Internet Engineering Task Force
Internet Draft                                                     J. Rosenberg
Internet-Draft                                               dynamicsoft
Expires: December 29, 2003                                H. Schulzrinne
                                                     Columbia U.
draft-ietf-sipping-conference-package-00.txt University
                                                           June 24, 2002
Expires: December 2002 30, 2003

    A Session Initiation Protocol (SIP) Event Package for Conference


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.


   This document defines a conference event package for the SIP Session
   Initiation Protocol (SIP) Events
   architecture, framework, along with a data format
   used in notifications for this package. The conference package allows
   users to subscribe to a SIP
   URI that is associated with a conference. conference URI. Notifications are sent about
   changes in the membership of this conference, changes in active
   speaker, the state of the
   dialogs that compose the conference, and media mixing information. general information about
   the conference.

Table of Contents


   1.    Introduction ........................................    4
   2 . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.    Terminology .........................................  . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.    Conference Event Package ............................    4 . . . . . . . . . . . . . . . . . .  5
   3.1   Event Package Name .................................. . . . . . . . . . . . . . . . . . . . . .  5
   3.2   Event Package Parameters ............................ . . . . . . . . . . . . . . . . . .  5
   3.3   SUBSCRIBE Bodies ....................................    5 . . . . . . . . . . . . . . . . . . . . . .  6
   3.4   Subscription Duration ...............................  . . . . . . . . . . . . . . . . . . .  6
   3.5   NOTIFY Bodies .......................................  . . . . . . . . . . . . . . . . . . . . . . .  6
   3.6   Notifier Processing of SUBSCRIBE Requests ...........    6  . . . . . . . . .  7
   3.7   Notifier Generation of NOTIFY Requests ..............    6 . . . . . . . . . . .  7
   3.8   Subscriber Processing of NOTIFY Requests ............    6 . . . . . . . . . .  7
   3.9   Handling of Forked Requests .........................    7  . . . . . . . . . . . . . . . .  8
   3.10  Rate of Notifications ...............................    7  . . . . . . . . . . . . . . . . . . .  8
   3.11  State Agents ........................................    7
   4 . . . . . . . . . . . . . . . . . . . . . . . .  8
   4.    Conference Data Format ..............................    7 . . . . . . . . . . . . . . . . . . .  9
   4.1   Structute of the Format .............................    8  . . . . . . . . . . . . . . . . . .  9
   4.1.1      User Conferencing Service Element ........................................    8
   4.1.2      Status .............................................. . . . . . . . . . . . . . . . .  9
   4.1.2 User Element . . . . . . . . . . . . . . . . . . . . . . . . 10
   4.1.3      Dialog ..............................................    9 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   4.1.4 Dialog . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   4.1.5 Media Status ........................................    9 Streams  . . . . . . . . . . . . . . . . . . . . . . . 11
   4.2   Constructing Coherent State .........................    9  . . . . . . . . . . . . . . . . 12
   4.3   Schema ..............................................   10 . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
   4.4   Example .............................................   13
   5  . . . . . . . . . . . . . . . . . . . . . . . . . . 15
   5.    Security Considerations .............................   13
   6  . . . . . . . . . . . . . . . . . . 16
   6.    IANA Considerations .................................   13  . . . . . . . . . . . . . . . . . . . . 17
   6.1   conference Event Package Registration  . . . . . . . . . . . 17
   6.2   application/conference-info+xml MIME Registration
   ................................................................   13
   6.2  . . . . . 17
   6.3   URN Sub-Namespace Registration for
         urn:ietf:params:xml:ns:conference-info .........................   14
   7 . . . . . . . . . . . 18
   6.4   XML Schema Registration  . . . . . . . . . . . . . . . . . . 19
   7.    Acknowledgements ....................................   15
   8          Authors Addresses ...................................   15
   9 . . . . . . . . . . . . . . . . . . . . . . 20
         Normative References ................................   15
   10 . . . . . . . . . . . . . . . . . . . . 21
         Informative References ..............................   16

1 . . . . . . . . . . . . . . . . . . . 22
         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 23
         Intellectual Property and Copyright Statements . . . . . . . 24

1. Introduction

   The SIP Session Initiation Protocol (SIP) [3] Events framework [1] [2]
   defines general mechanisms for
   subscription subscribing to, and notification receiving
   notifications of, events within SIP networks. It introduces the
   notion of a package, which is a specific "instantiation" of the
   events mechanism framework for a well-defined set of events. Packages have been
   defined for user presence [9], [11], watcher information [10], [12], and message
   waiting indicators [11], [14], amongst others. Here, we define an event
   package for SIP conferences. This package will work for any provides the conference
   notification service as outlined in which there is a central
   signaling element [12].

