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SIPPING                                                     J. Rosenberg
Internet-Draft                                             Cisco Systems
Expires: September 26, 2005                               H. Schulzrinne
                                                     Columbia University
                                                           O. Levin, Ed.
                                                   Microsoft Corporation
                                                          March 25, 2005


    A Session Initiation Protocol (SIP) Event Package for Conference
                                 State
                draft-ietf-sipping-conference-package-10

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of Section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
   which he or she is aware have been or will be disclosed, and any of
   which he or she become aware will be disclosed, in accordance with
   RFC 3668.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 26, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document defines a conference event package for the Session
   Initiation Protocol (SIP) Events framework, along with a data format



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   used in notifications for this package.  The conference package
   allows users to subscribe to a conference URI.  Notifications are
   sent about changes in the membership of this conference and
   optionally about changes in the state of additional conference
   components.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Conference Event Package . . . . . . . . . . . . . . . . . . .  4
     3.1   Event Package Name . . . . . . . . . . . . . . . . . . . .  4
     3.2   SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . .  5
     3.3   Subscription Duration  . . . . . . . . . . . . . . . . . .  5
     3.4   NOTIFY Bodies  . . . . . . . . . . . . . . . . . . . . . .  5
     3.5   Notifier Processing of SUBSCRIBE Requests  . . . . . . . .  6
     3.6   Notifier Generation of NOTIFY Requests . . . . . . . . . .  6
     3.7   Subscriber Processing of NOTIFY Requests . . . . . . . . .  6
     3.8   Handling of Forked Requests  . . . . . . . . . . . . . . .  7
     3.9   Rate of Notifications  . . . . . . . . . . . . . . . . . .  7
     3.10  State Agents . . . . . . . . . . . . . . . . . . . . . . .  7
   4.  Conference Document  . . . . . . . . . . . . . . . . . . . . .  7
     4.1   Format . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.2   Namespace  . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.3   Versioning . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.4   Partial Notifications Mechanism  . . . . . . . . . . . . .  8
     4.5   Element Keys . . . . . . . . . . . . . . . . . . . . . . .  9
     4.6   Constructing Coherent State Procedure  . . . . . . . . . .  9
   5.  Conference Data  . . . . . . . . . . . . . . . . . . . . . . . 10
     5.1   <conference-info>  . . . . . . . . . . . . . . . . . . . . 11
     5.2   <conference-description> . . . . . . . . . . . . . . . . . 11
       5.2.1   <conf-uris>  . . . . . . . . . . . . . . . . . . . . . 12
       5.2.2   <service-uris> . . . . . . . . . . . . . . . . . . . . 13
       5.2.3   <maximum-user-count> . . . . . . . . . . . . . . . . . 13
       5.2.4   <available-media>  . . . . . . . . . . . . . . . . . . 13
     5.3   <host-info>  . . . . . . . . . . . . . . . . . . . . . . . 14
       5.3.1   <display-text> . . . . . . . . . . . . . . . . . . . . 14
       5.3.2   <web-page> . . . . . . . . . . . . . . . . . . . . . . 14
       5.3.3   <uris> . . . . . . . . . . . . . . . . . . . . . . . . 14
     5.4   <conference-state> . . . . . . . . . . . . . . . . . . . . 14
       5.4.1   <user-count> . . . . . . . . . . . . . . . . . . . . . 14
       5.4.2   <active> . . . . . . . . . . . . . . . . . . . . . . . 15
       5.4.3   <locked> . . . . . . . . . . . . . . . . . . . . . . . 15
     5.5   <users> of <user>  . . . . . . . . . . . . . . . . . . . . 15
       5.5.1   <display-text> . . . . . . . . . . . . . . . . . . . . 16
       5.5.2   <associated-aors>  . . . . . . . . . . . . . . . . . . 16
       5.5.3   <roles>  . . . . . . . . . . . . . . . . . . . . . . . 16
       5.5.4   <language> . . . . . . . . . . . . . . . . . . . . . . 16



