to ease the reading of the protocol contents, a
   simple '=_Part' is used whenever a boundary for a 'multipart/mixed'
   payload is provided, instead of the actual boundary that would be
   inserted in the SIP messages.

 UAC              AS                     MRB                          MS
  |               |                       |                           |
  | 1. INVITE     |                       |                           |
  | (media SDP)   |                       |                           |
  |-------------->|                       |                           |
  | 2. 100 Trying |                       |                           |
  |<--------------|                       |                           |
  |               | 3. INVITE             |                           |
  |               | (multipart/mixed)     |                           |
  |               |---------------------->|                           |
  |               |       4. 100 (Trying) |                           |
  |               |<----------------------|                           |
  |               |                       |--+ Extract SDP and        |
  |               |                       |  | MRB payloads; handle   |
  |               |                       |<-+ Consumer request to    |
  |               |                       |    pick Media Servers     |
  |               |                       |                           |
  |               |                       | 5. INVITE                 |
  |               |                       | (only copy SDP from 3.)   |
  |               |                       |-------------------------->|
  |               |                       |           6. 100 (Trying) |
  |               |                       |<--------------------------|
  |               |                       |                        +--|
  |               |                       |    Handle media dialog |  |
  |               |                       |        (connection-id) +->|
  |               |                       |                           |
  |               |                       |                 7. 200 OK |
  |               |                       |<--------------------------|
  |               |                       | 8. ACK                    |
  |               |                       |-------------------------->|
  |               |        Prepare new +--|                           |
  |               |       payload with |  |                           |
  |               |    SDP from MS and +->|                           |
  |               |     Consumer reply    |                           |
  |               |                       |                           |
  |               |             9. 200 OK |                           |
  |               |     (multipart/mixed) |                           |
  |               |<----------------------|                           |
  |               | 10. ACK               |                           |
  |               |---------------------->|                           |
  |               |                       |                           |
  |               |--+ Read Cons. reply   |                           |
  |               |  | and send SDP       |                           |
  |               |<-+ back to UAC        |                           |
  |    11. 200 OK |                       |                           |
  |<--------------|                       |                           |
  | 12. ACK       |                       |                           |
  |-------------->|                       |                           |

  |               |                       |                           |
  |<<*************************** RTP *******************************>>|
  |               |                       |                           |
  |               |--+ Negotiate          |                           |
  |               |  | CFW channel        |                           |
  |               |<-+ towards MS         |                           |
  |               |    (if needed)        |                           |
  .               .                       .                           .
  .               .                       .                           .
  |               |                       |                           |
  |               |                                                   |
  |               |    Create TCP CFW channel towards MS (if needed)  |
  |               |-------------------------------------------------->|
  |               |                                                   |
  |               |<<############## TCP CONNECTION #################>>|
  |               |                                                   |
  |               | CFW SYNC                                          |
  |               |++++++++++++++++++++++++++++++++++++++++++++++++++>|
  |               |                                                   |
  .               .                       .                           .
  .               .                       .                           .

     Figure 12: Consumer Example (IAMM/Media Dialog): Sequence Diagram

   The rest of this section includes a trace of the messages associated
   with the previous sequence diagram.  Only the relevant SIP messages
   are shown (both the INVITEs and the 200 OKs), and only the relevant
   headers are preserved for brevity (Content-Type, From/To, and
   multipart-related information).  Specifically:

   1.  the original INVITE (1.) containing the media-related SDP sent by
       a UAC;

   2.  the INVITE sent by the AS to the MRB (3.), containing both the
       media-related SDP and a Consumer <mediaResourceRequest>;

   3.  the INVITE sent by the MRB (acting as a B2BUA) to the Media
       Server (5.), containing only the media-related SDP from the
       original INVITE;

   4.  the 200 OK sent by the Media Server back to the MRB (7.) to
       complete the media-related negotiation (SDP only);

   5.  the 200 OK sent by the MRB back to the Application Server in
       response to the original INVITE (9.), containing both the
       media-related information sent by the Media Server and a Consumer
       <mediaResourceRequest> documenting the MRB's decision to use that
       Media Server;

   6.  the 200 OK sent by the Application Server back to the UAC to have
       it set up the RTP channel(s) with the Media Server (11.).

1. UAC -> AS (INVITE with media SDP)
------------------------------------
   [..]
   From: <sip:lminiero@users.example.com>;tag=1153573888
   To: <sip:mediactrlDemo@as.example.com>
   [..]
   Content-Type: application/sdp

   v=0
   o=lminiero 123456 654321 IN IP4 203.0.113.2
   s=A conversation
   c=IN IP4 203.0.113.2
   t=0 0
   m=audio 7078 RTP/AVP 0 3 8 101
   a=rtpmap:0 PCMU/8000/1
   a=rtpmap:3 GSM/8000/1
   a=rtpmap:8 PCMA/8000/1
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-11
   m=video 9078 RTP/AVP 98

3. AS -> MRB (INVITE multipart/mixed)
-------------------------------------
   [..]
   From: <sip:ApplicationServer@as.example.com>;tag=fd4fush5
   To: <sip:Mrb@mrb.example.org>
   [..]
   Content-Type: multipart/mixed;boundary="=_Part"

   =_Part
   Content-Type: application/sdp

   v=0
   o=lminiero 123456 654321 IN IP4 203.0.113.2
   s=A conversation
   c=IN IP4 203.0.113.2
   t=0 0

   m=audio 7078 RTP/AVP 0 3 8 101
   a=rtpmap:0 PCMU/8000/1
   a=rtpmap:3 GSM/8000/1
   a=rtpmap:8 PCMA/8000/1
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-11
   m=video 9078 RTP/AVP 98

   =_Part
   Content-Type: application/mrb-consumer+xml

   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <mrbconsumer version="1.0"
                xmlns="urn:ietf:params:xml:ns:mrb-consumer">
    <mediaResourceRequest id="ns56g1x0">
        <generalInfo>
            <packages>
                <package>msc-ivr/1.0</package>
                <package>msc-mixer/1.0</package>
            </packages>
        </generalInfo>
        <ivrInfo>
            <ivr-sessions>
                <rtp-codec name="audio/basic">
                    <decoding>100</decoding>
                    <encoding>100</encoding>
                </rtp-codec>
            </ivr-sessions>
            <file-formats>
                <required-format name="audio/x-wav"/>
            </file-formats>
            <file-transfer-modes>
                <file-transfer-mode package="msc-ivr/1.0" name="HTTP"/>
            </file-transfer-modes>
        </ivrInfo>
    </mediaResourceRequest>
   </mrbconsumer>

   =_Part

5. MRB -> MS (INVITE sdp only)
------------------------------
   [..]
   From: <sip:Mrb@mrb.example.org:5060>;tag=32pbdxZ8
   To: <sip:MediaServer@ms.example.com:5080>
   [..]
   Content-Type: application/sdp

   v=0
   o=lminiero 123456 654321 IN IP4 203.0.113.2
   s=A conversation
   c=IN IP4 203.0.113.2
   t=0 0
   m=audio 7078 RTP/AVP 0 3 8 101
   a=rtpmap:0 PCMU/8000/1
   a=rtpmap:3 GSM/8000/1
   a=rtpmap:8 PCMA/8000/1
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-11
   m=video 9078 RTP/AVP 98

