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RFC 5381 - Experience of Implementing NETCONF over SOAP


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Network Working Group                                          T. Iijima
Request for Comments: 5381                                   Y. Atarashi
Category: Informational                                        H. Kimura
                                                               M. Kitani
                                                  Alaxala Networks Corp.
                                                                H. Okita
                                                           Hitachi, Ltd.
                                                            October 2008

              Experience of Implementing NETCONF over SOAP

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

IESG Note

   This document discusses implementation experience of NETCONF over
   SOAP.  Note that Section 2.4 of RFC 4741 states, "A NETCONF
   implementation MUST support the SSH transport protocol mapping".
   Therefore, a NETCONF implementation that only supports the SOAP
   transport described in this document and not (at least) also SSH is
   not in compliance with the NETCONF standards.

Abstract

   This document describes how the authors developed a SOAP (Simple
   Object Access Protocol)-based NETCONF (Network Configuration
   Protocol) client and server.  It describes an alternative SOAP
   binding for NETCONF that does not interoperate with an RFC 4743
   conformant implementation making use of cookies on top of the
   persistent transport connections of HTTP.  When SOAP is used as a
   transport protocol for NETCONF, various kinds of development tools
   are available.  By making full use of these tools, developers can
   significantly reduce their workload.  The authors developed an NMS
   (Network Management System) and network equipment that can deal with
   NETCONF messages sent over SOAP.  This document aims to provide
   NETCONF development guidelines gained from the experience of
   implementing a SOAP-based NETCONF client and server.

Table of Contents

   1. Introduction ....................................................3
      1.1. NETCONF over SOAP ..........................................3
      1.2. Motivation .................................................3
   2. NETCONF Development on Web Services Framework ...................4
      2.1. WSDL as an Interface Description Language ..................5
      2.2. Generation of APIs .........................................5
   3. Architecture of the NETCONF over SOAP Implementation ............5
      3.1. SOAP Implementation in NMS .................................6
           3.1.1. SOAP Parser in NMS ..................................7
           3.1.2. Session Maintenance in NMS ..........................7
      3.2. SOAP Implementation in the Network Equipment ...............8
           3.2.1. SOAP Parser in the Network Equipment ................8
           3.2.2. Session Maintenance in the Network Equipment ........8
   4. Guidelines for Developing NETCONF Clients and Servers ...........8
      4.1. Procedures of Development of NETCONF Clients ...............9
           4.1.1. Developing NETCONF Clients without Eclipse .........10
           4.1.2. Developing NETCONF Clients Using Eclipse ...........11
      4.2. Procedures of Development of NETCONF Servers ..............13
           4.2.1. Developing NETCONF Servers without Eclipse .........14
           4.2.2. Developing NETCONF Servers Using Eclipse ...........15
           4.2.3. Developing NETCONF Servers with C
                  Programming Language ...............................18
   5. Security Considerations ........................................18
   6. Acknowledgements ...............................................18
   7. References .....................................................19
      7.1. Normative References ......................................19
      7.2. Informative References ....................................19

1.  Introduction

1.1.  NETCONF over SOAP

   This document is not a product from the NETCONF WG but a report on
   the experience acquired by individual developers.

   SOAP (Simple Object Access Protocol) was specified in [RFC4743] as
   one of the transport protocols for NETCONF.  It is designed to use
   XML (eXtensible Markup Language) as its description language, which
   is a fundamental messaging technology for Web Services.  For this
   reason, SOAP is well suited to the NETCONF protocol and can be
   deployed widely.

   To develop a SOAP-based NETCONF client and server, several
   development tools are available as open-source software.  The authors
   developed a SOAP-based NETCONF client and server by using available
   development tools.  The SOAP-based NETCONF client was developed by
   utilizing Java APIs (Application Programming Interfaces) that are
   automatically generated from the XSD (XML Schema Definition) file and
   WSDL (Web Services Description Language) file obtained from [RFC4741]
   and [RFC4743], respectively.  The SOAP-based NETCONF client that the
   authors developed acts as an NMS (Network Management System).  The
   SOAP-based NETCONF server that the authors developed runs on network
   equipment and accepts NETCONF messages sent from the NETCONF client.

1.2.  Motivation

   The aim of this document is to describe why the authors believe SOAP
   is practical as a transport protocol for NETCONF when an NMS is
   developed.  When developing an NMS that uses SOAP as its transport
   protocol, development tools and procedures can be used according to
   the Web Services framework.  This document also describes the
   experience of implementing NETCONF over SOAP so that even those who
   have little knowledge of SOAP can start developing a SOAP-based
   NETCONF client and server.