   The the SIP conferencing package allows framework
   [15]. As described there, subscriptions to a subscriber conference URI are
   routed to learn about the
   identities of participants and their status in focus that is handling the conference, conference. It acts as the
   dialogs that are used
   notifer, and provides clients with updates on conference state.

   The information provided by each user, this package is broken into several
   general categories:

   General State: A small amount of general conference state is
      provided, primarily for the purposes of bootstrapping access to
      other conference services, such as media makeup and conference policy

   Membership State: The members of the conference, and their state
      within the mixing matrix (i.e., who is receiving whose
   audio). This information is vital to building conferencing
   applications using SIP.

2 Terminology

   In this document, conference.

   Dialog State: The state of the dialogs for users connected to the

   Media State: Information about what media users in the conference are

2. Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   and "OPTIONAL" are to be interpreted as described in RFC 2119 [2] [1] and
   indicate requirement levels for compliant implementations.


3. Conference Event Package

   The conference event package allows a user to subscribe to a
   conference. In SIP, conferences are represented by URIs. These URIs
   route to a SIP user agent agent, called a focus, that is responsible for
   ensuring that all users in the conference can communicate with each other. Detailed
   information on conferencing models can be found in [12]. This package
   can work with any of the tightly-coupled models described in that
   specification. However, the conference server may not have complete
   information on the media makeup of the conference. This is the case
   for multicast-based conferences, where the server cannot know the
   mixing matrix for the conference. In this case, that information
   would simply not be reported through this package.
   other [15]. The specific focus has sufficient information conveyed in notifications in this package

        o The SIP URI identifying about the user.

        o The dialog state associated with that users attachment to the

        o Their status in the conference (active, declined, departed).

        o Their status in terms of receiving media in
   the conference. conference to inform subscribers about it.

   This section provides the details for defining a SIP Events package,
   as specified by [1]. [2].

3.1 Event Package Name

   The name of this event package is "conference". This package name is
   carried in the Event and Allow-Events header, as defined in [1]. [2].

3.2 Event Package Parameters

   A single parameter, "recurse" is

   Two Event header field parameters are defined for this package. The
   first is "recurse". The parameter has no values. When present, it
   informs the server that it should check whether any participants in
   the conference are themselves conferences, a focus, and if so, generate a
   subscription to their conference state with the "recurse" attribute.
   The focus can determine whether a participant is a focus based on the
   presence of the "isfocus" capability indication in the Contact header
   field provided by the participant [4]. The users reported in
   notifications from this recursed subscription are reported to the
   original subscriber. The result is that the list of users reported to
   the subscriber represents the complete user list even when cascaded
   conferences are used.

   The second Event header field parameter is "type". Its value is a
   comma separated list of the types of conference information that are
   desired. This specification defines four values - "general",
   "membership", "dialog", and "basic-media". When any one of these is
   present, it means that the corresponding conference information is
   desired. The specific components of a conference information document
   corresponding to each of these values are described below. Additional
   values for this parameter MAY be defined by extensions to this
   package. Such extensions are anticipated to handle membership and
   media policy state.

   Both of these parameters MUST have the same value in a initial
   SUBSCRIBE request and any refreshes of the resulting subscription. In
   other words, their values are fixed for the duration of the
   subscription. The default meaning of the "type" parameter, when not
   present, is that the focus should send all information it has about
   the conference. When present, the type parameter MUST have at least
   one value.

