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RFC 1835 - Architecture of the WHOIS++ service


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Network Working Group                                         P. Deutsch
Request for Comments: 1835              BUNYIP INFORMATION SYSTEMS, Inc.
Category: Standards Track                                    R. Schoultz
                                                                  KTHNOC
                                                            P. Faltstrom
                                        BUNYIP INFORMATION SYSTEMS, Inc.
                                                               C. Weider
                                        BUNYIP INFORMATION SYSTEMS, Inc.
                                                             August 1995

                  Architecture of the WHOIS++ service

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   This document describes WHOIS++, an extension to the trivial WHOIS
   service described in RFC 954 to permit WHOIS-like servers to make
   available more structured information to the Internet.  We describe
   an extension to the simple WHOIS data model and query protocol and a
   companion extensible, distributed indexing service.  A number of
   options have also been added such as the use of multiple languages
   and character sets, more advanced search expressions, structured data
   and a number of other useful features.  An optional authentication
   mechanism for protecting all or part of the associated WHOIS++
   information database from unauthorized access is also described.

Table of Contents

   Part I - WHOIS++ Overview .................................  3
   1.1.  Purpose and Motivation ..............................  3
   1.2.  Basic Information Model .............................  4
   1.2.1.  Changes to the current WHOIS Model ................  5
   1.2.2.  Registering WHOIS++ servers .......................  5
   1.2.3.  The WHOIS++ Search Selection Mechanism ............  7
   1.2.4.  The WHOIS++ Architecture ..........................  7
   1.3.  Indexing in WHOIS++ .................................  8
   1.4.  Getting Help ........................................  9
   1.4.1.  Minimum HELP Required .............................  9
   1.5.  Options and Constraints ............................. 10
   1.6.  Formatting Responses ................................ 10

   1.7.  Reporting Warnings and Errors ....................... 11
   1.8.  Privacy and Security Issues ......................... 11
   Part II - WHOIS++ Implementation .......................... 12
   2.1.  The WHOIS++ interaction model ....................... 12
   2.2.  The WHOIS++ Command set ............................. 12
   2.2.1.  System Commands ................................... 13
   2.2.1.1.  The COMMANDS command ............................ 14
   2.2.1.2.  The CONSTRAINTS command ......................... 15
   2.2.1.3.  The DESCRIBE command ............................ 15
   2.2.1.4.  The HELP command ................................ 15
   2.2.1.5.  The LIST command ................................ 15
   2.2.1.6.  The POLLED-BY command ........................... 15
   2.2.1.7.  The POLLED-FOR command .......................... 16
   2.2.1.8.  The SHOW command ................................ 16
   2.2.1.9.  The VERSION command ............................. 16
   2.2.2.  The Search Command ................................ 16
   2.2.2.1.  Format of a Search Term ......................... 17
   2.2.2.2.  Format of a Search String ....................... 18
   2.3.  WHOIS++ Constraints ................................. 19
   2.3.1.  Required Constraints .............................. 20
   2.3.2.  Optional CONSTRAINTS .............................. 21
   2.3.2.1.  The SEARCH Constraint ........................... 22
   2.3.2.2.  The FORMAT Constraint ........................... 22
   2.3.2.3.  The MAXFULL Constraint .......................... 22
   2.3.2.4.  The MAXHITS Constraint .......................... 23
   2.3.2.5.  The CASE Constraint ............................. 23
   2.3.2.6.  The AUTHENTICATE Constraint ..................... 23
   2.3.2.7.  The NAME Constraint ............................. 23
   2.3.2.8.  The PASSWORD Constraint ......................... 23
   2.3.2.9.  The LANGUAGE Constraint ......................... 23
   2.3.2.10.  The INCHARSET Constraint ....................... 24
   2.3.2.11.  The IGNORE Constraint .......................... 24
   2.3.2.12.  The INCLUDE Constraint ......................... 24
   2.4.  Server Response Modes ............................... 24
   2.4.1.  Default Responses ................................. 25
   2.4.2.  Format of Responses ............................... 25
   2.4.3.  Syntax of a Formatted Response .................... 26
   2.4.3.1.  A FULL format response .......................... 26
   2.4.3.2.  ABRIDGED Format Response ........................ 27
   2.4.3.3.  HANDLE Format Response .......................... 27
   2.4.3.4.  SUMMARY Format Response ......................... 27
   2.4.3.5.  SERVERS-TO-ASK Response ......................... 28
   2.4.4.  System Generated Messages ......................... 28
   2.5.  Compatibility with Older WHOIS Servers .............. 29
   3.  Miscellaneous ......................................... 29
   3.1.  Acknowledgements .................................... 29
   3.2.  References .......................................... 29
   3.3.  Authors' Addresses .................................. 30

   Appendix A - Some Sample Queries .......................... 31
   Appendix B - Some sample responses ........................ 31
   Appendix C - Sample responses to system commands .......... 33
   Appendix D - Sample whois++ session ....................... 35
   Appendix E - System messages .............................. 36
   Appendix F - The WHOIS++ BNF Grammar ...................... 38
   Appendix G - Description of Regular expressions ........... 40

1.  Part I - WHOIS++ Overview

1.1.  Purpose and Motivation

   The current NIC WHOIS service [HARR85] is used to provide a very
   limited directory service, serving information about a small number
   of Internet users registered with the DDN NIC. Over time the basic
   service has been expanded to serve additional information and similar
   services have also been set up on other hosts.  Unfortunately, these
   additions and extensions have been done in an ad hoc and
   uncoordinated manner.

   The basic WHOIS information model represents each individual record
   as a Rolodex-like collection of text. Each record has a unique
   identifier (or handle), but otherwise is assumed to have little
   structure. The current service allows users to issue searches for
   individual strings within individual records, as well as searches for
   individual record handles using a very simple query-response
   protocol.

   Despite its utility, the current NIC WHOIS service cannot function as
   a general White Pages service for the entire Internet. Given the
   inability of a single server to offer guaranteed response or
   reliability, the huge volume of traffic that a full scale directory
   service will generate and the potentially huge number of users of
   such a service, such a trivial architecture is obviously unsuitable
   for the current Internet's needs for information services.

   This document describes the architecture and protocol for WHOIS++, a
   simple, distributed and extensible information lookup service based
   upon a small set of extensions to the original WHOIS information
   model.  These extensions allow the new service to address the
   community's needs for a simple directory service, yet the extensible
   architecture is expected to also allow it to find application in a
   number of other information service areas.

   Added features include an extension to the trivial WHOIS data model
   and query protocol and a companion extensible, distributed indexing
   service. A number of other options have also been added, like boolean
   operators, more powerful search constraints and search methods, and

   most specificly structured the data to make both the client and the
   server part of the dialogue more stringent and parseable. An optional
   authentication mechanism for protecting all or parts of the
   associated WHOIS++ information database from unauthorized access is
   also briefly described.

   The basic architecture of WHOIS++ allows distributed maintenance of
   the directory contents and the use of the WHOIS++ indexing service
   for locating additional WHOIS++ servers. Although a general overview
   of this service is included for completeness, the indexing extensions
   are described in a separate paper.

1.2.  Basic Information Model

   The WHOIS++ service is centered in a recommendation to structure user
   information around a series of standardized information templates.
   Such templates consist of ordered sets of data elements (or
   attribute-value pairs).