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       5.5.5   <cascaded-focus> . . . . . . . . . . . . . . . . . . . 16
       5.5.6   <endpoint> . . . . . . . . . . . . . . . . . . . . . . 16
     5.6   <endpoint> . . . . . . . . . . . . . . . . . . . . . . . . 17
       5.6.1   <display-text> . . . . . . . . . . . . . . . . . . . . 17
       5.6.2   <referred> . . . . . . . . . . . . . . . . . . . . . . 17
       5.6.3   <status> . . . . . . . . . . . . . . . . . . . . . . . 18
       5.6.4   <joining-method> . . . . . . . . . . . . . . . . . . . 19
       5.6.5   <joining-info> . . . . . . . . . . . . . . . . . . . . 19
       5.6.6   <disconnection-method> . . . . . . . . . . . . . . . . 19
       5.6.7   <disconnection-info> . . . . . . . . . . . . . . . . . 20
       5.6.8   <media>  . . . . . . . . . . . . . . . . . . . . . . . 20
       5.6.9   <call-info>  . . . . . . . . . . . . . . . . . . . . . 20
     5.7   <media>  . . . . . . . . . . . . . . . . . . . . . . . . . 21
       5.7.1   <display-text> . . . . . . . . . . . . . . . . . . . . 21
       5.7.2   <type> . . . . . . . . . . . . . . . . . . . . . . . . 21
       5.7.3   <label>  . . . . . . . . . . . . . . . . . . . . . . . 21
       5.7.4   <src-id> . . . . . . . . . . . . . . . . . . . . . . . 21
       5.7.5   <status> . . . . . . . . . . . . . . . . . . . . . . . 22
     5.8   <sidebars-by-ref>  . . . . . . . . . . . . . . . . . . . . 22
     5.9   <sidebar-by-val> . . . . . . . . . . . . . . . . . . . . . 22
   6.  XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 22
   7.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
     7.1   Basic Example  . . . . . . . . . . . . . . . . . . . . . . 30
     7.2   Rich Example . . . . . . . . . . . . . . . . . . . . . . . 32
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 35
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 36
     9.1   conference Event Package Registration  . . . . . . . . . . 36
     9.2   application/conference-info+xml MIME Registration  . . . . 36
     9.3   URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:conference-info . . . . . . . . . . 37
     9.4   XML Schema Registration  . . . . . . . . . . . . . . . . . 38
     9.5   URI Purposes Sub-registry Establishment  . . . . . . . . . 38
   10.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 39
   11.   References . . . . . . . . . . . . . . . . . . . . . . . . . 39
     11.1  Normative References . . . . . . . . . . . . . . . . . . . 39
     11.2  Informative References . . . . . . . . . . . . . . . . . . 40
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 41
       Intellectual Property and Copyright Statements . . . . . . . . 43













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1.  Introduction

   The Session Initiation Protocol (SIP) Events Framework [9] defines
   general mechanisms for subscribing to, and receiving notifications
   of, events within SIP networks.  It introduces the notion of a
   package, which is a specific "instantiation" of the events framework
   for a well-defined set of events.  Here, we define an event package
   for SIP conferences.  This package provides the conference
   notification service as outlined in the SIP conferencing framework
   [19].  As described there, subscriptions to a conference URI are
   routed to the focus that is handling the conference.  It acts as the
   notifier, and provides clients with updates on conference state.

   The information provided by this package is comprised of conference
   identifier(s), conference participants (optionally with their
   statuses and media description), conference sidebars, conference
   service URIs, etc.

2.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in RFC 2119 [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, called a focus, that is responsible for
   ensuring that all users in the conference can communicate with each
   other, as described in Conferencing Framework [19].  The focus has
   sufficient information about the state of the conference to inform
   subscribers about it.

   It is possible that a participant in the conference may in fact be
   another focus.  In order to provide a more complete participant list,
   the focus MAY subscribe to the conference package of the other focus
   to discover the participant list in the cascaded conference.  This
   information can then be included in notifications by use of the
   <cascaded-focus> element as specified by this package.

   This section provides the details for defining a SIP-specific event
   notification package, as specified by RFC 3265 [9].

3.1  Event Package Name

   The name of this event package is "conference".  This package name is



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   carried in the Event and Allow-Events header, as defined in RFC 3265
   [9].

3.2  SUBSCRIBE Bodies

   A SUBSCRIBE for a conference 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 package MAY be sent without a body.
   This implies the default subscription filtering policy.  The default
   policy is:
   o  Notifications are generated every time there is any change in the
      state of the conference.
   o  Notifications do not normally contain full state; rather, they
      only indicate the state that has changed.  The exception is a
      NOTIFY sent in response to a SUBSCRIBE.  These NOTIFYs contain the
      full state of the information requested by the subscriber.