   The BNF for these parameters is:

   recurse     = "recurse"
   type        = "type" EQUAL SWS DQUOTE conf-info *("," conf-info)
                    ;; EQUAL, SWS, DQUOTE from RFC3261
   conf-info   = "general" | "membership" | "dialog" | "basic-media" |


   Event: conference;recurse conference;recurse;type="membership,general"

3.3 SUBSCRIBE Bodies

   A SUBSCRIBE for a dialog package MAY contain a body. This body
   defines a filter to apply to the subscription. Filter documents are
   not specified in this document, and at the time of writing, are
   expected to be the subject of future standardization activity.

   A SUBSCRIBE for a conference dialog package MAY be sent without a body. This
   implies the default subscription filtering policy. The default policy

   o  Notifications are generated every time there is any change in the set
      state of users participating in the conference, or a where that change
          their state (dialog state, media mixing state, etc.) is in a piece of
      information that the subscriber has indicated (using the "type"
      Event header field parameter) an interest in receiving.

   o  Notifications do not normally contain full state; rather, they
      only indicate the state of the participant whose state that has changed. The exception is a
      NOTIFY sent in response to a SUBSCRIBE. These NOTIFYs contain the complete view
      full state of
          conference state.

        o For a given user, the notifications contain the identity information and status. requested by the subscriber.

3.4 Subscription Duration

   The default expiration time for a subscription to a conference is one
   hour. Of course, once Once the conference ends, all subscriptions to that particular
   conference are terminated, with a reason of "noresource"
   [1]. [2].

3.5 NOTIFY Bodies

   As described in RFC 3265 [2], the NOTIFY message will contain bodies
   that describe the state of the subscribed resource. This body is in a
   format listed in the Accept header field of the SUBSCRIBE, or a
   package-specific default if the Accept header field was omitted from

   In this event package, the body of the notification contains a
   conference information document. This document describes the state of
   a conference. All implementations subscribers and notifiers MUST support the type
   "application/conference-info+xml", defined
   "application/conference-info+xml" data format described in Section 4. Other
   formats MAY be supported.

   When a client generates a SUBSCRIBE request, and that
   The subscribe request
   contains MAY contain an Accept header, the "application/conference-info+xml"
   format MUST be included in the header. Other formats MAY be listed.
   The header field. If no such
   header field is present, it has a default value for of "application/
   conference-info+xml". If the Accept header when it field is not present in a
   request is "application/conference-info+xml". present, it MUST include
   "application/conference-info+xml", and MAY include any other types
   capable of representing dialog state.

   Of course, the notifications generated by the server MUST be in one
   of the formats specified in the Accept header field in the SUBSCRIBE

3.6 Notifier Processing of SUBSCRIBE Requests

   The conference information contains very sensitive information.
   Therefore, all subscriptions SHOULD be authenticated and then
   authorized before approval. Authorization policy is at the discretion
   of the administrator, as always. However, a few recommendations can
   be made.

   It is RECOMMENDED that all users in the conference be allowed to
   subscribe to the conference.

3.7 Notifier Generation of NOTIFY Requests

   Notifications SHOULD be generated for the conference whenever there
   is a change in the state in any of the information types requested by
   the subscriber. For "membership", these changes generally occur when
   a new participant joins, a participant leaves, and a dial-out attempt
   succeeds or fails. Notifications MAY be generated for the conference
   whenever For "dialog", these changes occur when a dialog is
   created, terminated, or updated through a target refresh request. For
   "basic-media", these changes occur when the media mixing status of types receive by a user changes.
   participant change. For "general", these changes occur when the
   conference policy protocol URIs change.

3.8 Subscriber Processing of NOTIFY Requests

   The SIP Events framework expects packages to specify how a subscriber
   processes NOTIFY requests in any package specific ways, and in
   particular, how it uses the NOTIFY requests to contruct a coherent
   view of the state of the subscribed resource.

   Typically, the NOTIFY for the conference package will only contain
   information about those users whose state in the conference has
   changed. To construct a coherent view of the total state of all
   users, a subscriber to the dialog package will need to combine
   NOTIFYs received over time.

   Notifications within this package can convey partial information;
   that is, they can indicate information about a subset of the state
   associated with the subscription. This means that an explicit
   algorithm needs to be defined in order to construct coherent and
   consistent state. The details of this mechanism are specific to the
   particular document type. See Section 4.2 for information on
   constructing coherent information from an application/conference-
   info+xml application/
   conference-info+xml document.