   It is intended that adding such structured templates to a server and
   subsequently identifying and searching them be simple tasks.  The
   creation and use of customized templates should also be possible with
   little effort, although their use should be discouraged where
   appropriate standardized templates exist.

   We also offer methods to allow the user to constrain searches to
   desired attributes or template types, in addition to the existing
   commands for specifying handles or simple strings.

   It is expected that the minimalist approach we have taken will find
   application where the high cost of configuring and operating
   traditional White Pages services can not currently be justified.

   Also note that the architecture makes no assumptions about the search
   and retrieval mechanisms used within individual servers.  Operators
   are free to use dedicated database formats, fast indexing software or
   even provide gateways to other directory services to store and
   retrieve information, if desired.

   The WHOIS++ server simply functions as a known front end, offering a
   simple data model and communicating through a well known port and
   query protocol. The format of both queries and replies has been
   structured to allow the use of client software for generating
   searches and displaying the results. At the same time, some effort
   has been made to keep responses at least to some degree readible by
   humans, to ensure low entry cost and to ease debugging.

   The actual implemention details of an individual WHOIS++ search
   engine are left to the imagination of the implementor and it is hoped
   that the simple, extensible approach taken will encourage
   experimentation and the development of improved search engines.

1.2.1.  Changes to the current WHOIS Model

   The current WHOIS service is based upon an extremely simple data
   model.  The NIC WHOIS database consists of a series of individual
   records, each of which is identified by a single unique identifer
   (the "handle"). Each record contains one or more lines of
   information. Currently, there is no structure or implicit ordering of
   this information, although by implication each record is concerned
   with information about a single user or service.

   We have implemented two basic changes to this model. First, we have
   structured the information within the database as collections of data
   elements, or simple attribute/value pairs. Each individual record
   contains a specified ordered set of these data elements.

   Secondly, we have introduced typing of the database records. In
   effect, each record is based upon one of a specified set of
   templates, each containing a finite and specified number of data
   elements. This allow users to easily limit searches to specific
   collections of information, such as information about users,
   services, abstracts of papers, descriptions of software, and so on.

   As a final extension, we require that each individual WHOIS++
   database on the Internet be assigned a unique handle, analogous to
   the handle associated with each database record.

   The WHOIS++ database structure is shown in Fig. 1.

1.2.2.  Registering WHOIS++ servers

   We propose that individual database handles be registered through the
   Internet Assigned Numbers Authority (the IANA), ensuring their
   uniqueness. This will allow us to specify each WHOIS++ entry on the
   Internet as a unique pair consisting of a server handle and a record
   handle.

   A unique registered handle is preferable to using the host's IP
   address, since it is conceivable that the WHOIS++ server for a
   particular domain may move over time.  If we preserve the unique
   WHOIS++ handle in such cases we have the option of using it for
   resource discovery and networked information retrieval (see [IIIR]
   for a discussion of resource and discovery and support issues).

   There are many ways of guaranteeing uniqueness of server handles; we
   will discuss them in a separate paper.

   We believe that organizing information around a series of such
   templates will make it easier for administrators to gather and
   maintain this information and thus encourage them to make such
   information available.  At the same time, as users become more
   familiar with the data elements available within specific templates
   they will be better able to specify their searches, leading to a more
   useful service.

 ______________________________________________________________________
|                                                                      |
|   +  Single unique WHOIS++ database handle                           |
|                                                                      |
|              _______                 _______                _______  |
|    handle3  |..  .. |      handle6  |..  .. |     handle9  |..  .. | |
|            _______  |              _______  |             _______  | |
|  handle2  |..  .. |      handle5  |..  .. |     handle8  |..  .. |   |
|           _______ |               _______ |              _______ |   |
| handle1  |..  .. |      handle4  |..  .. |     handle7  |..  .. |    |
|          |..  .. |               |..  .. |              |..  .. |    |
|           -------                 -------                -------     |
|      Template                   Template               Template      |
|       Type 1                     Type 2                 Type 3       |
|                                                                      |
|                                                                      |
|                                                                      |
|                                                                      |
|               Fig.1 - Structure of a WHOIS++ database.               |
|                                                                      |
| Notes: - Entire database is identified by a single unique WHOIS      |
|          handle.                                                     |
|        - Each record has a single unique handle and a specific set   |
|          of attributes, determined by the template type used.        |
|        - Each value associated with an attribute can be any ASCII    |
|          string up to a specified length.                            |
|______________________________________________________________________|

1.2.3.  The WHOIS++ Search Selection Mechanism

   The WHOIS++ search mechanism is intended to be extremely simple. A
   search command consists of one or more search terms, with an optional
   set of global constraints (specifiers that modify or control a
   search).

   Search terms allow the user to specify template type, attribute,
   value or handle that any record returns must satisfy. Each search
   term can have an optional set of local constraints that apply to only
   that term.

   A WHOIS++ database may be seen as a single rolodex-like collection of
   typed records.  Each term specifies a further constraint that the
   selected set of output records must satisfy. Each term may thus be
   thought of as performing a subtractive selection, in the sense that
   any record that does not fulfil the term is discarded from the result
   set.  Boolean searches are possible by the use of AND, OR, NOT and
   parenthesis.

1.2.4.  The WHOIS++ Architecture

   The WHOIS++ directory service has an architecture which is separated
   into two components; the base level server, which is described in
   this paper, and a indexing server. A single physical server can act
   as both a base level server and an indexing server.

   A base level server is one which contains only filled templates. An
   indexing server is one which contains forward knowledge (q.v.) and
   pointers to other indexing servers or base level servers.

1.3.  Indexing in WHOIS++

   Indexing in WHOIS++ is used to tie together many base level servers
   and index servers into a unified directory service.

   Each base level server and index server which wishes to participate
   in the unified directory service must generate "forward knowledge"
   for the entries it contains. One type of forward knowledge is the
   "centroid".

   An example of a centroid is as follows: if a whois++ server contained
   exactly three records, as follows:

        Record 1                        Record 2
        Template: Person                Template: Person
        First-Name: John                First-Name: Joe
        Last-Name: Smith                Last-Name: Smith
        Favourite-Drink: Labatt Beer    Favourite-Drink: Molson Beer

        Record 3
        Template: Domain
        Domain-Name: foo.edu
        Contact-Name: Mike Foobar

        the centroid for this server would be

        Template:       Person
        First-Name:     Joe
                        John
        Last-Name:      Smith
        Favourite-Drink:Beer
                        Labatt
                        Molson

        Template:       Domain
        Domain-Name:    foo.edu
        Contact-Name:   Mike
                        Foobar

   An index server would then collect this centroid for this server as
   forward knowledge.

   Index servers can collect forward knowledge for any servers it
   wishes.  In effect, all of the servers that the index server knows
   about can be searched with a single query to the index server; the
   index server holds the forward knowledge along with pointers to the
   servers it indexes, and can refer the query to servers which might
   hold information which satisfies the query.

   Implementors of this protocol are strongly encouraged to incorporate
   centroid generation abilities into their servers.