7. MRB <- MS (200 OK sdp)
-------------------------
   [..]
   From: <sip:Mrb@mrb.example.org:5060>;tag=32pbdxZ8
   To: <sip:MediaServer@ms.example.com:5080>;tag=KQw677BF
   [..]
   Content-Type: application/sdp

   v=0
   o=lminiero 123456 654322 IN IP4 203.0.113.1
   s=MediaCtrl
   c=IN IP4 203.0.113.1
   t=0 0
   m=audio 63442 RTP/AVP 0 3 8 101
   a=rtpmap:0 PCMU/8000
   a=rtpmap:3 GSM/8000
   a=rtpmap:8 PCMA/8000
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-15
   a=ptime:20
   a=label:7eda834
   m=video 33468 RTP/AVP 98
   a=rtpmap:98 H263-1998/90000
   a=fmtp:98 CIF=2
   a=label:0132ca2

9. AS <- MRB (200 OK multipart/mixed)
-------------------------------------
   [..]
   From: <sip:ApplicationServer@as.example.com>;tag=fd4fush5
   To: <sip:Mrb@mrb.example.org>;tag=117652221
   [..]
   Content-Type: multipart/mixed;boundary="=_Part"

   =_Part
   Content-Type: application/sdp

   v=0
   o=lminiero 123456 654322 IN IP4 203.0.113.1
   s=MediaCtrl
   c=IN IP4 203.0.113.1
   t=0 0
   m=audio 63442 RTP/AVP 0 3 8 101
   a=rtpmap:0 PCMU/8000
   a=rtpmap:3 GSM/8000
   a=rtpmap:8 PCMA/8000
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-15
   a=ptime:20
   a=label:7eda834
   m=video 33468 RTP/AVP 98
   a=rtpmap:98 H263-1998/90000
   a=fmtp:98 CIF=2
   a=label:0132ca2

   =_Part
   Content-Type: application/mrb-consumer+xml

   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <mrbconsumer version="1.0"
                xmlns="urn:ietf:params:xml:ns:mrb-consumer" >
    <mediaResourceResponse reason="Resource found" status="200"
                           id="ns56g1x0">
        <response-session-info>
            <session-id>z1skKYZQ3eFu</session-id>
            <seq>9</seq>
            <expires>3600</expires>
            <media-server-address
                              uri="sip:MediaServer@ms.example.com:5080">
                <connection-id>32pbdxZ8:KQw677BF</connection-id>
                <ivr-sessions>
                    <rtp-codec name="audio/basic">
                        <decoding>60</decoding>
                        <encoding>60</encoding>

                    </rtp-codec>
                </ivr-sessions>
            </media-server-address>
            <media-server-address
                       uri="sip:OtherMediaServer@pool.example.net:5080">
                <ivr-sessions>
                    <rtp-codec name="audio/basic">
                        <decoding>40</decoding>
                        <encoding>40</encoding>
                    </rtp-codec>
                </ivr-sessions>
            </media-server-address>
        </response-session-info>
    </mediaResourceResponse>
   </mrbconsumer>

   =_Part

11. UAC <- AS (200 OK sdp)
--------------------------
   [..]
   From: <sip:lminiero@users.example.com>;tag=1153573888
   To: <sip:mediactrlDemo@as.example.com>;tag=bcd47c32
   [..]
   Content-Type: application/sdp

   v=0
   o=lminiero 123456 654322 IN IP4 203.0.113.1
   s=MediaCtrl
   c=IN IP4 203.0.113.1
   t=0 0
   m=audio 63442 RTP/AVP 0 3 8 101
   a=rtpmap:0 PCMU/8000
   a=rtpmap:3 GSM/8000
   a=rtpmap:8 PCMA/8000
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-15
   a=ptime:20
   a=label:7eda834
   m=video 33468 RTP/AVP 98
   a=rtpmap:98 H263-1998/90000
   a=fmtp:98 CIF=2
   a=label:0132ca2

   As the examples illustrate, as in the IAMM/Control Channel example,
   the MRB provides the Application Server with a <media-server-address>
   element in the Consumer response: the 'uri' attribute identifies the

   specific Media Server to which the MRB has sent the SDP media
   negotiation, and the 'connection-id' enables the Application Server
   to identify to the Media Server the dialog between the MRB and Media
   Server.  This attribute is needed, since according to the framework
   specification [RFC6230] the connection-id is built out of the From/To
   tags of the dialog between the MRB and Media Server; since the MRB
   acts as a B2BUA in this scenario, without that attribute the
   Application Server does not know the relevant tags, thus preventing
   the CFW protocol from working as expected.

   The continuation of the scenario (the Application Server connecting
   to the Media Server to start the Control Channel, the SYNC message,
   etc.) is omitted for brevity.

10.  Media Service Resource Publisher Interface XML Schema

   This section gives the XML Schema Definition
   [W3C.REC-xmlschema-1-20041028] [W3C.REC-xmlschema-2-20041028] of the
   "application/mrb-publish+xml" format.

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="urn:ietf:params:xml:ns:mrb-publish"
 elementFormDefault="qualified" blockDefault="#all"
 xmlns="urn:ietf:params:xml:ns:mrb-publish"
 xmlns:fw="urn:ietf:params:xml:ns:control:framework-attributes"
 xmlns:ca="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
 xmlns:xsd="http://www.w3.org/2001/XMLSchema">

 <xsd:annotation>
  <xsd:documentation>
   IETF MediaCtrl MRB 1.0

   This is the schema of the IETF MediaCtrl MRB package.

   The schema namespace is urn:ietf:params:xml:ns:mrb-publish

  </xsd:documentation>
 </xsd:annotation>

 <!--
  #############################################################

  SCHEMA IMPORTS

  #############################################################
 -->

 <xsd:import namespace="http://www.w3.org/XML/1998/namespace"
  schemaLocation="http://www.w3.org/2001/xml.xsd">
  <xsd:annotation>
   <xsd:documentation>
    This import brings in the XML attributes for
    xml:base, xml:lang, etc.
   </xsd:documentation>
  </xsd:annotation>
 </xsd:import>

 <xsd:import
  namespace="urn:ietf:params:xml:ns:control:framework-attributes"
  schemaLocation="framework.xsd">
  <xsd:annotation>
   <xsd:documentation>
    This import brings in the framework attributes for
    conferenceid and connectionid.
   </xsd:documentation>
  </xsd:annotation>
 </xsd:import>

 <xsd:import
  namespace="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
  schemaLocation="civicAddress.xsd">
  <xsd:annotation>
   <xsd:documentation>
    This import brings in the civicAddress specification
    from RFC 5139.
   </xsd:documentation>
  </xsd:annotation>
 </xsd:import>

<!--
  #####################################################

  Extensible core type

  #####################################################
 -->

 <xsd:complexType name="Tcore">
  <xsd:annotation>
   <xsd:documentation>
    This type is extended by other (non-mixed) component types to
    allow attributes from other namespaces.
   </xsd:documentation>
  </xsd:annotation>

  <xsd:sequence/>
  <xsd:anyAttribute namespace="##other" processContents="lax" />
 </xsd:complexType>