3.9 Handling of Forked Requests

   By their nature, the conferences supported by this package are
   centralized. Therefore, SUBSCRIBE requests for a conference should
   not generally fork. Users of this package MUST NOT install more than
   a single subscription as a result of a single SUBSCRIBE request.

3.10 Rate of Notifications

   For reasons of congestion control, it is important that the rate of
   notifications not become excessive. As a result, it is RECOMMENDED
   that the server not generate notifications for a single subscriber at
   a rate faster than once every 5 seconds.

3.11 State Agents

   Conference state is ideally maintained in the element in which the
   conference resides. Therefore, the elements that maintain the
   conference are the ones best suited to handle subscriptions to it.
   Therefore, the usage of state agents is NOT RECOMMENDED for this


4. Conference Data Format

   Conference information is an XML document [3] [5] that MUST be well-
   well-formed and SHOULD be valid. Dialog information documents MUST be
   based on XML 1.0 and MUST be encoded using UTF-8. This specification
   makes use of XML namespaces for identifying dialog information
   documents and document fragments. The namespace URI for elements
   defined by this specification is a URN [4], [6], using the namespace
   identifier 'ietf' defined by [5] [7] and extended by [6]. [8]. This URN is:


   A conference information document begins with the root element tag

4.1 Structute of the Format

   Conference information begins with the top level element
   "conference-info". This element has three mandatory attributes:

   version: This attribute allows the recipient of conference
      information documents to properly order them. Versions start at 0,
      and increment by one for each new document sent to a subscriber.
      Versions are scoped within a subscription. Versions MUST be
      representable using a 32 bit integer.

   state: This attribute indicates whether the document contains the
      full conference information, or whether it contains only the
      information on those users whose state have that has changed since the previous document

   entity: This attribute contains a the conference URI that identifies
      the conference whose information is reported being described in the remainder
             of the document.

   The "conference-info" element has zero or more "conf-service"
   elements, which provide URIs for access conferencing services, such
   as media policy and conference policy control. This is followed by
   zero or more "user" sub-elements which contain information on the
   users in the conference.

4.1.1 Conferencing Service Element

   The "conf-service" element contains a URI that can be used to access
   some additional conferencing service. The element contains the
   following attributes:

   id: This attribute provides a unique identifier (unique within the
      context of the subscription) for the service. The attribute is

   type: This attribute contains a string which indicates the type of
      service. Defined values are "conf-policy", to indicate that the
      URI is for manipulating the conference policy [17][18],
      "media-policy", to indicate that the URI is for manipulating the
      media policy [9], and "floor-control", to indicate that the URI is
      for access to floor control services [19]. The attribute is

   There MUST only be one conf-service for each type of service.
   Additional service types may be defined in the future.

      OPEN ISSUE: Once a protocol becomes solidified, we will need to
      add some additional content here. For example, if XCAP [16] is
      used, the AUID should be provided here. We may want to move to a
      model where each service type is a unique XML element; that would
      allow for the schema to impose the contraint on a single URI for
      each service type.

   The "conf-service" element is only provided in notifications if the
   subscriber included the value of "general" in its "type" Event header
   field parameter.

4.1.2 User Element

   Each user element has zero or one "status" elements, indicating their
   status in the conference, zero or one "dialog" elements, indicating
   their dialog information, and zero or one "media-state" "media-streams" elements,
   indicating their media reception information.

   The user element has one mandatory attribute, "uri" that indicates
   the URI for the user in the conference. This is a logical identifier,
   not a machine specific one (i.e., its taken from the To/From, not authenticated
   identity of the
   Contact). participant). The optional attribute "display-name"
   contains a display name for the user. The standard "xml:lang"
   language attribute can also be present to indicate the language of
   the display name.


4.1.3 Status

   The status element contains the status of the user in the conference.
   The following statuses are defined:

   active: The user is in an active dialog with the conference
             host. focus.

   departed: The user sent a BYE, thus leaving the conference.

   booted: The user was sent a BYE by the conference host, booting them
      out of the conference.

   failed: The server tried to bring the user into the conference, but
      its attempt to contact the specific user resulted in a non-200
      class final response.


   The "status" element is only provided in notifications if the
   subscriber included the value of "membership" in its "type" Event
   header field parameter.