-------------------------------------------------------------------

                              ____             ____
top level                    |    |           |    |
whois index                  |    |           |    |
servers                       ----             ----

                        ____                ____
first level            |    |              |    |
whois index            |    |              |    |
servers                 ----                ----

                    ____                ____                ____
individual         |    |              |    |              |    |
whois servers      |    |              |    |              |    |
                    ----                ----                ----

                 Fig. 2 - Indexing system architecture.

-------------------------------------------------------------------

1.4.  Getting Help

   Another extension to the basic WHOIS service is the requirement that
   all servers support at least a minimal set of help commands, allowing
   users to find out information about both the individual server and
   the entire WHOIS++ service itself. This is done in the context of the
   new extended information model by defining two specific template
   formats and requiring each server to offer at least one example of
   each record using these formats. The operator of each WHOIS service
   is therefor expected to have, as a minimum, a single example of
   SERVICES and HELP records, which can be accessed through appropriate
   commands.

1.4.1.  Minimum HELP Required

     Executing the command:

             DESCRIBE

     gives a brief information about the WHOIS++ server.

     Executing the command:

             HELP

     gives a brief description of the WHOIS++ service itself.

     The text of both required helped records should contain pointers to
     additional help subjects that are available.

     Executing the command:

             HELP <searchstring>

     may give information on any topic.

1.5.  Options and Constraints

   The WHOIS++ service is based upon a minimal core set of commands and
   controlling constraints. A small set of additional optional commands
   and constraints can be supported. These would allow users to perform
   such tasks as provide security options, modify the information
   contents of a server or add multilingual support. The required set of
   WHOIS++ commands are summarized in section 2.2.  WHOIS++ constraints
   are described in section 2.3. Optional constraints are described in
   section 2.3.2.

1.6.  Formatting Responses

   The output returned by a WHOIS++ server is structured to allow
   machine parsing and automated handling. Of particular interest in the
   ability to return summary information about a search (without having
   to return the entire results).

   All output of searches will be returned in one of five output
   formats, which will be one of FULL, ABRIDGED, HANDLE, SUMMARY or
   SERVER-TO-ASK.  Note that a conforming server is only required to
   support the first four formats.

   When available, SERVER-TO-ASK format is used to indicate that a
   search cannot be completed but that one or more alternative WHOIS++
   servers may be able to perform the search.

   Details of each output format are specified in section 2.4.

1.7.  Reporting Warnings and Errors

   The formatted response of WHOIS++ commands allows the encoding of
   warning or error messages to simplify parsing and machine handling.
   The syntax of output formats are described in detail in section 2.4,
   and details of WHOIS++ warnings and error conditions are given in
   Appendix E.

   All system messages are numerical, but can be tagged with text. It is
   the clients decision if the text is presented to the user.

1.8.  Privacy and Security Issues

   The basic WHOIS++ service was conceived as a simple, unauthenticated
   information lookup service, but there are occasions when
   authentication mechanisms are required. To handle such cases, an
   optional mechanism is provided for authenticating each WHOIS++
   transaction.

   The current identified authentication mechanism is PASSWORD, which
   uses simple password authentication. Any other scheme name used must
   begin with the characters "X-" and should thus be regarded as
   experimental and non-standard.

   Note that the WHOIS++ authentication mechanism does not dictate the
   actual authentication scheme used, it merely provides a framework for
   indicating that a particular transaction is to be authenticated, and
   the appropriate mechanisms to use. This mechanism is extensible and
   individual implementors are free to add additional mechanisms.

   This document includes a very simple authentication scheme where a
   combination of username and password is sent together with the search
   string so the server can verify that the user have access to the
   information. Note that this is NOT by any means a method recommended
   to secure the data itself because both password and information are
   tranferred unencrypted over the network.

   Given the unauthenticated nature that default services like white
   pages services are, it is easy to either forget the implications of
   this and just show all data to the public Internet, or think that
   Internet is so dangerous that information is hidden from the Internet
   so the whole idea of a global white pages service is lost.  Therefore
   the type of authentication scheme selected and the public nature of
   the Internet environment must still be taken into consideration when
   assessing the security and authentication of the information served.

   A more detailed exposition on security is outside the scope of this
   document.

2.  Part II - WHOIS++ Implementation

2.1.  The WHOIS++ interaction model

   A WHOIS++ server will normally listen for a TCP connections on the
   allocated WHOIS++ port (although a WHOIS++ server can be accessed
   over any TCP connection). Once a connection is established, the
   server issues a banner message, and listens for input. The command
   specified in this input is processed and the results returned
   including an ending system message. If the optional HOLD constraint
   has not been specified the connection is then terminated.

   If the server supports the optional HOLD constraint, and this
   constraint is specified as part of any command, the server continues
   to listen on the connection for another line of input.  This cycle
   continues as long as the sender continues to append the required HOLD
   constraint to each subsequent command.

   At the same time, each server is permitted to set an optional timeout
   value (which should be indicated in the response to the CONSTRAINTS
   command). If set, the server is free to terminate an idle connection
   at any time after this delay has passed with no input from the
   client. If the server terminates the connection due to timeout, it
   will be indicated by the system message. The timeout value is not
   changeable by the client.

2.2.  The WHOIS++ Command set

   There are two types of WHOIS++ commands - system commands and the
   WHOIS++ search command.

   The WHOIS++ command set consists of a core set of required systems
   commands, a single required search command and an set of optional
   system commands which support features that are not required by all
   servers. The set of required WHOIS++ system commands are listed in
   Table I. Details of the allowable search terms for the search command
   are included in Table II.

   Each WHOIS++ command also allows the use of one or more controlling
   constraints, when selected can be used to override defaults or
   otherwise modify server behavior. There is a core set of constraints
   that must be supported by all conforming servers. These include
   SEARCH (which controls the type of search performed), FORMAT (which
   determines the output format used) and MAXHITS (which determines the
   maximum number of matches that a search can return).

   These required constraints are summarized in Table III.

   An additional set of optional constraints are used to provide support
   for different character sets, indicate the need and type of
   authentication to perform on a transaction, and permit multiple
   transactions during a single communications session. These optional
   constraints are listed in Table IV.

   It is possible, using the required COMMANDS and CONSTRAINTS system
   commands, to query any WHOIS++ server for its list of supported
   commands and constraints.

2.2.1.  System Commands

   System commands are commands to the server for information or to
   control its operation. These include commands to list the template
   types available from individual servers, to obtain a single blank
   template of any available type, and commands to obtain the list of
   valid commands and constraints supported on a server.

   There are also commands to obtain the current version of the WHOIS++
   protocol supported, to access a simple help subsystem, to obtain a
   brief description of the service (which is intended, among other
   things, to support the automated registration of the service by
   yellow pages directory services). All of these commands are required
   from a conforming WHOIS++ server.

------------------------------------------------------------------------

Short  Long Form                               Functionality
-----  ---------                               -------------
       COMMANDS        [ ':' HOLD ]          list valid WHOIS++ commands
                                             supported by this server

       CONSTRAINTS     [ ':' HOLD ]          List valid constraints
                                             supported by this server

       DESCRIBE        [ ':' HOLD ]          Describe this server,
                                             formating the response
                                             using a standard
                                             "Services" template

 '?'   HELP [<string>  [':' <cnstrnts>]]     System help, using a "Help"
                                             template

       LIST            [':' <cnstrnts>]      List templates supported
                                             by this system

       POLLED-BY       [ ':' HOLD ]          List indexing servers
                                             that are know to track
                                             this server

       POLLED-FOR      [ ':' HOLD ]          List information about
                                             what this server is
                                             tracking for

       SHOW <string>   [':' <cnstrnts>]      Show contents of templates
                                             specified

       VERSION         [ ':' HOLD ]          return current version of
                                             the protocol supported.