<!--
  #####################################################

  TOP-LEVEL ELEMENT: mrbpublish

  #####################################################
 -->

<xsd:complexType name="mrbpublishType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
     <xsd:choice>
      <xsd:element ref="mrbrequest" />
      <xsd:element ref="mrbresponse" />
      <xsd:element ref="mrbnotification" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
     </xsd:choice>
    </xsd:sequence>
    <xsd:attribute name="version" type="version.datatype"
      use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="mrbpublish" type="mrbpublishType" />

<!--
  #####################################################

  mrbrequest TYPE

  #####################################################
 -->

<!--  mrbrequest -->

 <xsd:complexType name="mrbrequestType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>

     <xsd:element ref="subscription" />
     <xsd:any namespace="##other" minOccurs="0"
      maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="mrbrequest" type="mrbrequestType" />

<!--  subscription -->

<xsd:complexType name="subscriptionType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
     <xsd:element name="expires" type="xsd:nonNegativeInteger"
      minOccurs="0" maxOccurs="1" />
     <xsd:element name="minfrequency" type="xsd:nonNegativeInteger"
      minOccurs="0" maxOccurs="1" />
     <xsd:element name="maxfrequency" type="xsd:nonNegativeInteger"
      minOccurs="0" maxOccurs="1" />
     <xsd:any namespace="##other" minOccurs="0"
      maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="id" type="id.datatype" use="required" />
    <xsd:attribute name="seqnumber" type="xsd:nonNegativeInteger"
      use="required" />
    <xsd:attribute name="action" type="action.datatype"
      use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="subscription" type="subscriptionType" />

<!--
  #####################################################

  mrbresponse TYPE

  #####################################################
 -->

<!--  mrbresponse -->

 <xsd:complexType name="mrbresponseType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
     <xsd:element ref="subscription" minOccurs="0" maxOccurs="1" />
     <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="status" type="status.datatype"
     use="required" />
    <xsd:attribute name="reason" type="xsd:string" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="mrbresponse" type="mrbresponseType" />

<!--
  #####################################################

  mrbnotification TYPE

  #####################################################
 -->

<!--  mrbnotification -->

<xsd:complexType name="mrbnotificationType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
     <xsd:element name="media-server-id"
        type="subscriptionid.datatype"/>
     <xsd:element ref="supported-packages" minOccurs="0" />
     <xsd:element ref="active-rtp-sessions" minOccurs="0" />
     <xsd:element ref="active-mixer-sessions" minOccurs="0" />

     <xsd:element ref="non-active-rtp-sessions" minOccurs="0" />
     <xsd:element ref="non-active-mixer-sessions" minOccurs="0" />
     <xsd:element ref="media-server-status" minOccurs="0" />
     <xsd:element ref="supported-codecs" minOccurs="0" />
     <xsd:element ref="application-data" minOccurs="0"
      maxOccurs="unbounded" />
     <xsd:element ref="file-formats" minOccurs="0" />
     <xsd:element ref="max-prepared-duration" minOccurs="0" />
     <xsd:element ref="dtmf-support" minOccurs="0" />
     <xsd:element ref="mixing-modes" minOccurs="0" />
     <xsd:element ref="supported-tones" minOccurs="0" />
     <xsd:element ref="file-transfer-modes" minOccurs="0" />
     <xsd:element ref="asr-tts-support" minOccurs="0" />
     <xsd:element ref="vxml-support" minOccurs="0" />
     <xsd:element ref="media-server-location" minOccurs="0" />
     <xsd:element ref="label" minOccurs="0" />
     <xsd:element ref="media-server-address" minOccurs="0" />
     <xsd:element ref="encryption" minOccurs="0" />
     <xsd:any namespace="##other" minOccurs="0"
      maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
     <xsd:attribute name="id" type="subscriptionid.datatype"
      use="required" />
     <xsd:attribute name="seqnumber" type="xsd:nonNegativeInteger"
      use="required" />
     <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="mrbnotification" type="mrbnotificationType" />

<!--  supported-packages -->

 <xsd:complexType name="supported-packagesType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="package" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="supported-packages" type="supported-packagesType"/>

 <xsd:complexType name="packageType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="package" type="packageType" />

<!--  active-rtp-sessions -->

 <xsd:complexType name="active-rtp-sessionsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="rtp-codec" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="active-rtp-sessions" type="active-rtp-sessionsType"/>

 <xsd:complexType name="rtp-codecType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element name="decoding" type="xsd:nonNegativeInteger" />
      <xsd:element name="encoding" type="xsd:nonNegativeInteger" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />

    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="rtp-codec" type="rtp-codecType" />

<!--  active-mixer-sessions -->

<xsd:complexType name="active-mixer-sessionsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="active-mix" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="active-mixer-sessions"
  type="active-mixer-sessionsType" />

<xsd:complexType name="active-mixType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="rtp-codec" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attributeGroup ref="fw:framework-attributes" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="active-mix" type="active-mixType" />

<!--  non-active-rtp-sessions -->

<xsd:complexType name="non-active-rtp-sessionsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="rtp-codec" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="non-active-rtp-sessions"
  type="non-active-rtp-sessionsType" />

<!--  non-active-mixer-sessions -->

<xsd:complexType name="non-active-mixer-sessionsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="non-active-mix" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="non-active-mixer-sessions"
  type="non-active-mixer-sessionsType" />

 <xsd:complexType name="non-active-mixType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="rtp-codec" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="available" type="xsd:nonNegativeInteger"
      use="required" />

    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="non-active-mix" type="non-active-mixType" />

<!--  media-server-status -->

 <xsd:element name="media-server-status" type="msstatus.datatype" />

<!--  supported-codecs -->

<xsd:complexType name="supported-codecsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="supported-codec"
         minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
         maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="supported-codecs" type="supported-codecsType" />

 <xsd:complexType name="supported-codecType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="supported-codec-package"
         minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="supported-codec" type="supported-codecType" />

 <xsd:complexType name="supported-codec-packageType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element name="supported-action" type="actions.datatype"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="supported-codec-package"
  type="supported-codec-packageType" />

<!--  application-data -->

<xsd:element name="application-data" type="appdata.datatype" />

<!--  file-formats -->

<xsd:complexType name="file-formatsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="supported-format"
         minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
         maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="file-formats" type="file-formatsType" />

 <xsd:complexType name="supported-formatType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="supported-file-package"
         minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"

        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="supported-format" type="supported-formatType" />

 <xsd:element name="supported-file-package"
  type="xsd:string" />

<!--  max-prepared-duration -->

<xsd:complexType name="max-prepared-durationType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="max-time" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="max-prepared-duration"
  type="max-prepared-durationType" />

 <xsd:complexType name="max-timeType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element name="max-time-package" type="xsd:string" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="max-time-seconds" type="xsd:nonNegativeInteger"
     use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="max-time" type="max-timeType" />

<!--  dtmf-support -->

<xsd:complexType name="dtmf-supportType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="detect" />
       <xsd:element ref="generate" />
       <xsd:element ref="passthrough" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="dtmf-support" type="dtmf-supportType" />

 <xsd:complexType name="detectType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="dtmf-type"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="detect" type="detectType" />

 <xsd:complexType name="generateType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="dtmf-type"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="generate" type="generateType" />

 <xsd:complexType name="passthroughType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="dtmf-type"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="passthrough" type="passthroughType" />