4.1.4 Dialog

   The dialog element is defined in [7].

4.1.4 [13]. It is presented from the
   viewpoint of the focus. The "dialog" element is only provided in
   notifications if the subscriber included the value of "dialog" in its
   "type" Event header field parameter.

4.1.5 Media Status Streams

   The "media-status" "media-streams" element indicates the types of media streams that the user
   is currently receiving connected to. Here, "connected to" implies that a user
   has a media line in their SDP [20] which is associated with a media
   stream managed by the conference. It consists focus (see Section 2.1 of [9]). With this
   definition, a series of
   "media-stream" sub-elements, each of one describes user is connected to a particular media
   stream. Each "media-stream" stream even if they are
   not sending any media.

   The "media-streams" element has a mandatory "media-type"
   attribute that indicates the MIME media type for zero or more "media-stream"
   sub-elements. The value of the stream. There "media-stream" element is
   also an optional "send-status" and "recv-status" attribute which
   attribute which indicates the status of the media to/from that user.

   identifier, unique within the "send-status" is "received-by-all", it means that conference, which identifies the media
   for that
   stream that is being generated by the a user is being mixed by
   the server and sent connected to all recipients. "muted" means that no one is
   receiving their media. If it is "unknown", the server does not know [9]. The "media-stream" element
   also has a mandatory "media-type" attribute which identifies the status, perhaps because
   media type (audio, video, message and application) of the media

   The "media-streams" element is being distributed via
   multicast or multi-unicast.

   If only provided in notifications if the "recv-status" is "receiving-all" it means that
   subscriber included the user is
   hearing all other participants. If it is "anchor-only", value of "basic-media" in its "type" Event
   header field parameter.

      OPEN ISSUE: This needs to be aligned with the user is
   hearing final media from just a single participant. policy
      mechanisms done in xcon. If it is "unknown", the
   server does not know the status, perhaps because the we wish this draft to proceed
      independently, we should probably remove any notion of media is being
   distributed via multicast or multi-unicast.

4.2 Constructing Coherent State

   The conference information subscriber maintains a table for the list
   of users in the conference. The table contains a row for each user.
   Each row is indexed by a URI, present in the "uri" attribute of the
   "user" element. The contents of each row contain the state of that
   user as conveyed in the document. The subscriber also maintains a
   table for the service URIs in the conference. This table contains a
   row for each service type. Each row is also indexed by a token, present in
   the "id" attribute of the "conf-service" element. The contents of the
   row contain the URI and type of that service.

   Both tables are associated with a version number. The version number
   MUST be initialized with the value of the "version" attribute from
   the "conference-info" element in the first document received. Each
   time a new document is received, the value of the local version
   number, and the "version" attribute in the new document, are
   compared. If the value in the new document is one higher than the
   local version number, the local version number is increased by one,
   and the document is processed. If the value in the document is more
   than one higher than the local version number, the local version
   number is set to the value in the new document, the document is
   processed, and the subscriber SHOULD generate a refresh request to
   trigger a full state notification. If the value in the document is
   less than the local version, the document is discarded without

   The processing of the conference information document depends on
   whether it contains full or partial state. If it contains full state,
   indicated by the value of the "state" attribute in the "conference-
   "conference-info" element, the contents of the table both tables are flushed.
   They are repopulated from the document. A new row in the user table
   is created for each "user" element, and a new row in the conferencing
   services table is created for each "conf-service" element. If the
   document contains partial state, as indicated by the value of the
   "state" attribute in the "conference-
   info" "conference-info" element, the document is
   used to update the table. tables. For each "user" element in the document,
   the subscriber checks to see whether a row exists for that user. user in
   the user table. This check is done by comparing the URI in the "uri"
   attribute of the "user" element with the URI associated with the row.
   If the user doesn't exist in the table, a row is added, and its state
   is set to the information from that "user" element. If the user does
   exist, its state is updated to be the information from that "user"
   element. If a row is updated or created, such that its state is now
   booted, failed or departed, that entry MAY be removed from the table
   at any time.