   This document describes an alternative SOAP binding for NETCONF that
   does not interoperate with an RFC 4743 conformant implementation as
   it relies on cookies used on top of the persistent transport
   connections of HTTP.  This is provided for information purposes only
   based on the implementation experience of the authors.

2.  NETCONF Development on Web Services Framework

   SOAP is a fundamental messaging technology for Web Services.
   Therefore, if SOAP is used as a transport protocol for NETCONF, a
   network configuration performed by NETCONF is achieved on the Web
   Services framework.  In this section, the overall architecture of Web
   Services is described.

    +----------------+ +----------------------------+
    |     Format     | |     Register / Search      |
    |                | |                            |
    |      XML       | |           UDDI             |
    |                | |  (Universal Description,   |
    |                | | Discovery and Integration) |
    |                | +----------------------------+
    |                | +----------------------------+ +----------------+
    |                | |    Service Description     | |      API       |
    |                | |                            | |                |
    |                | |           WSDL             | |      JAXM      |
    |                | +----------------------------+ | (Java API for  |
    |                | +----------------------------+ | XML Messaging) |
    |                | |   Fundamental Messaging    | |    JAX-RPC     |
    |                | |                            | | (Java API for  |
    |                | |           SOAP             | |   XML / RPC)   |
    +----------------+ +----------------------------+ +----------------+
                       +----------------------------+
                       |        Transport           |
                       |                            |
                       |       HTTP, HTTPS...       |
                       +----------------------------+

              Figure 1: Overall Architecture of Web Services

   As depicted in Figure 1, peripheral technologies around SOAP/HTTP are
   well developed.  Therefore, if SOAP/HTTP is chosen as a transport
   layer for the NETCONF protocol, the NMS development based on the Web
   Services framework can choose from different optional services and
   might be less expensive based on the use of already available
   services.

2.1.  WSDL as an Interface Description Language

   WSDL [WSDL] defines how SOAP messages are exchanged between Web
   Services entities.  Interfaces of Web Services entities are
   automatically generated by development tools when importing a WSDL
   file.  Interfaces generated in this manner act as APIs.  For the
   development of an NMS, only these APIs are necessary; there is no
   need to use SOAP directly.

   Useful tools that can import a WSDL file are available with SOAP.
   For instance, Apache Axis [Axis] generates an interface from a WSDL
   file and is a widely used SOAP implementation middleware.

2.2.  Generation of APIs

   As described in the previous section, APIs are generated from a WSDL
   file by development tools such as Apache Axis.  Such APIs are in the
   form of a Java library and act as programming interfaces for an NMS.
   By using these APIs, an NMS can send SOAP messages to Web Services
   entities.

3.  Architecture of the NETCONF over SOAP Implementation

   The architecture of the NETCONF over SOAP implementation is shown in
   Figure 2.  A NETCONF implementation residing in an NMS works as a
   NETCONF client while network equipment acts as a NETCONF server.  In
   this document, we call NETCONF-client and NETCONF-server
   implementations a NETCONF application and a NETCONF service provider,
   respectively.  A SOAP implementation may be installed on both the NMS
   and the network equipment.  Each instance of the SOAP implementations
   exchanges SOAP messages based on WSDL, as described in [RFC4743].  If
   Java libraries generated from the WSDL are provided in the NMS,
   engineers can develop a NETCONF application, which configures network
   equipment via the NETCONF protocol, by utilizing the Java library.
   There is no need for engineers to use XML or SOAP directly.

    +---------------------------+   +---------------------------+
    |      NETCONF Client       |   |       NETCONF Server      |
    |           (NMS)           |   |     (Network Equipment)   |
    |  +---------------------+  |   |  +---------------------+  |
    |  | NETCONF application |  |   |  |    NETCONF service  |  |
    |  |                     |  |   |  |       provider      |  |
    |  +---------------------+  |   |  +---------------------+  |
    |  +---------------------+  |   |                           |
    |  |    Java library     |  |   |                           |
    |  +---------------------+  |   |                           |
    |  +---------------------+  |   |  +---------------------+  |
    |  | SOAP Implementation |  |   |  | SOAP Implementation |  |
    |  |    (Apache Axis)    |  |   |  |                     |  |
    |  +---------------------+  |   |  +---------------------+  |
    +-------^----------|--------+   +-------^----------|--------+
            |          |     rpc-request    |          |
            |          +-----  /SOAP    ----+          |
            |                  / HTTP(S)               |
            |                                          |
            |                 rpc-reply                |
            +----------------  /SOAP    ---------------+
                               / HTTP(S)
        Figure 2: Architecture of NETCONF Implementation Using SOAP

   The SOAP implementation in both the NMS and network equipment is
   explained in detail in the following sections.