 <xsd:complexType name="dtmf-typeType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="dtmf.datatype" use="required" />
    <xsd:attribute name="package" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="dtmf-type" type="dtmf-typeType" />

<!--  mixing-modes -->

<xsd:complexType name="mixing-modesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:element ref="audio-mixing-modes"
        minOccurs="0" maxOccurs="1" />
      <xsd:element ref="video-mixing-modes"
        minOccurs="0" maxOccurs="1" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />

   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="mixing-modes" type="mixing-modesType" />

<xsd:complexType name="audio-mixing-modesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="audio-mixing-mode"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="audio-mixing-modes" type="audio-mixing-modesType" />

<xsd:complexType name="audio-mixing-modeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="audio-mixing-mode" type="audio-mixing-modeType" />

<xsd:complexType name="video-mixing-modesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="video-mixing-mode"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:attribute name="vas" type="boolean.datatype"
     default="false" />
   <xsd:attribute name="activespeakermix" type="boolean.datatype"
     default="false" />

   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="video-mixing-modes" type="video-mixing-modesType" />

<xsd:complexType name="video-mixing-modeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="video-mixing-mode" type="video-mixing-modeType" />

<!--  supported-tones -->

<xsd:complexType name="supported-tonesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:element ref="supported-country-codes"
        minOccurs="0" maxOccurs="1" />
      <xsd:element ref="supported-h248-codes"
        minOccurs="0" maxOccurs="1" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="supported-tones" type="supported-tonesType" />

<xsd:complexType name="supported-country-codesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="country-code"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>

   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="supported-country-codes"
  type="supported-country-codesType" />

<xsd:complexType name="country-codeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="country-code" type="country-codeType" />

<xsd:complexType name="supported-h248-codesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="h248-code"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="supported-h248-codes"
  type="supported-h248-codesType" />

<xsd:complexType name="h248-codeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="h248-code" type="h248-codeType" />

<!--  file-transfer-modes -->

 <xsd:complexType name="file-transfer-modesType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="file-transfer-mode"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="file-transfer-modes"
              type="file-transfer-modesType" />

 <xsd:complexType name="file-transfer-modeType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="transfermode.datatype"
     use="required" />
    <xsd:attribute name="package" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>
 <xsd:element name="file-transfer-mode" type="file-transfer-modeType" />

<!--  asr-tts-support -->

<xsd:complexType name="asr-tts-supportType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:element ref="asr-support"
        minOccurs="0" maxOccurs="1" />
      <xsd:element ref="tts-support"
        minOccurs="0" maxOccurs="1" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />

   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="asr-tts-support" type="asr-tts-supportType" />

<xsd:complexType name="asr-supportType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="language"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="asr-support" type="asr-supportType" />

<xsd:complexType name="tts-supportType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="language"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="tts-support" type="tts-supportType" />

<xsd:complexType name="languageType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:attribute ref="xml:lang" />

   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="language" type="languageType" />

<!--  media-server-location -->

<xsd:complexType name="media-server-locationType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element name="civicAddress" type="ca:civicAddress"
                        minOccurs="1" maxOccurs="1" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="media-server-location"
  type="media-server-locationType" />

<!--  vxml-support -->

 <xsd:complexType name="vxml-supportType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="vxml-mode"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="vxml-support" type="vxml-supportType" />

 <xsd:complexType name="vxml-modeType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="package" type="xsd:string" use="required" />
    <xsd:attribute name="support" type="vxml.datatype" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="vxml-mode" type="vxml-modeType" />

<!--  label -->

 <xsd:element name="label" type="label.datatype" />

<!-- media-server-address -->

 <xsd:element name="media-server-address" type="xsd:anyURI" />

<!--  encryption -->

 <xsd:complexType name="encryptionType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="encryption" type="encryptionType" />

<!--
  ####################################################

  DATATYPES

  ####################################################
 -->

 <xsd:simpleType name="version.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="1.0" />
  </xsd:restriction>
 </xsd:simpleType>

<xsd:simpleType name="id.datatype">
  <xsd:restriction base="xsd:NMTOKEN" />
 </xsd:simpleType>

 <xsd:simpleType name="status.datatype">
  <xsd:restriction base="xsd:positiveInteger">
   <xsd:pattern value="[0-9][0-9][0-9]" />
  </xsd:restriction>
 </xsd:simpleType>

 <xsd:simpleType name="msstatus.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="active" />
   <xsd:enumeration value="deactivated" />
   <xsd:enumeration value="unavailable" />
  </xsd:restriction>
 </xsd:simpleType>

 <xsd:simpleType name="action.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="create" />
   <xsd:enumeration value="update" />
   <xsd:enumeration value="remove" />
  </xsd:restriction>
 </xsd:simpleType>

 <xsd:simpleType name="actions.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="encoding" />
   <xsd:enumeration value="decoding" />
   <xsd:enumeration value="passthrough" />
  </xsd:restriction>
 </xsd:simpleType>

 <xsd:simpleType name="appdata.datatype">
  <xsd:restriction base="xsd:string" />
 </xsd:simpleType>

 <xsd:simpleType name="dtmf.datatype">
  <xsd:restriction base="xsd:NMTOKEN"/>
 </xsd:simpleType>

 <xsd:simpleType name="transfermode.datatype">
  <xsd:restriction base="xsd:NMTOKEN" />
 </xsd:simpleType>

 <xsd:simpleType name="boolean.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="true" />
   <xsd:enumeration value="false" />
  </xsd:restriction>
 </xsd:simpleType>

 <xsd:simpleType name="vxml.datatype">
  <xsd:restriction base="xsd:NMTOKEN"/>
 </xsd:simpleType>

 <xsd:simpleType name="label.datatype">
  <xsd:restriction base="xsd:NMTOKEN" />
 </xsd:simpleType>

 <xsd:simpleType name="subscriptionid.datatype">
  <xsd:restriction base="xsd:NMTOKEN" />
 </xsd:simpleType>

</xsd:schema>

11.  Media Service Resource Consumer Interface XML Schema

   This section gives the XML Schema Definition
   [W3C.REC-xmlschema-1-20041028] [W3C.REC-xmlschema-2-20041028] of the
   "application/mrb-consumer+xml" format.

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="urn:ietf:params:xml:ns:mrb-consumer"
 elementFormDefault="qualified" blockDefault="#all"
 xmlns="urn:ietf:params:xml:ns:mrb-consumer"
 xmlns:ca="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
 xmlns:xsd="http://www.w3.org/2001/XMLSchema">

 <xsd:annotation>
  <xsd:documentation>
   IETF MediaCtrl MRB 1.0

   This is the schema of the IETF MediaCtrl MRB Consumer interface.