4.3 Schema

   The following is

   Similarly, for each each "conf-service" element in the schema document, the
   subscriber checks to see whether a row exists for that service in the application/conference-info+xml
   service table. This check is done by comparing the id in the "id"
   attribute of the "conf-service" element with the id associated with
   the row. If the service doesn't exist in the table, a row is added,
   and its URI and type are set to be the information from the
   "conf-service" element. Since it is not expected that this
   information will change during the lifetime of the conference, there
   is no way to indicate removal of a service.

      OPEN ISSUE: Is this really the right way to bootstrap these URIs?
      The information really is static, and placing it in an event
      package will result in a waste of bandwidth during full-state

4.3 Schema

   <?xml version="1.0" encoding="UTF-8"?>
     elementFormDefault="qualified" attributeFormDefault="unqualified">
     <!-- This import brings in the XML language attribute xml:lang-->
     <xs:import namespace=""
     <!-- This import brings in the dialog-info element dialog-->
     <xs:import namespace="urn:ietf:params:xml:ns:dialog-info"
     <xs:element name="conference-info">
       <xs:complexType name="c-info-type">
           <xs:element name="conf-service" type="tns:conf-serviceType"
              minOccurs="0" maxOccurs="unbounded"/>
           <xs:element name="user" type="tns:user-type" type="user-type"
              minOccurs="0" maxOccurs="unbounded"/>
           <xs:any namespace="##other" processContents="lax"
              minOccurs="0" maxOccurs="unbounded"/>
         <xs:attribute name="version" type="xs:nonNegativeInteger"
         <xs:attribute name="state" use="required">
             <xs:restriction base="xs:string">
               <xs:enumeration value="full"/>
               <xs:enumeration value="partial"/>
         <xs:attribute name="entity" type="xs:anyURI" use="required"/>
     <xs:complexType name="user-type">
         <xs:element name="status" type="tns:status-type" minOccurs="0"/>
         <xs:element ref="di:dialog" minOccurs="0"/>
         <xs:element name="media-status" name="media-streams" minOccurs="0">
           <xs:complexType name="media-status-type">
               <xs:element name="media-stream"
                  minOccurs="0" maxOccurs="unbounded"/>
               <xs:any namespace="##other" processContents="lax"
                  minOccurs="0" maxOccurs="unbounded"/>
       <xs:attribute name="uri" type="xs:anyURI" use="required"/>
       <xs:attribute name="display-name" type="xs:string" use="optional"/>
       <xs:attribute ref="xml:lang"/> ref="xml:lang" use="optional"/>
     <xs:complexType name="status-type"> name="media-stream-type">
         <xs:extension base="xs:string">
           <xs:enumeration value="active"/>
           <xs:enumeration value="departed"/>
           <xs:enumeration value="booted"/>
           <xs:enumeration value="failed"/>
     <xs:complexType name="media-stream-type">
           <xs:attribute name="media-type" type="tns:mimetypes"
       <xs:attribute name="send-status" type="tns:send-status-type"
       <xs:attribute name="recv-status" type="tns:recv-status-type"
     <xs:simpleType name="mimetypes">
       <xs:restriction base="xs:string">
         <xs:enumeration value="audio"/>
         <xs:enumeration value="video"/>
         <xs:enumeration value="message"/>
         <xs:enumeration value="application"/>
     <xs:complexType name="conf-serviceType">
         <xs:extension base="xs:anyURI">
           <xs:attribute name="id" type="xs:string" use="required"/>
           <xs:attribute name="type" type="tns:typeType" use="required"/>
     <xs:simpleType name="send-status-type"> name="typeType">
       <xs:restriction base="xs:string">
         <xs:enumeration value="received-by-all"/> value="conf-policy"/>
         <xs:enumeration value="muted"/> value="media-policy"/>
         <xs:enumeration value="unknown"/> value="floor-control"/>
     <xs:simpleType name="recv-status-type"> name="status-type">
       <xs:restriction base="xs:string">
        <xs:enumeration value="receiving-all"/>
        <xs:enumeration value="anchor-only"/>
         <xs:enumeration value="unknown"/>

        OPEN ISSUE: We need to register the schema for the dialog
        info package in order to have a stable reference for it in
        the conference info schema above. base="xs:string">
         <xs:enumeration value="active"/>
         <xs:enumeration value="departed"/>
         <xs:enumeration value="booted"/>
         <xs:enumeration value="failed"/>

4.4 Example

   The following is an example conference information document:

   <conference-info version="0" state="full" entity=""> entity="">
     <user uri="" uri="" display-name="Jonathan Rosenberg">
         <media-stream media-type="audio"/>
       </media-status> media-type="audio">8hha7</media-stream>
     <user uri="" uri="" display-name="Henning Schulzrinne">

   This document describes a conference with two users, both of which
   are active.