              Table I - Required WHOIS++ SYSTEM commands.

------------------------------------------------------------------------

   Below follows a descriptions for each command. Examples of responses
   to each command is in Appendix C.

2.2.1.1.  The COMMANDS command

   The COMMANDS command returns a list of commands that the server
   supports. The response is formatted as a FULL response.

2.2.1.2.  The CONSTRAINTS command

   The CONSTRAINTS command returns a list of constraints and the values
   of those that the server supports. The response is formatted as a
   FULL response, where every constraint is represented as a separate
   record. The template name for these records is CONSTRAINT.  No
   attention is paid to handles. Each record has, as a minimum, the
   following two fields:

     - "Constraint", which contains the attribute name described -
       "Default", which shows the default value for this constraint.

   If the client is permitted to change the value of the constraint,
   there is also:

     - "Range" field, which contains a list of values that this
       server supports, as a comma separated list; Or, if the range
       is numerical, as a pair of numbers separated with a hyphen.

2.2.1.3.  The DESCRIBE command

   The DESCRIBE command gives a brief description about the server in a
   "Services" template. The result is formatted as a FULL response.

2.2.1.4.  The HELP command

   The HELP command takes an optional argument as subject to get help
   for.

2.2.1.5.  The LIST command

   The LIST command returns the name of the templates available on the
   server. The answer is formatted FULL format response.

2.2.1.6.  The POLLED-BY command

   The POLLED-BY command returns a list of servers and the templates and
   attribute names that those server polled as centroids from this
   server. The format is in FULL format with two attributes, Template
   and Field. Each of these is a list of names of the templates or
   fields polled.  An empty result means either that the server is not
   polled by anyone, or that it doesn't support indexing.

2.2.1.7.  The POLLED-FOR command

   The POLLED-FOR command returns a list of servers that this server has
   polled, and the template and attribute names for each of those.  The
   answer is in FULL format with two attributes, Template and Field.  An
   empty result means either that the server is not polling anyone, or
   that it doesn't support indexing.

2.2.1.8.  The SHOW command

   The SHOW command takes a template name as argument and returns
   information about a specific template, formatted as a FULL response.
   The answer is formatted as a blank template with the requested name.

2.2.1.9.  The VERSION command

   The output format is a FULL response containg a record with template
   name VERSION. The record must have attribute name "Version", which
   value is "1.0" for this version of the protocol.  The record may also
   have the additional fields "Program-Name" and "Program-Version" which
   gives information about the server implementation if the server so
   desires.

2.2.2.  The Search Command

   A search command consists of one or more search terms, which might
   each have local constraints, followed by an optional colon with a set
   of global search constraints.

   Each attribute value in the WHOIS++ database is divided into one or
   more words separated by whitespace. Each search term operates on
   every word in the attribute value.

   Two or more search terms may be combined with boolean operators AND,
   OR or NOT (other than the implied AND between terms). The operator
   AND has higher precedence than the operator OR, but this can be
   changed by the use of parentheses.

   Search constraints that apply to every search term are specified as
   global constraints. Local constraints override global constraints for
   the search term they are bound to. The search terms and the global
   constraints are separated with a colon (':'). Additional global
   constraints are appended to the end of the search command delimited
   with a semicolon ';'.

   If different search constraints can not be fulfilled, or the
   combination of different search constraints is uncombinable, the
   server may choose to ignore some constraints, but still do the search

   and return some records.

   The set of required constraints are summarized in Table III. The set
   of optional constraints are summarized in Table IV.

   As an option, the server may accept specifications for attributes for
   either inclusion or exclusion from a reply. Thus, users could specify
   -only- those attributes to return, or specific attributes to filter
   out, thus creating custom views.

2.2.2.1.  Format of a Search Term

   Each search term consists of one of the following:

     1) A search string, followed by an optional semicolon and set of
        semicolon-separated local constraints.

     2) A search term specifier (as listed in Table II), followed by a
        '=', followed by a search string, an optional semicolon and a
        set of semicolon-separate local constraints.

     3) An abbreviated search term specifier, followed by a search
        string, followed by an optional semicolon and set of
        semicolon-separated local constraints.

     4) A combination of attribute name, followed by '=', followed by
        a search string, followed by an optional semicolon and set of
        semicolon-separate local constraints.

   If no term identifier is provided, then the search will be applied to
   attribute values only. This corresponds to an identifier of VALUE.

   If a SEARCH-ALL specifier is used then the search will be applied to
   all template names, handles, attribute names and attribute values.

   When the user specifies the search term using the form:

             "<attribute_name> = <value>"

   this is considered to be an ATTRIBUTE-VALUE search.

   For discussion of the system reply format, and selecting the
   appropriate reply format, see section 2.4.

     -------------------------------------------------------------------

     Valid specifiers:
     -----------------

      Name                                  Functionality
      ----                                  -------------

      ATTRIBUTE-VALUE [ ';' <constrnt>]*    allows combining
                                            attribute and value
                                            specifiers in one term.
      HANDLE          [ ';' <constrnt>]*    Confine search to handles.
      SEARCH-ALL      [ ';' <constrnt>]*    Search everything.
      TEMPLATE        [ ';' <constrnt>]*    Confine search to
                                            template names.
      VALUE           [ ';' <constrnt>]*    Confine search to attribute
                                            values. This is the default.

     (Note: The name HANDLE can be replaced with the shortname '!')

     Acceptable forms of a search specifier:
     ---------------------------------------

     1) <searchstring>  [';' <constraint>]*

     2) <specifier> = <searchstring> [';' <constraint>]*

     3) <shortspecifier> <searchstring>  [';' <constraint>]*

     4) <attribute_name> = <searchstring>  [';' <constraint>]*

     (Note: A <constraint> is a name of a valid local constraint.)

            Table II - Valid search command term specifiers.

     -------------------------------------------------------------------

2.2.2.2.  Format of a Search String

   Special characters that need to be quoted are preceeded by a
   backslash, '\'.

   Special characters are space ' ', tab, equal sign '=', comma ',',
   colon ':', backslash '\', semicolon ';', asterisk '*', period '.',
   parenthesis '()', square brackets '[]', dollar sign '$' and
   circumflex '^'.

   If the search term is given in some other character set than ISO-
   8859-1, it must be specified by the constraint INCHARSET.

2.3.  WHOIS++ Constraints

   Constraints are intended to be hints or recommendations to the server
   about how to process a command. They may also be used to override
   default behaviour, such as requesting that a server not drop the
   connection after performing a command.

   Thus, a user might specify a search constraint as "SEARCH=exact",
   which means that the search engine is to perform an exact match
   search. It might also specify "LANGUAGE=Fr", which implies that the
   server should use French in fuzzy matches. It might also be able to
   issue system messages in French.

   In general, contraints take the form "<constraintname>=<value>", with
   <value> being one of a specified set of valid values. The notable
   exception is "HOLD", which takes no argument.