   The schema namespace is urn:ietf:params:xml:ns:mrb-consumer

  </xsd:documentation>
 </xsd:annotation>

 <!--
  #############################################################

  SCHEMA IMPORTS

  #############################################################
 -->

 <xsd:import namespace="http://www.w3.org/XML/1998/namespace"
  schemaLocation="http://www.w3.org/2001/xml.xsd">
  <xsd:annotation>
   <xsd:documentation>
    This import brings in the XML attributes for
    xml:base, xml:lang, etc.
   </xsd:documentation>
  </xsd:annotation>
 </xsd:import>

 <xsd:import
  namespace="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
  schemaLocation="civicAddress.xsd">
  <xsd:annotation>
   <xsd:documentation>

    This import brings in the civicAddress specification
    from RFC 5139.
   </xsd:documentation>
  </xsd:annotation>
 </xsd:import>

<!--
  #####################################################

  Extensible core type

  #####################################################
 -->

 <xsd:complexType name="Tcore">
  <xsd:annotation>
   <xsd:documentation>
    This type is extended by other (non-mixed) component types to
    allow attributes from other namespaces.
   </xsd:documentation>
  </xsd:annotation>
  <xsd:sequence/>
  <xsd:anyAttribute namespace="##other" processContents="lax" />
 </xsd:complexType>

<!--
  #####################################################

  TOP-LEVEL ELEMENT: mrbconsumer

  #####################################################
 -->

<xsd:complexType name="mrbconsumerType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
     <xsd:choice>
      <xsd:element ref="mediaResourceRequest" />
      <xsd:element ref="mediaResourceResponse" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
     </xsd:choice>
    </xsd:sequence>
    <xsd:attribute name="version" type="version.datatype"
      use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />

   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

 <xsd:element name="mrbconsumer" type="mrbconsumerType" />

<!--
  #####################################################

  mediaResourceRequest TYPE

  #####################################################
 -->

<!--  mediaResourceRequest -->

 <xsd:complexType name="mediaResourceRequestType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="generalInfo" minOccurs="0" />
      <xsd:element ref="ivrInfo" minOccurs="0" />
      <xsd:element ref="mixerInfo" minOccurs="0" />
     <xsd:any namespace="##other" minOccurs="0"
      maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="id" type="xsd:string"
      use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="mediaResourceRequest"
         type="mediaResourceRequestType" />

<!--
  #####################################################

  generalInfo TYPE

  #####################################################
-->

<!--  generalInfo -->

<xsd:complexType name="generalInfoType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="session-info" minOccurs="0" />
      <xsd:element ref="packages" minOccurs="0" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="generalInfo" type="generalInfoType" />

<!--  session-info -->

<xsd:complexType name="session-infoType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element name="session-id" type="id.datatype"/>
       <xsd:element name="seq" type="xsd:nonNegativeInteger"/>
       <xsd:element name="action" type="action.datatype"/>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="session-info" type="session-infoType" />

<!--  packages -->

<xsd:complexType name="packagesType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element name="package" type="xsd:string" minOccurs="0"
        maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="packages" type="packagesType"/>

<!--
  #####################################################

  ivrInfo TYPE

  #####################################################
-->

<!--  ivrInfo -->

<xsd:complexType name="ivrInfoType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="ivr-sessions" minOccurs="0" />
      <xsd:element ref="file-formats" minOccurs="0" />
      <xsd:element ref="dtmf-type" minOccurs="0" />
      <xsd:element ref="tones" minOccurs="0" />
      <xsd:element ref="asr-tts" minOccurs="0" />
      <xsd:element ref="vxml" minOccurs="0" />
      <xsd:element ref="location" minOccurs="0" />
      <xsd:element ref="encryption" minOccurs="0" />
      <xsd:element ref="application-data" minOccurs="0" />
      <xsd:element ref="max-prepared-duration" minOccurs="0" />
      <xsd:element ref="file-transfer-modes" minOccurs="0" />
      <xsd:any namespace="##other" minOccurs="0"
      maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />

   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="ivrInfo" type="ivrInfoType" />

<!--
  #####################################################

  mixerInfo TYPE

  #####################################################
-->

<!--  mixerInfo -->

<xsd:complexType name="mixerInfoType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="mixers" minOccurs="0"/>
      <xsd:element ref="file-formats" minOccurs="0"/>
      <xsd:element ref="dtmf-type" minOccurs="0"/>
      <xsd:element ref="tones" minOccurs="0"/>
      <xsd:element ref="mixing-modes" minOccurs="0"/>
      <xsd:element ref="application-data" minOccurs="0"/>
      <xsd:element ref="location" minOccurs="0"/>
      <xsd:element ref="encryption" minOccurs="0"/>
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="mixerInfo" type="mixerInfoType" />

<!--
  #####################################################

  mediaResourceResponse TYPE

  #####################################################
 -->

<!--  mediaResourceResponse -->

 <xsd:complexType name="mediaResourceResponseType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="response-session-info" minOccurs="0" />
       <xsd:any namespace="##other" minOccurs="0"
          maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="id" type="xsd:string"
     use="required" />
    <xsd:attribute name="status" type="status.datatype"
     use="required" />
    <xsd:attribute name="reason" type="xsd:string" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="mediaResourceResponse"
         type="mediaResourceResponseType" />

<!--
  ####################################################

  ELEMENTS

  ####################################################
 -->

<!--  response-session-info -->

<xsd:complexType name="response-session-infoType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element name="session-id" type="id.datatype"/>
       <xsd:element name="seq" type="xsd:nonNegativeInteger"/>

       <xsd:element name="expires" type="xsd:nonNegativeInteger"/>
       <xsd:element ref="media-server-address"
          minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
         maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="response-session-info"
   type="response-session-infoType" />

<!-- media-server-address -->

<xsd:complexType name="media-server-addressTYPE">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
     <xsd:element name="connection-id" type="xsd:string"
         minOccurs="0" maxOccurs="unbounded" />
     <xsd:element ref="ivr-sessions" minOccurs="0"/>
     <xsd:element ref="mixers" minOccurs="0"/>
     <xsd:any namespace="##other" minOccurs="0"
         maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="uri" type="xsd:anyURI" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="media-server-address"
    type="media-server-addressTYPE" />

<!--  ivr-sessions -->

<xsd:complexType name="ivr-sessionsType">
 <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="rtp-codec" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />

   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="ivr-sessions" type="ivr-sessionsType" />

<xsd:complexType name="rtp-codecType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element name="decoding" type="xsd:nonNegativeInteger" />
      <xsd:element name="encoding" type="xsd:nonNegativeInteger" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="rtp-codec" type="rtp-codecType" />

<!-- file-formats -->

<xsd:complexType name="file-formatsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="required-format"
         minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
         maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="file-formats" type="file-formatsType" />

<xsd:complexType name="required-formatType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="required-file-package"
         minOccurs="0" maxOccurs="unbounded" />

       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="required-format" type="required-formatType" />

<xsd:complexType name="required-file-packageType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element name="required-file-package-name" type="xsd:string"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="required-file-package"
  type="required-file-packageType" />

<!--  dtmf-type -->

<xsd:complexType name="dtmfType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="detect" />
       <xsd:element ref="generate" />
       <xsd:element ref="passthrough" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="dtmf" type="dtmfType" />

<xsd:complexType name="detectType">

  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="dtmf-type"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="detect" type="detectType" />

<xsd:complexType name="generateType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="dtmf-type"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="generate" type="generateType" />

<xsd:complexType name="passthroughType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="dtmf-type"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="passthrough" type="passthroughType" />

<xsd:complexType name="dtmf-typeType">

  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="dtmf.datatype" use="required" />
    <xsd:attribute name="package" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="dtmf-type" type="dtmf-typeType" />

<!--  tones -->

<xsd:complexType name="required-tonesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:element ref="country-codes"
        minOccurs="0" maxOccurs="1" />
      <xsd:element ref="h248-codes"
        minOccurs="0" maxOccurs="1" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="tones" type="required-tonesType" />