3.1.  SOAP Implementation in NMS

   Several SOAP implementations appropriate for use in an NMS are
   available today.  Apache Axis is one such widely used implementation.

   Axis works as a SOAP implementation and an NMS-development tool.  For
   instance, WSDL2Java, one of Axis' tools, generates Java-class files
   from a WSDL file.  Another tool called Java2WSDL does the opposite:
   it generates a WSDL file from Java-class files.  Consequently,
   various benefits can be obtained if Axis is introduced as a SOAP
   implementation.

   To develop a NETCONF application that is capable of various functions
   such as releasing log messages, Java-class files generated by the
   Axis tool may be extended by adding more functions.  By utilizing
   these Java libraries, engineers can easily develop NETCONF
   applications.

3.1.1.  SOAP Parser in NMS

   The SOAP Parser function is performed entirely by a SOAP
   implementation such as Apache Axis.

3.1.2.  Session Maintenance in NMS

   When exchanging NETCONF messages between an NMS and network
   equipment, a NETCONF session has to be maintained on both sides, as
   described in [RFC4741].

   In [RFC4743], HTTP is specified as an option of an underlying
   protocol for NETCONF over SOAP.  When HTTP is used for that purpose,
   it is also specified that a NETCONF session state is tied to the
   state of the underlying transport (TCP) connection (just like in
   NETCONF over SSH [RFC4742] and NETCONF over BEEP [RFC4744]).
   However, HTTP itself is a stateless protocol, and many server
   implementations process user requests independently of previous
   requests received over the same transport connection.  To simplify
   implementation of the NETCONF service provider, we used the cookie
   field inside the HTTP header to map incoming requests to NETCONF
   sessions.  Note that this means our implementation actually uses an
   alternative SOAP binding for NETCONF, which does not interoperate
   with RFC 4743 compliant implementations.

   For example, the implemented NETCONF-session maintenance in the NMS
   works as follows.  After the NMS sends a NETCONF hello message to the
   network equipment, the NETCONF service provider in the network
   equipment allocates a session identifier for the NETCONF application
   in the NMS and writes it inside the <session> element of a replying
   NETCONF hello message, as described in [RFC4741].  At the same time,
   the network equipment writes the same value in the cookie field
   inside an HTTP header.  After that, a SOAP message encompassing the
   replying NETCONF hello message is added.  When the NMS receives the
   newly allocated session identifier from the replying NETCONF hello
   message, the NETCONF application stores it and writes it inside a
   <session> element for subsequent NETCONF request messages and in a
   cookie field for subsequent HTTP headers.  By recognizing the session
   identifier in NETCONF request messages and the cookie field in HTTP
   headers, the network equipment can maintain both a NETCONF session
   and the state of an HTTP connection.  The NETCONF session is
   maintained over the maintained state of the HTTP connection.  The
   stored session identifier is erased when the NMS sends a NETCONF
   close-session message and receives a NETCONF response message from
   the network equipment.

3.2.  SOAP Implementation in the Network Equipment

   To accept SOAP messages sent from the NMS, it is also necessary to
   provide SOAP in the network equipment.  As in the case of NMS, some
   free SOAP implementations are available today for installation on
   network equipment.  However, the memory capacity of the network
   equipment might be limited.  Therefore, the SOAP implementation may
   be chosen taking memory capacity into consideration.  In some cases,
   a memory-saving method will be required when implementing SOAP in the
   network equipment.

3.2.1.  SOAP Parser in the Network Equipment

   A SOAP header inside the SOAP envelope is defined as optional.
   Therefore, the module that processes the SOAP header can be omitted
   if the memory capacity in the network equipment is insufficient.  In
   this case, a SOAP parser in the network equipment is allowed to parse
   only mandatory parts of a SOAP envelope.

3.2.2.  Session Maintenance in the Network Equipment

   To maintain NETCONF sessions with the NMS, the NETCONF service
   provider in the network equipment has to provide a session identifier
   to the NMS, as described in [RFC4741].

   For example, the implemented NETCONF-session maintenance in the
   network equipment works as follows.  When the network equipment
   receives a NETCONF hello message from the NMS, the NETCONF service
   provider in the network equipment sets a session identifier inside
   the <session> element of a replying NETCONF hello message, as
   described in [RFC4741].  At the same time, the network equipment also
   sets the same value in the cookie field inside an HTTP header.  After
   that, a SOAP message encompassing the replying NETCONF hello message
   is added.  The cookie field inside the HTTP header is used for
   maintaining the state of the HTTP connection over which the NETCONF-
   session maintenance is ensured.  The network equipment then sends an
   HTTP response message to the NMS.  When the network equipment
   receives a NETCONF close-session message from the NMS, it erases the
   stored session identifier.