   All constraints can be used as a global constraint, but only a few
   can be used as local. See tables IV and V for information of which
   constraints can be local.

   The CONSTRAINTS system command is used to list the search constraints
   supported by an individual server.

   If a server cannot satisfy the specified constraint there will be a
   mechanism for informing the user in the reply, using system messages.
   In such cases, the search is still performed, with the the server
   ignoring unsupported constraints.

2.3.1.  Required Constraints

   The following CONSTRAINTS must be supported in all conforming WHOIS++
   servers.

     ------------------------------------------------------------------

      Format                                           LOCAL/GLOBAL
      ------                                           -------------

     SEARCH=   {exact | lstring }                      LOCAL/GLOBAL

     FORMAT=   {full | abridged | handle | summary }   GLOBAL

     MAXHITS=  { 1-<max-allowed> }                     GLOBAL

     Table III - Required WHOIS++ constraints.

     ------------------------------------------------------------------

2.3.2.  Optional CONSTRAINTS

   The following CONSTRAINTS and constraint values are not required of a
   conforming WHOIS++ server, but may be supported. If supported, their
   names and supported values must be returned in the response to the
   CONSTRAINTS command.

  ---------------------------------------------------------------------

   Format                                                  LOCAL/GLOBAL
   ------                                                  -------------

  SEARCH=       { regex | fuzzy | substring | <X-format> } LOCAL/GLOBAL

  CASE=         { ignore | consider }                      LOCAL/GLOBAL

  FORMAT=       { server-to-ask | <X-format> }             GLOBAL

  MAXFULL=      { 1-<max-allowed> }                        GLOBAL

  AUTHENTICATE= password                                   GLOBAL

  NAME=         <string>                                   GLOBAL

  PASSWORD=     <string>                                   GLOBAL

  INCHARSET=    { us-ascii | iso-8859-* }                  GLOBAL

  LANGUAGE=     <As defined in ISO 639:1988>               GLOBAL

  HOLD                                                     GLOBAL

  IGNORE=       {attributelist}                            GLOBAL

  INCLUDE=      {attributelist}                            GLOBAL

                Table IV - Optional WHOIS++ constraints.

  ----------------------------------------------------------------------

2.3.2.1.  The SEARCH Constraint

   The SEARCH constraint is used for specifying the method that is to be
   used for the search. The default method is "exact". Following is a
   definition of each search method.

   exact           The search will succeed for a word that exactly
                   matches the search string.

   substring       The search will succeed for a word that matches
                   a part of a word.

   regex           The search will succeed for a word when a regular
                   expression matches the searched data. Regular
                   expression is built up by using constructions of
                   '*', '.', '^', '$', and '[]'. For use of
                   regular expressions see Appendix G.

   fuzzy           The search will succeed for words that matches the
                   search string by using an algorithm designed to catch
                   closely related names with different spelling, e.g.
                   names with the same pronounciation.  The server
                   chooses which algorithm to use, but it may vary
                   depending on template name, attribute name and
                   language used (see Constraint Language above).

   lstring         The search will succed for words that begins
                   with the search string.

2.3.2.2.  The FORMAT Constraint

   The FORMAT constraint describes what format the result will be in.
   Default format is FULL. For a description of each format, see Server
   Response Modes below.

2.3.2.3.  The MAXFULL Constraint

   The MAXFULL constraint sets the limit of the number of matching
   records the server allows before it enforces SUMMARY responses.  The
   client may attempt to override this value by specifying another value
   to that constraint. Example: If, for privacy reasons, the server will
   return the response in SUMMARY format if the number of hits exceeds
   2, the MAXFULL constraint is set to 2 by the server.

   Regardless of what format the client did or did not ask for, the
   server will change the response format to SUMMARY when the number of
   matching records equals or exceeds this value.

2.3.2.4.  The MAXHITS Constraint

   The MAXHITS constraint sets the maximum number of records the client
   can get in a search respone.

2.3.2.5.  The CASE Constraint

   The CASE constraint defines if the search should be done case
   sensistive or not. Default value is to have case ignored.

2.3.2.6.  The AUTHENTICATE Constraint

   The AUTHENTICATE constraint describes which authentication method to
   use when executing the search. By using a specific authentication
   method, some other constraints might be needed which is specified by
   the authentication method.

   The only authentication method described in this document is
   "password", if used, also the two other constraints "name" and
   "password" need to be set.

2.3.2.7.  The NAME Constraint

   The NAME constraint is only used together with some authentication
   method named by the constraint "authenticate". The only use described
   in this document is by sending a username as a string of characters
   which together with the string given as an argument to the "password"
   constraint is sent to the server. The server can use that pair of
   strings to do a simple authentication check, similar to the UNIX
   login program.

2.3.2.8.  The PASSWORD Constraint

   The PASSWORD constraint is only used together with some
   authentication method named by the constraint "authenticate". The
   only use described in this document is by sending a password as a
   string of characters which together with the string given as an
   argument to the "name" constraint is sent to the server. The server
   can use that pair of strings to do a simple authentication check,
   similar tothe UNIX login program.

2.3.2.9.  The LANGUAGE Constraint

   The LANGUAGE constraints can be used as an extra information to the
   fuzzy matching search method, and it might also be used to tell the
   server to give the system responses in another language, although
   this ability should be handled by the client. The language code
   defined in RFC 1766 [ALVE95] can be used as a value for the language

   constraint.  In these, the case of the letters are insignigicant.

2.3.2.10.  The INCHARSET Constraint

   The INCHARSET constraint tells the server in which character set the
   search string itself is given in. The default character set is ISO-
   8859-1.

2.3.2.11.  The IGNORE Constraint

   The IGNORE constraint specifies which attributes to NOT include in
   the result. All other attributes will be included (as if named
   explicitly by the "include" constraint).

   If an attribute is named both with the "include" and "ignore"
   constraint, the attribute is to be included in the result, but the
   system message must be "% 205 Requested constraint not fulfilled".

2.3.2.12.  The INCLUDE Constraint

   The INCLUDE constraint specifies which attributes to include in the
   result. All other attributes will be excluded (as if named explicitly
   by the "ignore" constraint).

   If an attribute is named both with the "include" and "ignore"
   constraint, the attribute is to be included in the result, but the
   system message must be "% 205 Requested constraint not fulfilled".

2.4.  Server Response Modes

   There are currently a total of five different response modes possible
   for WHOIS++ servers. These are FULL, ABRIDGED, HANDLE, SUMMARY and
   SERVER-TO-ASK. The syntax of each output format is specified in more
   detail in the following section.

     1) A FULL format response provides the complete contents of a
        template matching the specified query, including the template
        type, the server handle and an optional record handle.

     2) An ABRIDGED format response provides a brief summary, including
        (as a minimum) the server handle, the corresponding record handle
        and relevant information for that template.

     3) A HANDLE format response returns a line with information about
        the server handle and record handle for a record that matched
        the specified query.

     4) A SUMMARY response provides only a brief summary of information
        the number of matches and the list of template types in which the
        matches occured.

     5) A SERVER-TO-ASK response only returns pointers to other index
        servers which might possibly be able to answer the specified
        query.