5. Security Considerations

   Subscriptions to conference state can reveal very sensitive
   information. For this reason, the document recommends authentication
   and authorization, and provides guidelines on sensible authorization

   Since the data in notifications is sensitive as well, end-to-end SIP
   encryption mechanisms using S/MIME SHOULD be used to protect it.


6. IANA Considerations

   This document registers a SIP event package, a new MIME type, application/conference-
   application/conference-info+xml, a new XML namespace, and registers a new XML namespace.

6.1 conference Event Package Registration

   This specification registers an event package, based on the
   registration procedures defined in RFC 3265 [2]. The following is the
   information required for such a registration:

   Package Name: conference

   Package or Template-Package: This is a package.

   Published Document: RFC XXXX (Note to RFC Editor: Please fill in XXXX
      with the RFC number of this specification).

   Person to Contact: Jonathan Rosenberg,

6.2 application/conference-info+xml MIME Registration

   MIME media type name: application

   MIME subtype name: conference-info+xml

   Mandatory parameters: none

   Optional parameters: Same as charset parameter application/xml as
      specified in RFC 3023 [8]. [10].

   Encoding considerations: Same as encoding considerations of
      application/xml as specified in RFC 3023 [8]. [10].

   Security considerations: See Section 10 of RFC 3023 [8] [10] and Section
      5 of this specification.

   Interoperability considerations: none.

   Published specification: This document.

   Applications which use this media type: This document type has been
      used to support SIP conferencing applications.

   Additional Information:

      Magic Number: None

      File Extension: .cif or .xml

      Macintosh file type code: "TEXT"

   Personal and email address for further information: Jonathan
      Rosenberg, <>

   Intended usage: COMMON

   Author/Change controller: The IETF.


6.3 URN Sub-Namespace Registration for

   This section registers a new XML namespace, as per the guidelines in

   URI: The URI for this namespace is

   Registrant Contact: IETF, SIMPLE SIPPING working group,
             <>, <>,
      Jonathan Rosenberg <>.


   <?xml version="1.0"?>
   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
   <html xmlns="">
     <meta http-equiv="content-type"
     <title>Dialog Information Namespace</title>
     <h1>Namespace for Dialog Information</h1>
     <p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>


6.4 XML Schema Registration

   This specification registers a schema, as per the guidelines in in

      URI: please assign.

      Registrant Contact: IETF, SIPPING Working Group
      (, Jonathan Rosenberg (

      XML: The XML can be found as the sole content of Section 4.3.

7. Acknowledgements

   The authors would like to thank Dan Petrie ans and Sean Olson for their

8 Authors Addresses

   Jonathan Rosenberg
   72 Eagle Rock Avenue
   First Floor
   East Hanover, NJ 07936

   Henning Schulzrinne
   Columbia University
   M/S 0401
   1214 Amsterdam Ave.
   New York, NY 10027-7003


Normative References

   [1] A. Roach, "SIP-specific event notification," Internet Draft,
   Internet Engineering Task Force, Mar. 2002.  Work in progress.

   [2] S.   Bradner, S., "Key words for use in RFCs to indicate requirement
   levels," Indicate Requirement
         Levels", BCP 14, RFC 2119, Internet Engineering Task Force, Mar. March 1997.

   [2]   Roach, A., "Session Initiation Protocol (SIP)-Specific Event
         Notification", RFC 3265, June 2002.

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

   [4]   Rosenberg, J., "Indicating User Agent Capabilities in the
         Session Initiation Protocol  (SIP)",
         draft-ietf-sip-callee-caps-00 (work in progress), June 2003.

   [5]   Bray, T., Paoli, J., Sperberg-McQueen, C. (W3C), and E. Maler,
         "Extensible markup language (xml) 1.0." The
   XML Markup Language (XML) 1.0 spec can be found at

   [4] R. (Second Edition)", W3C
         REC REC-xml-20001006, October 2000.