4.  Guidelines for Developing NETCONF Clients and Servers

   In the case of SOAP transport mapping, sharing information on the
   kinds of development tools that are available would help developers
   start developing SOAP-based NETCONF clients and servers.  That would
   contribute to the rapid deployment of SOAP-based NETCONF clients and
   servers.

4.1.  Procedures of Development of NETCONF Clients

   To develop a SOAP-based NETCONF client, a stub code may be generated.
   A stub is a library that is generated automatically from WSDL by a
   Web Services tool and that acts as a group of APIs.  When using
   Apache Axis as a Web Services tool, a generated stub is in the form
   of Java APIs.  These Java APIs display interfaces of a Web Service as
   if they are methods capable of configuring a local machine.

   The WSDL file named "netconf-soap_1.0.wsdl", which is selected from
   [RFC4743], specifies NETCONF messages to be exchanged between the
   NETCONF client and server.  These NETCONF messages are the "hello"
   message and "rpc" message.  Therefore, stub codes for creating the
   "hello" message and "rpc" message are generated from "netconf-
   soap_1.0.wsdl".  However, the file "netconf-soap_1.0.wsdl" is not
   sufficient because no service element is specified.

   In "myNetconfService.wsdl", which is also selected from [RFC4743], a
   service element is specified and "netconf-soap_1.0.wsdl" is imported.
   Stub codes generated from those WSDL files are found in files such as
   "Netconf.java", "NetconfLocator.java", and "NetconfBindingStub.java".

   When interfaces are used to operate the NETCONF protocol in the
   manner of "get-config" and "edit-config", for example, an XML schema
   file named "netconf.xsd", which is selected from [RFC4741], is used
   by being imported into "netconf-soap_1.0.wsdl".  Using the XML
   schema, methods of operating the NETCONF protocol are generated in
   files such as "GetConfigType.java" and "EditConfigType.java".

   When interfaces are used to configure network functions at the
   network equipment, a data model of each network function has to be
   defined in the style of an XML schema.  The XML schema may be
   imported into "netconf-soap_1.0.wsdl" in the same manner as that of
   the XML schema in [RFC4741].

   The connection between the NETCONF schema and a data model should be
   made by inserting the following attribute into elements of each data
   model.  This attribute is defined in the XML schema in [RFC4741].

   <xs:attribute name="operation" type="editOperationType"
   default="merge"/>

   Consequently, using "myNetconfService.wsdl" to import "netconf-
   soap_1.0.wsdl", NETCONF schema, and the data model makes it possible
   to generate stub files containing interfaces to configure network
   equipment.

   When stub codes are generated, the development environment may be
   arranged as well.  The development of a Java-based NETCONF client may
   use JDK (Java Development Kit) [JDK] and Apache Axis.  In addition,
   using some IDE (Integrated Development Environment) such as Eclipse
   [Eclipse] with Apache Ant [Ant] and NetBeans [NetBeans] would reduce
   the developer workload significantly.  When Eclipse is used as an
   IDE, first, the library (*.jar files) of Axis has to be added to the
   development project's build path as an external library.  The library
   of Axis acts as a SOAP library, so there is no need to be concerned
   about SOAP messaging when programming a NETCONF client using the
   library of Axis.

4.1.1.  Developing NETCONF Clients without Eclipse

   Given that development of a NETCONF client is carried out in the
   environment of a Windows computer without Eclipse, and that
   "myNetconfService.wsdl" is placed in the "C:\NetconfClient"
   directory, a stub is generated by executing the following command in
   the command prompt.

   C:\NetconfClient>java -classpath .;%AXIS_HOME%\lib\axis.jar;%
   AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar;%AXIS_HOME%
   \lib\commons-logging-1.0.4.jar;%AXIS_HOME%\lib\commons-discovery-
   0.2.jar;%AXIS_HOME%\lib\wsdl4j-1.5.1.jar
   org.apache.axis.wsdl.WSDL2Java -p stub myNetconfService.wsdl

   In the directory where the WSDL file is located, the WSDL2Java
   command is executed.  Locations of each Axis library have to be
   specified.  The environment variable of "AXIS_HOME" is the directory
   where Axis is installed.  By executing the above command, files with
   an extension of "*.java" are generated in the "stub" directory, which
   is specified by the above command.  Inside the stub directory, we can
   find files such as "NetconfBindingStub.java", "Hello.java", and
   "GetConfigType.java".

   Next, it is necessary to compile these files by executing the
   following command in the command prompt.