   The server may respond with a null answer and may also respond with a
   null answer together with a correct system message to indicate that
   the query was too complex.

2.4.1.  Default Responses

   By default, a WHOIS++ server will provide FULL responses. This may be
   changed by the client with the use of the global constraint "format".

   The server is allowed to provide response in SUMMARY format if the
   number of hits exceeds the value of the global constraint "maxfull".

   The server will not respond with more matches than the value
   specified with the global constraint "maxhits"; Not in any response
   format. If the number of matches exceeds this value, the server will
   issues the system message 110 (maxhits value exceeded), but will
   still show the responses, up to the number of the "maxhits"
   constraint value.  This mechanism will allow the server to hide the
   number of possible matches to a search command.

   The server response modes are summarized in Table V.

2.4.2.  Format of Responses

   Each response consists of a numerical system generated message, which
   can be tagged with text, followed by an optional formatted response
   message, followed by a second system generated messages.

   That is:

        '%' <system messages> <nl>

        [ <formatted response> ]

        '%' <system messages> <nl>

   If there are no matches to a query, the system is not required to
   generate any output as a formatted response, although it must still
   generate system messages.

   For information about the format for system messages, see Appendix E.

2.4.3.  Syntax of a Formatted Response

   All formatted responses except for the HANDLE response, consists of a
   response-specific START line, followed by an optional response-
   specific data section, followed by a TERMINATION line.  The HANDLE
   response is different in that it only consists of a START line.  It
   is permissible to insert any number of lines consisting solely of
   newlines within a formatted response to improve readibility.

   Each line shall be limited to no more than 81 characters, including
   the terminating newline.  If a line (including the required leading
   single space) would exceed 81 characters, it is to be broken into
   lines of no more than 81 characters, with each continuation line
   beginning with a "+" character in the first column instead of the
   leading character.

   If an attribute value in a data section includes a line break, the
   line break must be replaced by a CR/LF pair and the following line
   begin with a "-" character in the first column, instead of the
   leading character. The attribute name is not repeated on consecutive
   lines.

   A TERMINATION line consists of a line with a '#' in the first column,
   followed by one white space character (SPACE or TAB), followed by the
   keyword END, followed by zero or more characters, followed by a
   newline.

   A response-specific section will be one of the following:

       1) FULL Format Response
       2) ABRIDGED Format Response
       3) HANDLE Format Response
       4) SUMMARY Format Response
       5) SERVER-TO-ASK Format Response

        The details of each are specified in the following sections:

2.4.3.1.  A FULL format response

   A FULL format response consists of a series of responses, each
   consisting of a START line, followed by the complete template
   information for the matching record and a TERMINATION line.

   Each START line consists of a '#' in the first column, followed by
   one white space character, the word "FULL", a white space character,
   the name of the corresponding template type, one white space

   character, the server handle, a white space character, an optional
   handle for the record, and a terminating newline.

   The template information for the record will be returned as a series
   of lines consisting of a single space, followed by the corresponding
   line of the record.

   The line of the record shall consist of a single space and the
   attribute name followed by a ':', a single space, the value of that
   attribute, and a newline.

2.4.3.2.  ABRIDGED Format Response

   Each ABRIDGED format response consists of a START line, a single line
   excerpt of the template information from each matching record and a
   TERMINATION line. The excerpt information shall include information
   that is relevant to the template type.

   The START line consists of a '#' in the first column, followed by one
   white space character, the word "ABRIDGED", a white space character,
   the name of the corresponding template type, a white space character,
   the server handle, a white space character, the handle for the
   record, and a terminating newline.

   The abridged template information will be returned as a line,
   consisting of a single space, followed by the abridged line of the
   record and a newline pair.

2.4.3.3.  HANDLE Format Response

   A HANDLE response consists of a single START line, which shall start
   with a '#' in the first column, followed by one white space
   character, the word "HANDLE", a white space character, the name of
   the corresponding template, a white space character, the handle for
   the server, a white space character, the handle for that record, and
   a terminating newline.

2.4.3.4.  SUMMARY Format Response

   A SUMMARY format response consists of a single set of responses,
   consisting of a line listing the number of matches to the specified
   query, followed by a list of all template types which satisfied the
   query at least once.

   The START line shall begin with a '#' in the first column, be
   followed by one white space character, the word "SUMMARY", a white
   space character, the handle for the server, and a terminating
   newline.

   All following lines until the TERMINATION line starts with a leading
   space.  The first line shall begin with the string "matches: ", be
   followed by a space and the number of responses to the query and
   terminated by a newline.  The second line shall begin with the string
   "templates: ", be followed by a newline separated list of the name of
   the template types which matched the query.  Each line following the
   first which include the text "templates:" must begin with a '-'
   instead of a space.

2.4.3.5.  SERVER-TO-ASK Response

   A SERVER-TO-ASK response consists of information to the client about
   a server to contact next to resolve a query.  If the server has
   pointers to more than one server, it will present additional SERVER-
   TO-ASK responses.

   The SERVER-TO-ASK response will consist of a START line and a number
   of lines with attribute-value pairs, separated by CRLF. Each line is
   indented with one space. The end of a SERVER-TO-ASK response is
   indicated with a TERMINATION line.

   Each START line consists of a '#' in the first column, followed by
   one white space character, the word "SERVER-TO-ASK", a white space
   character, the handle of the server and a terminating newline.

   1. "Server-Handle" - The server handle of the server pointed at.
      (req.)
   2. "Host-Name" - A cached host named for the server pointed at. (opt.)
   3. "Host-Port" - A cached port number for the server pointed at.
      (opt.)

   Other attributes may be present, depending on the index server.

2.4.4.  System Generated Messages

   All system generated messages must begin with a '%' as the first
   character, a space as the second one, followed by a three digit
   number, a space and an optional text message. The total length of the
   line must be no more than 81 characters long, including the
   terminating CR LF pair. There is no limit to the number of system
   messages that may be generated.

   The format for multiline replies requires that every line, except the
   last, begin with "%", followed by space, the reply code, a hyphen,
   and an optional text.  The last line will begin with "%", followed by
   space, the reply code, a space and some optional text.

   System generated messages displayed before or after the formatted
   response section are expected to refer to operation of the system or
   refer to the entire query. System generated messages within the
   output of an individual record during a FULL reponse are expected to
   refer to that record only, and could (for example) be used to
   indicate problems with that record of the response. See Appendix E
   for a description of system messages.

2.5.  Compatibility with Older WHOIS Servers

   Note that this format, although potentially more verbose, is still in
   a human readible form. Responses from older systems that do not
   follow this format are still conformant, since their responses would
   be interpreted as being equivalent to optional text messages, without
   a formatted response.  Clients written to this specification would
   display the responses as a advisory text message, where it would
   still be readible by the user.

3.  Miscellaneous

3.1.  Acknowledgements

   The WHOIS++ effort began as an intensive brainstorming session at the
   24th IETF, in Boston Massachusetts.  Present at the birth, and
   contributing ideas through this early phase, were (alphabetically)
   Peter Deutsch, Alan Emtage, Jim Fullton, Joan Gargano, Brad
   Passwaters, Simon Spero, and Chris Weider. Others who have since
   helped shape this document with feedback and suggestions include
   Roxana Bradescu, Patrik Faltstrom, Kevin Gamiel, Dan Kegel, Michael
   Mealling, Mark Prior and Rickard Schoultz.