   [6]   Moats, R., "URN syntax," Syntax", RFC 2141, Internet Engineering Task
   Force, May 1997.

   [5] R.

   [7]   Moats, R., "A URN namespace Namespace for IETF documents," Documents", RFC 2648,
   Internet Engineering Task Force, Aug.
         August 1999.

   [6] M.

   [8]   Mealling, M., "The IANA IETF XML registry," Internet Draft, Internet
   Engineering Task Force, Nov. 2001.  Work Registry",
         draft-mealling-iana-xmlns-registry-05 (work in progress.

   [7] J. Rosenberg and H. Schulzrinne, "A session initiation protocol
   (SIP) event package for dialog state," Internet Draft, Internet
   Engineering Task Force, progress), June 2002.  Work

   [9]   Mahy, R. and N. Ismail, "Media Policy Manipulation in progress.

   [8] M. the
         Conference Policy Control Protocol",
         draft-mahy-xcon-media-policy-control-00 (work in progress),
         June 2003.

   [10]  Murata, S. S. M., St. Laurent, S. and D. Kohn, "XML media types," Media Types", RFC
         3023, Internet Engineering Task Force, Jan. January 2001.


Informative References

   [9] J.

   [11]  Rosenberg, J., "A Presence Event Package for the Session
         Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work
         in progress), January 2003.

   [12]  Rosenberg, "Session initiation protocol (SIP) extensions J., "A Watcher Information Event Template-Package
   presence," Internet Draft, Internet Engineering Task Force, May 2002.
   Work in progress.

   [10] the Session Initiation  Protocol (SIP)",
         draft-ietf-simple-winfo-package-05 (work in progress), January

   [13]  Rosenberg, J. and H. Schulzrinne, "An INVITE Inititiated Dialog
         Event Package for the Session Initiation  Protocol (SIP",
         draft-ietf-sipping-dialog-package-01 (work in progress), March

   [14]  Mahy, R., "A Message Summary and Message Waiting Indication
         Event Package for the  Session Initiation Protocol (SIP)",
         draft-ietf-sipping-mwi-03 (work in progress), July 2003.

   [15]  Rosenberg, J., "A session initiation protocol (SIP)event
   template-package Framework for watcher information," Internet Draft, Internet
   Engineering Task Force, Conferencing with the Session
         Initiation Protocol",
         draft-ietf-sipping-conferencing-framework-00 (work in
         progress), May 2002.  Work 2003.

   [16]  Rosenberg, J., "The Extensible Markup Language (XML)
         Configuration Access Protocol  (XCAP)",
         draft-ietf-simple-xcap-00 (work in progress.

   [11] R. Mahy, "A message summary progress), June 2003.

   [17]  Koskelainen, P. and message waiting indication event
   package H. Khartabil, "An Extensible Markup
         Language (XML) Configuration Access Protocol (XCAP)  Usage for the session initiation protocol (SIP)," Internet Draft,
   Internet Engineering Task Force,
         Conference Policy Manipulation",
         draft-koskelainen-xcon-xcap-cpcp-usage-00 (work in progress),
         June 2002.  Work 2003.

   [18]  Levin, O., "Conference Policy Control Protocol for Centralized
         Conferencing", draft-levin-xcon-cpcp-00 (work in progress.

   [12] J. Rosenberg progress),
         June 2003.

   [19]  Wu, X., "Use of Session Initiation Protocol (SIP) and H. Schulzrinne, "Models Simple
         Object Access  Protocol (SOAP) for multi party
   conferencing Conference Floor Control
         Protocol (SOAP) for Conference Floor Control",
         draft-wu-sipping-floor-control-04 (work in progress), March

   [20]  Handley, M. and V. Jacobson, "SDP: Session Description
         Protocol", RFC 2327, April 1998.

Authors' Addresses

   Jonathan Rosenberg
   600 Lanidex Plaza
   Parsippany, NJ  07054

   Phone: +1 973 952-5000

   Henning Schulzrinne
   Columbia University
   M/S 0401
   1214 Amsterdam Ave.
   New York, NY  10027


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