<xsd:complexType name="required-country-codesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="country-code"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="country-codes"
   type="required-country-codesType" />

<xsd:complexType name="country-codeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="country-code" type="country-codeType" />

<xsd:complexType name="required-h248-codesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="h248-code"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="h248-codes"
   type="required-h248-codesType" />

<xsd:complexType name="h248-codeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="h248-code" type="h248-codeType" />

<!--  asr-tts -->

<xsd:complexType name="asr-ttsType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>

      <xsd:element ref="asr-support"
        minOccurs="0" maxOccurs="1" />
      <xsd:element ref="tts-support"
        minOccurs="0" maxOccurs="1" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="asr-tts" type="asr-ttsType" />

<xsd:complexType name="asr-supportType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="language"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="asr-support" type="asr-supportType" />

<xsd:complexType name="tts-supportType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="language"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="tts-support" type="tts-supportType" />

<xsd:complexType name="languageType">
 <xsd:complexContent>

  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:attribute ref="xml:lang" />
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="language" type="languageType" />

<!--  vxml -->

<xsd:complexType name="vxmlType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="vxml-mode"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="vxml" type="vxmlType" />

<xsd:complexType name="vxml-modeType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="package" type="xsd:string" use="required" />
    <xsd:attribute name="require" type="vxml.datatype" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="vxml-mode" type="vxml-modeType" />

<!--  location -->

<xsd:complexType name="locationType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:element ref="ca:civicAddress"
                        minOccurs="1" maxOccurs="1" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

<xsd:element name="location" type="locationType" />

<!--  encryption -->

 <xsd:complexType name="encryptionType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
 </xsd:complexType>

 <xsd:element name="encryption" type="encryptionType" />

<!--  application-data -->

<xsd:element name="application-data" type="appdata.datatype" />

<!--  max-prepared-duration -->

<xsd:complexType name="max-prepared-durationType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="max-time" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />

    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="max-prepared-duration"
  type="max-prepared-durationType" />

<xsd:complexType name="max-timeType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element name="max-time-package" type="xsd:string" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="max-time-seconds" type="xsd:nonNegativeInteger"
     use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="max-time" type="max-timeType" />

<!--  file-transfer-modes -->

<xsd:complexType name="file-transfer-modesType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="file-transfer-mode"
        minOccurs="0" maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="file-transfer-modes"
             type="file-transfer-modesType" />

<xsd:complexType name="file-transfer-modeType">

  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="name" type="transfermode.datatype"
     use="required" />
    <xsd:attribute name="package" type="xsd:string" use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="file-transfer-mode" type="file-transfer-modeType" />

<!--  mixers -->

<xsd:complexType name="mixerssessionsType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="mix" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:element name="mixers" type="mixerssessionsType" />

<xsd:complexType name="mixType">
  <xsd:complexContent>
   <xsd:extension base="Tcore">
    <xsd:sequence>
      <xsd:element ref="rtp-codec" minOccurs="0"
        maxOccurs="unbounded" />
       <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
    </xsd:sequence>
    <xsd:attribute name="users" type="xsd:nonNegativeInteger"
     use="required" />
    <xsd:anyAttribute namespace="##other" processContents="lax" />
   </xsd:extension>
  </xsd:complexContent>

</xsd:complexType>

<xsd:element name="mix" type="mixType" />

<!--  mixing-modes -->

<xsd:complexType name="mixing-modesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
      <xsd:element ref="audio-mixing-modes"
        minOccurs="0" maxOccurs="1" />
      <xsd:element ref="video-mixing-modes"
        minOccurs="0" maxOccurs="1" />
      <xsd:any namespace="##other" minOccurs="0"
        maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="mixing-modes" type="mixing-modesType" />

<xsd:complexType name="audio-mixing-modesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="audio-mixing-mode"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="audio-mixing-modes" type="audio-mixing-modesType" />

<xsd:complexType name="audio-mixing-modeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="audio-mixing-mode" type="audio-mixing-modeType" />

<xsd:complexType name="video-mixing-modesType">
 <xsd:complexContent>
  <xsd:extension base="Tcore">
   <xsd:sequence>
     <xsd:element ref="video-mixing-mode"
        minOccurs="0" maxOccurs="unbounded" />
      <xsd:any namespace="##other" minOccurs="0"
       maxOccurs="unbounded" processContents="lax" />
   </xsd:sequence>
   <xsd:attribute name="vas" type="boolean.datatype"
     default="false" />
   <xsd:attribute name="activespeakermix" type="boolean.datatype"
     default="false" />
   <xsd:anyAttribute namespace="##other" processContents="lax" />
  </xsd:extension>
 </xsd:complexContent>
</xsd:complexType>

<xsd:element name="video-mixing-modes" type="video-mixing-modesType" />

<xsd:complexType name="video-mixing-modeType" mixed="true">
 <xsd:sequence>
    <xsd:any namespace="##other" minOccurs="0"
     maxOccurs="unbounded" processContents="lax" />
 </xsd:sequence>
 <xsd:attribute name="package" type="xsd:string" use="required" />
 <xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>

<xsd:element name="video-mixing-mode" type="video-mixing-modeType" />

<!--
  ####################################################

  DATATYPES

  ####################################################
 -->

<xsd:simpleType name="version.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="1.0" />
  </xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="id.datatype">
  <xsd:restriction base="xsd:NMTOKEN" />
</xsd:simpleType>

<xsd:simpleType name="status.datatype">
  <xsd:restriction base="xsd:positiveInteger">
   <xsd:pattern value="[0-9][0-9][0-9]" />
  </xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="transfermode.datatype">
  <xsd:restriction base="xsd:NMTOKEN"/>
</xsd:simpleType>

<xsd:simpleType name="action.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="remove" />
   <xsd:enumeration value="update" />
  </xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="dtmf.datatype">
  <xsd:restriction base="xsd:NMTOKEN"/>
</xsd:simpleType>

<xsd:simpleType name="boolean.datatype">
  <xsd:restriction base="xsd:NMTOKEN">
   <xsd:enumeration value="true" />
   <xsd:enumeration value="false" />
  </xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="vxml.datatype">
  <xsd:restriction base="xsd:NMTOKEN"/>
</xsd:simpleType>

<xsd:simpleType name="appdata.datatype">
  <xsd:restriction base="xsd:string" />
 </xsd:simpleType>

</xsd:schema>

12.  Security Considerations

   The MRB network entity has two primary interfaces -- Publish and
   Consumer -- that carry sensitive information and must therefore be
   appropriately protected and secured.

   The Publish interface, as defined in and described in Section 5.1,
   uses the Media Control Channel Framework [RFC6230] as a mechanism to
   connect an MRB to a Media Server.  It is very important that the
   communication between the MRB and the Media Server is secured: a
   malicious entity may change or even delete subscriptions to a Media
   Server, thus affecting the view the MRB has of the resources actually
   available on a Media Server, leading it to incorrect selection when
   media resources are being requested by an Application Server.  A
   malicious entity may even manipulate available resources on a Media
   Server, for example, to make the MRB think no resources are available
   at all.  Considering that the Publish interface is a CFW Control
   Package, the same security considerations included in the Media
   Control Channel Framework specification apply here to protect
   interactions between an MRB and a Media Server.