   C:\NetconfClient>javac -classpath .;%AXIS_HOME%\lib\axis.jar;%
   AXIS_HOME%\lib\jaxrpc.jar stub/*.java

   After the compilation of those java files, "*.class" files are
   generated.  After the compiling is done, the source code of the
   NETCONF client has to be written.  Sample source code of the NETCONF
   client is shown in Figure 3.  This NETCONF client is written by
   utilizing stub classes and interfaces, which are imported into the
   local package and referenced.

   import org.apache.axis.types.UnsignedInt;
   import org.apache.axis.types.*;

   public class NetconfClient {
           /**
            * @param args
            */
           public static void main(String[] args) {
                   // TODO Auto-generated method stub
                   try{
                           NetconfClient client = new NetconfClient();
                           java.net.URL url = new java.net.URL(args[0]);
                           stub.Netconf netconf =
                                   new stub.NetconfLocator();
                           stub.NetconfPortType stubNetconf =
                                   netconf.getnetconfPort(url);

                           URI[] uri = new URI[1];
                           stub.holders.HelloCapabilitiesHolder
                           capability = new
                           stub.holders.HelloCapabilitiesHolder(uri);

                           UnsignedInt id = new UnsignedInt();
                           id.setValue(1);
                           org.apache.axis.holders.UnsignedIntHolder
                           holder = new
                           org.apache.axis.holders.UnsignedIntHolder(id)
                           ;
                           stubNetconf.hello(capability, holder);
                   }catch(Exception e){
                           e.printStackTrace();
                   }
           }
   }

              Figure 3: Sample Source Code of NETCONF Clients

   To add functions such as the release of log messages, these functions
   have to be incorporated at this stage.  Again, the NETCONF client is
   developed by compiling its source codes.

4.1.2.  Developing NETCONF Clients Using Eclipse

   When we use Eclipse and Apache Ant, the procedures described in the
   previous section are significantly simplified and executed at one
   time.  In this case, files named "build.xml" and "build.properties"
   are required for Apache Ant.

   The file named "build.xml" is written in XML and seen by Apache Ant
   when Apache Ant is running on Eclipse.  The file specifies how Apache
   Ant behaves.  According to the descriptions of the file, Apache Ant
   compiles source codes, generates JAR (Java ARchive) file, and so on.
   On the other hand, the file named "build.properties" specifies
   properties of the development environment where Apache Ant runs.
   This file is referred to by the "build.xml" file.

   Examples of "build.xml" and "build.properties" are shown in Figure 4
   and Figure 5, respectively.

   <?xml version="1.0"?>
   <project name="NetconfClient" default="all" basedir=".">
           <property file="build.properties"/>
           <path id="axis-classpath">
                   <fileset dir="${axis.libdir}">
                           <include name="*.jar"/>
                   </fileset>
           </path>
           <target name="prepare">
                   <mkdir dir="${destdir}"/>
           </target>
           <target name="stub" depends="prepare">
                   <java classname="org.apache.axis.wsdl.WSDL2Java" fork
                           ="Yes">
                           <arg value="-o"/>
                           <arg value="${srcdir}"/>
                           <arg value="-p"/>
                           <arg value="${stub.stubdir}"/>
                           <arg value="${stub.wsdlpath}"/>
                           <classpath refid="axis-classpath"/>
                   </java>
           </target>
           <target name="compile" depends="stub">
                   <javac srcdir="${srcdir}" destdir="${destdir}"
                           encoding="UTF-8">
                           <classpath refid="axis-classpath"/>
                   </javac>
           </target>
           <target name="stub-jar" depends="compile">
                   <jar jarfile="${stub.jar}" basedir="${destdir}"/>
           </target>
           <target name="all" depends="stub-jar"/>
   </project>

                  Figure 4: build.xml of NETCONF Clients

   axis.libdir=C:/axis-1_4/lib
   srcdir=src
   destdir=classes
   stub.stubdir=stub
   stub.wsdlpath=myNetconfService.wsdl
   stub.jar=NETCONF.jar

               Figure 5: build.properties of NETCONF Clients

   The location of the WSDL file should be specified in the
   "build.properties" file.  In the case shown in Figure 5, the location
   of the WSDL file is specified as being under the current directory.

   By running Apache Ant on Eclipse, the steps specified in Figure 4 are
   taken.  First, stub codes are generated.  Then, compiling of those
   stub codes is executed.  We were careful about the encoding style
   used for the compiling.  After the compilation, Apache Ant will
   generate a JAR file, which is the output that compresses all stub
   files (*.class) and acts as a library.  In this example, the name
   "NETCONF.jar" is specified in Figure 5.  The "NETCONF.jar" file also
   has to be added to the build path of the development project as an
   external library.