3.2  References

   [ALVE95]        Alvestrand H., "Tags for the Identification of
                   Languages", RFC 1766, UNINETT, March 1995.

   [HARR85]        Harrenstein K., Stahl M., and E. Feinler,
                   "NICNAME/WHOIS", RFC 954, SRI, October 1985.

   [IIIR]          Weider C., and P. Deutsch, "A Vision of an
                   Integrated Internet Information Service", RFC 1727
                   Bunyip Information Systems, Inc., December 1994.

   [POST82]        Postel J., "Simple Mail Transfer Protocol", STD 10,
                   RFC 821, USC/Information Sciences Institute,
                   August 1982.

3.3.  Authors' Addresses

   Peter Deutsch
   BUNYIP INFORMATION SYSTEMS, Inc.
   310 St-Catherine St West,
   Suite 202,
   Montreal, Quebec H2X 2A1
   CANADA

   EMail: peterd@bunyip.com

   Rickard Schoultz
   KTHNOC, SUNET/NORDUnet/Ebone Operations Centre
   100 44 STOCKHOLM
   SWEDEN

   EMail: schoultz@sunet.se

   Patrik Faltstrom
   BUNYIP INFORMATION SYSTEMS, Inc.
   310 St-Catherine St West,
   Suite 202,
   Montreal, Quebec H2X 2A1
   CANADA

   EMail: paf@bunyip.com

   Chris Weider
   BUNYIP INFORMATION SYSTEMS, Inc.
   2001 S. Huron Parkway, #12
   Ann Arbor, MI 48104
   USA

   EMail: clw@bunyip.com

Appendix A - Some Sample Queries

       author=chris and template=user

   The result will consist of all records where attribute "author"
   matches "chris" with case ignored. Only USER templates will be
   searched. An example of a matching record is "Author=Chris Weider".
   This is the typical case of search.

       schoultz and rick;search=lstring

   The result will consist of all records which have one attribute value
   matching "schoultz" exactly and one having "rick" as leading
   substring, both with case ignored. One example is "Name=Rickard
   choultz".

       value=phone;search=substring

   The result will consist of all records which have attribute values
   matching *phone*, for example the record "Name=Acme telephone inc.",
   but will not match the attribute name "phone". (Since "value" term
   specifier is the default, the search term could be "phone" as well as
   "value=phone".)

       search-all=Peter ; search=substring;case=consider

   The result will consist of all records which have attribute names,
   template names or attribute values matching "Peter" with respect to
   case. One example is "Friend-Of-Peter: Yes".

      ucdavis;search=substring and (gargano or joan):include=name,email

   This search command will find records which have records containing
   the words "gargano" or "joan" somewhere in the record, and has the
   word "ucdavis" somewhere in a word. The result will only show the
   "name" and "email" fields.

Appendix B - Some sample responses

      1) FULL format responses:

      # FULL USER SERVERHANDLE1 PD45
       Name: Peter Deutsch
       email: peterd@bunyip.com
      # END
      # FULL USER SERVERHANDLE1 AE1
       Name: Alan Emtage
       email: bajan@bunyip.com

      # END
      # FULL USER SERVERHANDLE1 NW1
       Name: Nick West
       Favourite-Bicycle-Forward-Wheel-Brand: New Bicy
      +cles Acme Inc.
       email: nick@bicycle.acme.com
       My-favourite-song: Happy birthday to you!
      -Happy birthday to you!
      -Happy birthday dear Nick!
      -Happy birthday to you.
      # END
      # FULL SERVICES SERVERHANDLE1 WWW1
       Type: World Wide Web
       Location: the world
      # END

                          --------------------

      2) An ABRIDGED format response:

      # ABRIDGED USER SERVERHANDLE1 PD45
       Peter Deutsch             peterd@bunyip.com
      # END
      # ABRIDGED USER SERVERHANDLE1 AE1
       Alan Emtage               bajan@bunyip.com
      # END
      # ABRIDGED USER SERVERHANDLE1 WWW1
       World Wide Web            the world
      # END

                          --------------------

      3) HANDLE format responses:

      # HANDLE USER SERVERHANDLE1 PD45
      # HANDLE USER SERVERHANDLE1 AE1
      # HANDLE SERVICES SERVERHANDLE1 WWW1

                          --------------------

      4) A SUMMARY HANDLE format response:

      # SUMMARY SERVERHANDLE1

        Matches:      175
        Templates:    User
      -               Services
      -               Abstracts
      # END

Appendix C - Sample responses to system commands

   C.1 Response to the LIST command

      # FULL LIST SERVERHANDLE1
       Templates: USER
      -SERVICES
      -HELP
      # END

   C.2 Response to the SHOW command

      This example shows the result after issuing "show user":

      # FULL USER SERVERHANDLE1
        Name:
        Email:
        Work-Phone:
        Organization-Name:
        City:
        Country:
      # END

   C.3 Response to the POLLED-BY command

      # FULL POLLED-BY SERVERHANDLE1
       Server-handle: serverhandle2
       Cached-Host-Name: sunic.sunet.se
       Cached-Host-Port: 7070
       Template: USER
       Field: ALL
      # END
      # FULL POLLED-BY SERVERHANDLE1
       Server-handle: serverhandle3
       Cached-Host-Name: kth.se
       Cached-Host-Port: 7070
       Template: ALL

       Field: Name,Email
      # END

   C.4 Response to the POLLED-FOR command

      # FULL POLLED-FOR SERVERHANDLE1
       Server-Handle: serverhandle5
       Template: ALL
       Field: Name,Address,Job-Title,Organization-Name,
      +Organization-Address,Organization-Name
      # END
      # FULL POLLED-FOR SERVERHANDLE1
       Server-Handle: serverhandle4
       Template: USER
       Field: ALL
      # END

   C.5 Response to the VERSION command

      # FULL VERSION BUNYIP.COM
       Version: 1.0
       Program-Name: kth-whoisd
       Program-Version: 2.0
      # END

   C.6 Response to the CONSTRAINTS command

      # FULL CONSTRAINT COMEDIA.SE
       Constraint: format
       Default: full
       Range: full,abridged,summary,handle
      # END
      # FULL CONSTRAINT COMEDIA.SE
       Constraint: maxhits
       Default: 200
       Range: 1-1000
      # END
      # FULL CONSTRAINT COMEDIA.SE
       Constraint: search
       Default: exact
       Range: exact,substring,lstring
      # END
      # FULL CONSTRAINT COMEDIA.SE
       Constraint: maxfull
       Default: 20

      # END

   C.3 Response to the COMMANDS command

      # FULL COMMANDS SERVERHANDLE1
       Commands: commands
      -constraints
      -describe
      -help
      -list
      -polled-by
      -polled-for
      -show
      -version
      # END

Appendix D - Sample whois++ session

   Below is an example of a session between a client and a server. The
   angle brackets to the left is not part of the communication, but is
   just put there to denonte the direction of the communication between
   the server or the client. Text appended to '>' means messages from
   the server and '<' from the client.