   The Publish interface also allows a Media Server, as explained in
   Section 5.1.5.18, to provide more or less accurate information about
   its geographic location, should Application Servers be interested in
   such details when looking for services at an MRB.  While the usage of
   this information is entirely optional and the level of detail to be
   provided is implementation specific, it is important to draw
   attention to the potential security issues that the disclosure of
   such addresses may introduce.  As such, it is important to make sure
   MRB implementations don't disclose this information as is to
   interested Application Servers but only exploit those addresses as
   part of computation algorithms to pick the most adequate resources
   Application Servers may be looking for.

   The Consumer interface, as defined in and described in Section 5.2,
   conceives transactions based on a session ID.  These transactions may
   be transported either by means of HTTP messages or SIP dialogs.  This
   means that malicious users could be able to disrupt or manipulate an
   MRB session should they have access to the above-mentioned session ID
   or replicate it somehow: for instance, a malicious entity could
   modify an existing session between an Application Server and the MRB,
   e.g., requesting less resources than originally requested to cause
   media dialogs to be rejected by the Application Server, or requesting
   many more resources instead to try and lock as many of (if not all)
   the resources an MRB can provide, thus making them unavailable to
   other legitimate Application Servers in subsequent requests.  In
   order to prevent this, it is strongly advised that MRB
   implementations generate session identifiers that are very hard to

   replicate, in order to minimize the chances that malicious users
   could gain access to valid identifiers by just guessing or by means
   of brute-force attacks.  It is very important, of course, to also
   secure the way that these identifiers are transported by the involved
   parties, in both requests and responses, in order to prevent network
   attackers from intercepting Consumer messages and having access to
   session IDs.  The Consumer interface uses either the Hypertext
   Transfer Protocol (HTTP) or the Session Initiation Protocol (SIP) as
   the mechanism for clients to connect to an MRB to request media
   resources.  In the case where HTTP is used, any binding using the
   Consumer interface MUST be capable of being transacted over Transport
   Layer Security (TLS), as described in RFC 2818 [RFC2818].  In the
   case where SIP is used, the same security considerations included in
   the Media Control Channel Framework specification apply here to
   protect interactions between a client requesting media resources and
   an MRB.

   Should a valid session ID be compromised somehow (that is,
   intercepted or just guessed by a malicious user), as a further means
   to prevent disruption the Consumer interface also prescribes the use
   of a sequence number in its transactions.  This sequence number is to
   be increased after each successful transaction, starting from a first
   value randomly generated by the MRB when the session is first
   created, and it must match in every request/response.  While this
   adds complexity to the protocol (implementations must pay attention
   to those sequence numbers, since wrong values will cause "Wrong
   sequence number" errors and the failure of the related requests), it
   is an important added value for security.  In fact, considering that
   different transactions related to the same session could be
   transported in different, unrelated HTTP messages (or SIP INVITEs in
   cases where the In-line mode is being used), this sequence number
   protection prevents the chances of session replication or disruption,
   especially in cases where the session ID has been compromised: that
   is, it should make it harder for malicious users to manipulate or
   remove a session for which they have obtained the session ID.  It is
   strongly advised that the MRB doesn't choose 1 as the first sequence
   number for a new session but rather picks a random value to start
   from.  The reaction to transactions that are out of sequence is left
   to MRB implementations: a related error code is available, but
   implementations may decide to enforce further limitations or actions
   upon the receipt of too many failed attempts in a row or of what
   looks like blatant attempts to guess what the current, valid sequence
   number is.

   It is also worth noting that in In-line mode (both IAMM and IUMM) the
   MRB may act as a Back-to-Back User Agent (B2BUA).  This means that
   when acting as a B2BUA the MRB may modify SIP bodies: it is the case,
   for instance, for the IAMM handling multipart/mixed payloads.  This

   impacts the ability to use any SIP security feature that protects the
   body (e.g., RFC 4474 [RFC4474], S/MIME, etc.), unless the MRB acts as
   a mediator for the security association.  This should be taken into
   account when implementing an MRB compliant with this specification.

   Both the Publishing interface and Consumer interface may address the
   location of a Media Server: the Publishing interface may be used to
   inform the MRB where a Media Server is located (approximately or
   precisely), and the Consumer interface may be used to ask for a Media
   Server located somewhere in a particular region (e.g., a conference
   bridge close to San Francisco).  Both Media Server and MRB
   implementers need to take this into account when deciding whether or
   not to make this location information available, and if so how many
   bits of information really need to be made available for brokering
   purposes.

   It is worthwhile to cover authorization issues related to this
   specification.  Neither the Publishing interface nor the Consumer
   interface provides an explicit means for implementing authentication,
   i.e., they do not contain specific protocol interactions to ensure
   that authorized Application Servers can make use of the services
   provided by an MRB instance.  Considering that both interfaces are
   transported using well-established protocols (HTTP, SIP, CFW),
   support for such functionality can be expressed by means of the
   authentication mechanisms provided by the protocols themselves.
   Therefore, any MRB-aware entity (Application Servers, Media Servers,
   MRBs themselves) MUST support HTTP and SIP Digest access
   authentication.  The usage of such Digest access authentications is
   recommended and not mandatory, which means MRB-aware entities MAY
   exploit it in deployment.

   An MRB may want to enforce further constraints on the interactions
   between an Application Server/Media Server and an MRB.  For example,
   it may choose to only accept requests associated with a specific
   session ID from the IP address that originated the first request or
   may just make use of pre-shared certificates to assess the identity
   of legitimate Application Servers and/or Media Servers.

13.  IANA Considerations

   There are several IANA considerations associated with this
   specification.

13.1.  Media Control Channel Framework Package Registration

   This section registers a new Media Control Channel Framework package,
   per the instructions in Section 13.1 of [RFC6230].

   Package Name:  mrb-publish/1.0

   Published Specification(s):  RFC 6917

   Person and email address to contact for further information:  IETF
      MediaCtrl working group (mediactrl@ietf.org), Chris Boulton
      (chris@ns-technologies.com).

13.2.  application/mrb-publish+xml Media Type

   To:  application

   Subject:  Registration of media type application/mrb-publish+xml

   Type name:  application

   Subtype name:  mrb-publish+xml

   Required parameters:  none

   Optional parameters:  Same as charset parameter of application/xml as
      specified in RFC 3023 [RFC3023].

   Encoding considerations:  Same as encoding considerations of
      application/xml as specified in RFC 3023 [RFC3023].

   Security considerations:  See Section 10 of RFC 3023 [RFC3023] and
      Section 12 of RFC 6917.

   Interoperability considerations:  none.

   Published specification:  Section 10 of RFC 6917.

   Applications that use this media type:  This media type is used to
      support a Media Resource Broker (MRB) entity.

   Additional Information:

      Magic Number:  None

      File Extension:  .xdf

      Macintosh file type code:  "TEXT"

   Person and email address to contact for further information:  Chris
      Boulton (chris@ns-technologies.com).

   Intended usage: COMMON

   Author/Change controller:  The IETF.

13.3.  application/mrb-consumer+xml Media Type

   To:  application

   Subject:  Registration of media type application/mrb-consumer+xml

   Type name:  application

   Subtype name:  mrb-consumer+xml

   Mandatory parameters:  none

   Optional parameters:  Same as charset parameter of application/xml as
      specified in RFC 3023 [RFC3023].