   After the "NETCONF.jar" file is added to the build path of the
   development project, source codes of the NETCONF client can be
   written by utilizing stub classes and interfaces.  Source codes like
   the one shown in Figure 3 can be written.  By running Apache Ant
   again, the source code of the NETCONF client is compiled.  The
   NETCONF client is developed in this manner.

4.2.  Procedures of Development of NETCONF Servers

   In the Web Services framework, there are two approaches for
   developing a Web Services provider, namely a NETCONF server.  One is
   called the top-down approach, and the other is called the bottom-up
   approach.  The top-down approach is carried out by first designing a
   WSDL file.  A skeleton source code from the WSDL file is then
   generated by using a Web Services tool such as Apache Axis.  The
   generated skeleton code is just a template of the Web Services
   provider's source code.  Therefore, even though the Web Services
   provider's skeleton code works on its own, if additional functions
   were necessary, the generated skeleton code would require additional
   source codes.  This approach is superior to the bottom-up approach in
   terms of interoperability because the specification is already
   defined in the WSDL file.  All vendors have to be in compliance with
   the WSDL file.

   In contrast, the bottom-up approach is carried out by first creating
   Web Services from source code (e.g., Java bean) and then generating a
   WSDL file from the source code by using a Web Services tool such as
   Axis.  This approach is faster and easier than the top-down approach.
   However, in the bottom-up approach, it is difficult to ensure
   interoperability since implementation of a Web Services becomes
   vendor-specific.

   When developing a NETCONF server, the WSDL file is already defined in
   [RFC4743], so there is no choice but to develop the NETCONF server
   using the top-down approach.  The remainder of this section describes
   the top-down approach for developing a NETCONF server.

   To develop a SOAP-based NETCONF server using the top-down approach, a
   skeleton code is necessary.  A skeleton is a library, which is also
   generated automatically from WSDL by a Web Services tool.  When using
   Axis as a Web Services tool, the generated skeleton is in the form of
   a Java library.  From the same WSDL file as that used for generating
   the stub code, skeleton codes are generated in files such as
   "NetconfBindingSkeleton.java", "Hello.java", and
   "GetConfigType.java".

   When skeleton codes are being generated, the development environment
   may be arranged as well.  Moreover, when a Java-based NETCONF server
   is being developed, in addition to JDK and Axis, a servlet container
   such as Apache Tomcat [Tomcat] is necessary.  The "webapps\axis"
   directory under the Axis directory has to be copied to the "webapps"
   directory under the Tomcat directory.

4.2.1.  Developing NETCONF Servers without Eclipse

   Given that the development environment of a NETCONF server is created
   in the environment of a Windows computer without Eclipse and
   "myNetconfService.wsdl" is placed in the "C:\NetconfServer"
   directory, a skeleton is generated by executing the following command
   in the command prompt.

   C:\NetconfServer>java -classpath .;%AXIS_HOME%\lib\axis.jar;%
   AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar;%AXIS_HOME%
   \lib\commons-logging-1.0.4.jar;%AXIS_HOME%\lib\commons-discovery-
   0.2.jar;%AXIS_HOME%\lib\wsdl4j-1.5.1.jar
   org.apache.axis.wsdl.WSDL2Java -p skeleton -s -S true -d Session
   myNetconfService.wsdl

   In the directory where the WSDL file is located, a WSDL2Java command
   is executed.  Locations of each Axis library should be specified.
   The environment variable of "AXIS_HOME" is a directory where Axis is
   installed.  By executing the above command, files with an extension

   of "*.java" are generated in the "skeleton" directory, which is
   specified in the above command.  Inside the skeleton directory, files
   such as "NetconfBindingSkeleton.java", "Hello.java", and
   "GetConfigType.java" exist.  Furthermore, files named "deploy.wsdd"
   and "undeploy.wsdd" are found.  "Deploy.wsdd" and "undeploy.wsdd" are
   used when deploying a NETCONF server in a servlet container and when
   undeploying a NETCONF server from a servlet container, respectively.

   Adding source codes of NETCONF server functions to skeleton codes
   such as "NetconfBindingImpl.java" is required as the need arises.
   Functions such as the release of log messages have to be added at
   this stage.  After that, by executing the following command in the
   command prompt, compilation of java files is carried out.  Doing so
   will generate "*.class" files.

   C:\NetconfServer>javac -classpath .;%AXIS_HOME%\lib\axis.jar;%
   AXIS_HOME%\lib\jaxrpc.jar skeleton/*.java

   A NETCONF server can be developed by following the above-described
   procedures.  These class files should be copied into the directory
   "webapps\axis\WEB-INFO\classes" of the Apache Tomcat directory.
   Finally, the NETCONF server is deployed by executing the following
   command.