     Client connects to the server

     >% 220-Welcome to
     >% 220-the whois++ server
     >% 220 at ACME inc.
     <name=Nick:hold
     >% 200 Command okay
     >
     ># FULL USER ACME.COM NW1
     > name: Nick West
     > email: nick@acme.com
     ># END
     ># SERVER-TO-ASK ACME.COM
     > Server-Handle: SUNETSE01
     > Host-Name: whois.sunet.se
     > Host-Port: 7070
     ># END
     ># SERVER-TO-ASK ACME.COM
     > Server-Handle: KTHSE01
     ># END
     >% 226 Tranfer complete
     <version
     >% 200 Command okay
     ># FULL VERSION ACME.COM

     > Version: 1.0
     ># END
     >% 226 Tranfer complete
     >% 203 Bye
     Server closes the connection

   In the example above, the client connected to a whois++ server and
   queried for all records where the attribute "name" equals "Nick", and
   asked the server not to close the connection after the response by
   using the global constraint "HOLD".

   The server responds with one record and a pointer to two other
   servers that either holds records or pointers to other servers.

   The client continues with asking for the servers version number
   without using the HOLD constraint.  After responding with protocol
   version, the server closes the connection.

   Note that each response from the server begins system message 200
   (Command OK), and ends with system message 226 (Transfer Complete).

Appendix E - System messages

   A system message begins with a '%', followed by a space and a three
   digit number, a space, and an optional text message. The line message
   must be no more than 81 characters long, including the terminating CR
   LF pair. There is no limit to the number of system messages that may
   be generated.

   A multiline system message have a hyphen instead of a space in column
   6, immediately after the numeric response code in all lines, except
   the last one, where the space is used.

     Example 1

     % 200 Command okay

     Example 2

     % 220-Welcome to
     % 220-the whois++ server
     % 220 at ACME inc.

   The client is not expected to parse the text part of the response
   message except when receiving reply 600, in which case the text part
   is the name of a character set that will be used by the server in the
   rest of the response. The valid values for characters sets is
   specified in the "characterset" list in the BNF listing in Appendix

   F.

   The theory of reply codes is described in Appendix E in STD 10, RFC
   821 [POST82].

------------------------------------------------------------------------

List of system response codes
------------------------------

110 Too many hits                         The number of matches exceeded
                                          the value specified by the
                                          maxhits constraint. Server
                                          will still reply with as many
                                          records as "maxhits" allows.

111 Requested constraint not supported    One or more constraints in
                                          query is not implemented, but
                                          the search is still done.

112 Requested constraint not fullfilled   One or more constraints in
                                          query has unacceptable value
                                          and was therefore not used,
                                          but the search is still done.

200 Command Ok                            Command accepted and executed.
                                          The client must wait for a
                                          transaction end system message.

201 Command Completed successfully        Command accepted and executed.

203 Bye                                   Server is closing connection

220 Service Ready                         Greeting message. Server is
                                          accepting commands.

226 Transaction complete                  End of data. All responses to
                                          query are sent.

430 Authentication needed                 Client requested information
                                          that needs authentication.

500 Syntax error

502 Search expression too complicated     This message is sent when the
                                          server is not able to resolve
                                          a query (i.e. when a client
                                          sent a regular expression that

                                          is too deeply nested).

530 Authentication failed                 The authentication phase
                                          failed.

600 <token>                               Subsequent attribute values
                                          are encoded in the charater
                                          set specified by <token>.

                    Table V - System response codes

------------------------------------------------------------------------

Appendix F - The WHOIS++ BNF Grammar

   whois-command   =   ( system-command [":" "hold"]
                       / terms [":" globalcnstrnts] ) NL

   system-command  =   "constraints"
                       / "describe"
                       / "commands"
                       / "polled-by"
                       / "polled-for"
                       / "version"
                       / "list"
                       / "show" [1*SP string]
                       / "help" [1*SP string]
                       / "?" [string]

   terms           =   and-expr *("or" and-expr)

   and-expr        =   not-expr *("and" not-expr)

   not-expr        =   ["not"] (term / ( "(" terms ")" ))

   term            =   generalterm / specificterm
                       / shorthandle / combinedterm

   generalterm     =   string *(";" localcnstrnt)

   specificterm    =   specificname "=" string
                       *(";" localcnstrnt)

   specificname    =   "handle" / "value"

   shorthandle     =   "!" string *(";" localcnstrnt)

   combinedterm    =   string "=" string *(";" localcnstrnt)

   globalcnstrnts  =   globalcnstrnt *(";" globalcnstrnt)

   globalcnstrnt   =   localcnstrnt
                       / "format" "=" format
                       / "maxfull" "=" 1*digit
                       / "maxhits" "=" 1*digit
                       / opt-globalcnst

   opt-globalcnst  =   "hold"
                       / "authenticate" "=" auth-method
                       / "name" "=" string
                       / "password" "=" string
                       / "language" "=" language
                       / "incharset" "=" characterset
                       / "ignore" "=" string
                       / "include" "=" string

   format          =   "full" / "abridged" / "handle" / "summary"
                       / "server-to-ask"

   language        = <The language code defined in RFC1766 [ALVE95]>

   characterset    =   "us-ascii" / "iso-8859-1" / "iso-8859-2" /
                       "iso-8859-3" / "iso-8859-4" / "iso-8859-5" /
                       "iso-8859-6" / "iso-8859-7" / "iso-8859-8" /
                       "iso-8859-9" / "iso-8859-10" / "utf-8" /
                       charset-value

   charset-value   =   1*char

   localcnstrnt    =   "search" "=" searchvalue /
                       "case" "=" casevalue

   searchvalue     =   "exact" / "substring" / "regex" / "fuzzy"
                       / "lstring"

   casevalue       =   "ignore" / "consider"

   auth-method     =   "password"

   string          =   0*char

   char            =   "\" specialchar
                       / <Characters 0-255 (decimal) except specialchar>

   specialchar     =   " " / <tab> / "=" / "," / ":" / ";" / "\" /
                       "*" / "." / "(" / ")" / "[" / "]" / "^" /
                       "$" / "!" / "?"

   digit           =   "0" / "1" / "2" / "3" / "4" /
                       "5" / "6" / "7" / "8" / "9"

   NL              =   <CR LF (decimal 13 10)>

   NOTE: Significant blanks must be escaped.  The following
   characters, when significant to the query, may be preceded
   and/or followed by a single blank:

     : ; , ( ) = !

Appendix G - Description of Regular expressions

   The regular expressions described in this section is the same as used
   in many other applications and operating systems. It is though very
   simple and does not include logical operators AND and OR.

   Searches using regular expressions are always using substring
   matching except when the regular expression contains the characters
   '^' or '$'.

       Character                                Function
       ---------                                --------

        <any except those listed in this table> Matches itself

        .                                       Matches any character

        a*                                      Matches zero or more 'a'

        [ab]                                    Matches 'a' or 'b'

        [a-c]                                   Matches 'a', 'b' or 'c'

        ^                                       Matches beginning of
                                                a token

        $                                       Matches end of a token

          Examples
          ---------

            String         Matches       Matches not
            -------        -------       -----------
             hello          xhelloy         heello
             h.llo          hello           helio
             h.*o           hello           helloa
             h[a-f]llo      hello           hgllo
             ^he.*          hello           ehello
             .*lo$          hello           helloo

 

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