   Encoding considerations:  Same as encoding considerations of
      application/xml as specified in RFC 3023 [RFC3023].

   Security considerations:  See Section 10 of RFC 3023 [RFC3023] and
      Section 12 of RFC 6917.

   Interoperability considerations:  none.

   Published specification:  Section 11 of RFC 6917.

   Applications that use this media type:  This media type is used to
      support a Media Resource Broker (MRB) entity.

   Additional Information:

      Magic Number:  None

      File Extension:  .xdf

      Macintosh file type code:  "TEXT"

   Person and email address to contact for further information:  Chris
      Boulton (chris@ns-technologies.com).

   Intended usage: COMMON

   Author/Change controller:  The IETF.

13.4.  URN Sub-Namespace Registration for mrb-publish

   IANA has registered the URN "urn:ietf:params:xml:ns:mrb-publish",
   with the ID of "mrb-publish".  The schema of the XML namespace named
   urn:ietf:params:xml:ns:mrb-publish is in Section 10.

13.5.  URN Sub-Namespace Registration for mrb-consumer

   IANA has registered the URN "urn:ietf:params:xml:ns:mrb-consumer",
   with the ID of "mrb-consumer".  The schema of the XML namespace named
   urn:ietf:params:xml:ns:mrb-consumer is in Section 11.

13.6.  XML Schema Registration for mrb-publish

   IANA has registered the schema for mrb-publish:

   URI:  urn:ietf:params:xml:schema:mrb-publish

   ID:  mrb-publish

   Filename:  mrb-publish

   Registrant Contact:  IETF MediaCtrl working group
      (mediactrl@ietf.org)

   Schema:  The XML for the schema is in Section 10 of this document.

13.7.  XML Schema Registration for mrb-consumer

   Please register the schema for mrb-consumer:

   URI:  urn:ietf:params:xml:schema:mrb-consumer

   ID:  mrb-consumer

   Filename:  mrb-consumer

   Registrant Contact:  IETF MediaCtrl working group
      (mediactrl@ietf.org)

   Schema:  The XML for the schema is in Section 11 of this document.

14.  Acknowledgements

   The authors would like to thank the members of the Publish Interface
   design team, who provided valuable input into this document.  The
   design team consisted of Adnan Saleem, Michael Trank, Victor
   Paulsamy, Martin Dolly, and Scott McGlashan.  The authors would also
   like to thank John Dally, Bob Epley, Simon Romano, Henry Lum,
   Christian Groves, and Jonathan Lennox for input into this
   specification.

   Ben Campbell carried out the RAI expert review on an early version of
   this specification and provided a great deal of invaluable input.

15.  References

15.1.  Normative References

   [ISO.10646.2012]
              International Organization for Standardization,
              "Information technology -- Universal Coded Character Set
              (UCS)", ISO Standard 10646, 2012.

   [ISO.3166-1]
              International Organization for Standardization, "Codes for
              the representation of names of countries and their
              subdivisions - Part 1: Country codes", ISO Standard
              3166-1:2006, 2006.

   [ISO.639.2002]
              International Organization for Standardization, "Codes for
              the representation of names of languages -- Part 1:
              Alpha-2 code", ISO Standard 639, 2002.

   [ITU-T.Q.1950]
              International Telecommunication Union, "Bearer independent
              call bearer control protocol", ITU-T Recommendation
              Q.1950, December 2002.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
              Types", RFC 3023, January 2001.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC3311]  Rosenberg, J., "The Session Initiation Protocol (SIP)
              UPDATE Method", RFC 3311, October 2002.

   [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
              Norrman, "The Secure Real-time Transport Protocol (SRTP)",
              RFC 3711, March 2004.

   [RFC5139]  Thomson, M. and J. Winterbottom, "Revised Civic Location
              Format for Presence Information Data Format Location
              Object (PIDF-LO)", RFC 5139, February 2008.

   [RFC5763]  Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
              for Establishing a Secure Real-time Transport Protocol
              (SRTP) Security Context Using Datagram Transport Layer
              Security (DTLS)", RFC 5763, May 2010.

   [W3C.REC-xmlschema-1-20041028]
              Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
              "XML Schema Part 1: Structures Second Edition", World Wide
              Web Consortium Recommendation REC-xmlschema-1-20041028,
              October 2004,
              <http://www.w3.org/TR/2004/REC-xmlschema-1-20041028>.

   [W3C.REC-xmlschema-2-20041028]
              Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes
              Second Edition", World Wide Web Consortium
              Recommendation REC-xmlschema-2-20041028, October 2004,
              <http://www.w3.org/TR/2004/REC-xmlschema-2-20041028>.

15.2.  Informative References

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC4240]  Burger, E., Van Dyke, J., and A. Spitzer, "Basic Network
              Media Services with SIP", RFC 4240, December 2005.

   [RFC4474]  Peterson, J. and C. Jennings, "Enhancements for
              Authenticated Identity Management in the Session
              Initiation Protocol (SIP)", RFC 4474, August 2006.

   [RFC4733]  Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF
              Digits, Telephony Tones, and Telephony Signals", RFC 4733,
              December 2006.

   [RFC5022]  Van Dyke, J., Burger, E., and A. Spitzer, "Media Server
              Control Markup Language (MSCML) and Protocol", RFC 5022,
              September 2007.

   [RFC5167]  Dolly, M. and R. Even, "Media Server Control Protocol
              Requirements", RFC 5167, March 2008.

   [RFC5552]  Burke, D. and M. Scott, "SIP Interface to VoiceXML Media
              Services", RFC 5552, May 2009.

   [RFC5567]  Melanchuk, T., "An Architectural Framework for Media
              Server Control", RFC 5567, June 2009.

   [RFC5707]  Saleem, A., Xin, Y., and G. Sharratt, "Media Server Markup
              Language (MSML)", RFC 5707, February 2010.

   [RFC6230]  Boulton, C., Melanchuk, T., and S. McGlashan, "Media
              Control Channel Framework", RFC 6230, May 2011.

   [RFC6231]  McGlashan, S., Melanchuk, T., and C. Boulton, "An
              Interactive Voice Response (IVR) Control Package for the
              Media Control Channel Framework", RFC 6231, May 2011.

   [RFC6381]  Gellens, R., Singer, D., and P. Frojdh, "The 'Codecs' and
              'Profiles' Parameters for "Bucket" Media Types", RFC 6381,
              August 2011.

   [RFC6501]  Novo, O., Camarillo, G., Morgan, D., and J. Urpalainen,
              "Conference Information Data Model for Centralized
              Conferencing (XCON)", RFC 6501, March 2012.

   [RFC6505]  McGlashan, S., Melanchuk, T., and C. Boulton, "A Mixer
              Control Package for the Media Control Channel Framework",
              RFC 6505, March 2012.

Authors' Addresses

   Chris Boulton
   NS-Technologies

   EMail: chris@ns-technologies.com

   Lorenzo Miniero
   Meetecho
   Via Carlo Poerio 89
   Napoli  80100
   Italy

   EMail: lorenzo@meetecho.com

   Gary Munson
   AT&T
   200 Laurel Avenue South
   Middletown, New Jersey  07748
   USA

   EMail: gamunson@gmail.com

 

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