   C:\NetconfServer>java -classpath .;%AXIS_HOME%\lib\axis.jar;%
   AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar;%AXIS_HOME%
   \lib\commons-logging-1.0.4.jar;%AXIS_HOME%\lib\commons-discovery-
   0.2.jar org.apache.axis.client.AdminClient -p 832 depoy.wsdd

   The command is executed in the directory where "deploy.wsdd" is
   located.  The file "deploy.wsdd" is generated at the same time the
   skeleton code is generated.  After deployment, the NETCONF server
   receives NETCONF messages sent from the NETCONF client.

4.2.2.  Developing NETCONF Servers Using Eclipse

   When Eclipse and Apache Ant are used, the procedures described in the
   previous section are significantly simplified and executed at one
   time.  Files named "build.xml" and "build.properties" are required
   for Apache Ant.  Examples of "build.xml" and "build.properties" are
   shown in Figure 6 and Figure 7, respectively.

   <?xml version="1.0"?>
   <project name="NetconfService" default="all" basedir=".">
           <property file="build.properties"/>
           <path id="axis-classpath">
                   <fileset dir="${axis.libdir}">
                           <include name="*.jar"/>
                   </fileset>
           </path>
           <target name="prepare">
                   <mkdir dir="${srcdir}"/>
                   <mkdir dir="${destdir}"/>
           </target>
           <target name="skeleton" depends="prepare">
                   <java classname="org.apache.axis.wsdl.WSDL2Java" fork
                           ="Yes">
                           <arg value="-p"/>
                           <arg value="${skeletondir}"/>
                           <arg value="-o"/>
                           <arg value="${srcdir}"/>
                           <arg value="-s"/>
                           <arg value="-S"/>
                           <arg value="true"/>
                           <arg value="-d"/>
                           <arg value="Session"/>
                           <arg value="${wsdlpath}"/>
                           <classpath refid="axis-classpath"/>
                   </java>
           </target>
           <target name="compile" depends="skeleton">
                   <javac srcdir="${srcdir}" destdir="${destdir}"
                           encoding="UTF-8">
                           <classpath refid="axis-classpath"/>
                   </javac>
           </target>
           <target name="copy2axis" depends="compile">
                   <copy todir="${tomcat.axis.classesdir}" overwrite=
                           "true">
                           <fileset dir="${destdir}">
                                   <include name="*.class"/>
                                   <include name="*/*.class"/>
                                   <include name="*/*/*.class"/>
                           </fileset>
                   </copy>
           </target>
           <target name="deploy" depends="copy2axis">
                   <java classname="org.apache.axis.client.AdminClient"
                           fork="Yes">
                           <arg value="-p"/>

                           <arg value="${deploy.port}"/>
                           <arg value="${deploy.ddname}"/>
                           <classpath refid="axis-classpath"/>
                   </java>
           </target>
           <target name="all" depends="deploy"/>
   </project>

                  Figure 6: build.xml of NETCONF Servers

   axis.libdir=C:/axis-1_4/lib
   tomcat.axis.classesdir=
   C:/Program Files/Apache Software Foundation/Tomcat 6.0/
   webapps/axis/WEB-INF/classes
   srcdir=src
   destdir=classes
   skeletondir=skeleton
   wsdlpath=myNetconfService.wsdl
   deploy.port=832
   deploy.ddname=src/skeleton/deploy.wsdd

               Figure 7: build.properties of NETCONF Servers

   The locations of the WSDL file and "deploy.wsdd" file have to be
   specified in the "build.properties" file.  In Figure 7, the location
   of the WSDL file and "deploy.wsdd" file are specified as being under
   the current directory.

   By running Apache Ant on Eclipse, the steps shown in Figure 6 are
   followed.  First, skeleton codes have to be generated.  After the
   skeleton codes are generated, source codes of the NETCONF server
   functions may be added to the skeleton codes according to the
   functions that developers intend to add.

   Then, by running Apache Ant again, compiling of the skeleton codes is
   executed.  As a result, class files of the NETCONF server are
   generated.  Apache Ant copies these class files to the directory of
   Tomcat and deploys the NETCONF server.  After that, the NETCONF
   server becomes accessible by the NETCONF client.

4.2.3.  Developing NETCONF Servers with C Programming Language

   When the NETCONF server for network equipment is being implemented,
   memory capacity might be limited, so it might not be possible to
   install a Java environment on the network equipment.  The network-
   equipment platform might not support a Web Services tool.  In that
   case, it may be necessary to implement SOAP as well as the NETCONF
   server by using C programming language on the network equipment.

   To develop a NETCONF server capable of receiving NETCONF messages
   sent over SOAP/HTTP, the network equipment may have an HTTP daemon
   and a NETCONF service provider.  A commonly used HTTP daemon can be
   used.  A SOAP module may be added to the HTTP daemon as a connector
   between the HTTP daemon and the NETCONF service provider.  The
   NETCONF service provider for parsing NETCONF messages sent from the
   NETCONF client and sending reply NETCONF messages toward the NETCONF
   client may be developed.

   When an HTTP daemon receives a SOAP message that is sent over HTTP,
   the message is handed over to the SOAP module incorporated in the
   HTTP daemon.  Then, the SOAP module removes the SOAP header and
   passes NETCONF messages to the NETCONF service provider.  After that,
   the NETCONF service provider parses the NETCONF messages and
   configures the network equipment accordingly.

5.  Security Considerations

   The security considerations of [RFC4741] and [RFC4743] are applicable
   in this document.  Implementers or users of SOAP-based NETCONF
   clients and servers should take these considerations into account.

   As specified in the security considerations section of [RFC4743],
   transport-level security, such as authentication of users and
   encryption of transport protocol, has to be ensured by TLS (Transport
   Layer Security) in the case of NETCONF SOAP binding.  That is,
   security has to be provided in the form of NETCONF/SOAP/HTTPS.

6.  Acknowledgements

   Extensive input was received from the members of the NETCONF design
   team, including: Andy Bierman, Simon Leinen, Bert Wijnen, Mehmet
   Ersue, Ted Goddard, Ray Atarashi, Ron Bonica, and Dan Romascanu.  The
   following people have also reviewed this document and provided
   valuable input: Jari Arkko, Pasi Eronen, Chris Newman, Tim Polk,
   David Ward, Magnus Westerlund, and Christian Vogt.

7.  References

7.1.  Normative References

   [RFC4741]   Enns, R., "NETCONF Configuration Protocol", RFC 4741,
               December 2006.

   [RFC4743]   Goddard, T., "Using NETCONF over the Simple Object Access
               Protocol (SOAP)", RFC 4743, December 2006.

7.2.    Informative References

   [Ant]       "Apache Ant".
               <http://ant.apache.org/>

   [Axis]      "Web Services - Axis".
               <http://ws.apache.org/axis/>

   [Eclipse]   "Eclipse".
               <http://www.eclipse.org/>

   [JDK]       "Java SE".
               <http://java.sun.com/javase/index.jsp>

   [NetBeans]  "NetBeans".
               <http://www.netbeans.org/index.html>

   [RFC4742]   Wasserman, M. and T. Goddard, "Using the NETCONF
               Configuration Protocol over Secure SHell (SSH)",
               RFC 4742, December 2006.

   [RFC4744]   Lear, E. and K. Crozier, "Using the NETCONF Protocol over
               the Blocks Extensible Exchange Protocol (BEEP)",
               RFC 4744, December 2006.

   [Tomcat]    "Apache Tomcat".
               <http://tomcat.apache.org/>

   [WSDL]      "Web Service Description Language (WSDL) 1.1".
               <http://www.w3.org/TR/wsdl>

Authors' Addresses

   Iijima Tomoyuki
   Alaxala Networks Corp.
   Shin-Kawasaki Mitsui Bldg.
   890 Saiwai-ku Kashimada
   Kawasaki, Kanagawa  212-0058
   Japan

   Phone: +81-44-549-1735
   Fax:   +81-44-549-1272
   EMail: tomoyuki.iijima@alaxala.com

   Yoshifumi Atarashi
   Alaxala Networks Corp.
   Shin-Kawasaki Mitsui Bldg.
   890 Saiwai-ku Kashimada
   Kawasaki, Kanagawa  212-0058
   Japan

   Phone: +81-44-549-1735
   Fax:   +81-44-549-1272
   EMail: atarashi@alaxala.net

   Hiroyasu Kimura
   Alaxala Networks Corp.
   Shin-Kawasaki Mitsui Bldg.
   890 Saiwai-ku Kashimada
   Kawasaki, Kanagawa  212-0058
   Japan

   Phone: +81-44-549-1735
   Fax:   +81-44-549-1272
   EMail: h-kimura@alaxala.net

   Makoto Kitani
   Alaxala Networks Corp.
   Shin-Kawasaki Mitsui Bldg.
   890 Saiwai-ku Kashimada
   Kawasaki, Kanagawa  212-0058
   Japan

   Phone: +81-44-549-1735
   Fax:   +81-44-549-1272
   EMail: makoto.kitani@alaxala.com

   Hideki Okita
   Hitachi, Ltd.
   1-280 Higashi-Koigakubo
   Kokubunji, Tokyo  185-8601
   Japan

   Phone: +81-42-323-1111
   Fax:   +81-42-327-7868
   EMail: hideki.okita.pf@hitachi.com

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