3.3  Subscription Duration

   The default expiration time for a subscription to a conference is one
   hour.  Once the conference ends, all subscriptions to that particular
   conference are terminated, with a reason of "noresource" as defined
   in RFC 3265 [9].

3.4  NOTIFY Bodies

   As described in RFC 3265 [9], 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
   the SUBSCRIBE.

   In this event package, the body of the notification contains a
   conference information document.  This document describes the state
   of a conference.  All subscribers and notifiers MUST support the
   "application/conference-info+xml" data format described in Section 5.
   The subscribe request MAY contain an Accept header field.  If no such
   header field is present, it has a default value of
   "application/conference-info+xml".  If the header field is present,
   it MUST include "application/conference-info+xml", and MAY include
   any other types.

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



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3.5  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 event package.

3.6  Notifier Generation of NOTIFY Requests

   Notifications SHOULD be generated for the conference state when a new
   participant joins (i.e.  gets "connected" to) or a participant leaves
   (i.e.  gets "disconnected" from) the conference.

   Subject to a local focus policy, additional changes in participants'
   status, changes in their media types, and other optional information
   MAY be reported by the focus.

   Changes in sidebar rosters SHOULD be reported by the focus to their
   participants and MAY be reported to others, subject to local policy.

   Changes in conference identifiers and service URIs SHOULD be reported
   by the focus to the Conference package subscribers.

   Changes in other conference state information MAY be reported by the
   focus to the Conference package subscribers.

3.7  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 construct 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 conference 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



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   particular document type.  See Section 4.6 for information on
   constructing coherent information from an
   application/conference-info+xml document.

3.8  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.

3.9  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 doesn't generate notifications for a single
   subscriber at a rate faster than once every 5 seconds.

3.10  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
   package.

4.  Conference Document

4.1  Format

   Conference information is an XML document that MUST be well-formed
   and valid.  It MUST be based on Extensible Markup Language (XML) 1.0
   and MUST be encoded using UTF-8 [12].

4.2  Namespace

   This specification makes use of XML namespaces for identifying
   conference information documents and document fragments.  The
   namespace URI for elements defined by this specification is a URN
   [2], using the namespace identifier 'ietf' defined by [6] and
   extended by RFC 3688 [13].  This URN is:

   urn:ietf:params:xml:ns:conference-info

4.3  Versioning

   The conference information is described by a hierarchal XML structure
   with the root element <conference-info>.  The root element is the



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   only element in the schema that carries meaningful version number for
   all the elements in the document.  The whole conference information
   is associated with this version number.

   The 'version' attribute MUST be included in the root
   <conference-info> element.

4.4  Partial Notifications Mechanism

   This specification defines a basic partial notifications mechanism by
   using a 'state' attribute as described below.  This mechanism MUST be
   supported by all subscribing clients.  Additional general partial
   notifications mechanisms can be defined and applied to this package
   in the future.

   All sub-elements in the <conference-info> hierarchal XML structure
   can be classified in two groups: permissible for partial
   notifications or not.  Elements that carry a substantial amount of
   data that is subject to frequent changes are permissible for partial
   notifications and have a 'state' attribute attached to them.  All
   future extensions to this schema MUST define which extension elements
   can also use this mechanism.  All other elements can be updated as
   atomic pieces of data only.

   Below is the complete list of elements permissible to use the partial
   notifications mechanism defined in this specification.  (Note that
   future partial notifications mechanisms can potentially be applicable
   to additional elements.)

   o  Element <conference-info>
   o  Element <users>
   o  Element <user>
   o  Element <endpoint>
   o  Element <sidebars-by-val>
   o  Element <sidebars-by-ref>

   The 'state' attribute value indicates whether the reported
   information about the element is "full", "partial" or the element is
   "deleted" from the conference state document.  The default value of
   any 'state' attribute is "full".

   A 'state' attribute of a child element in the document MUST adhere to
   its parent 'state'.  It means that if the parent's 'state' is "full",
   the state of its children MUST be "full".  If the parent's 'state' is
   "partial", the state of its children MAY be either "partial", "full",
   or "deleted".





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4.5  Element Keys

   The defined XML schema has a property of unique identification among
   sub-elements of a common parent, which makes it possible to use the
   partial notifications mechanism defined in this document.  This
   property is achieved by defining a key to each sub-element that can
   appear multiple times under the common parent.

   In the context of this specification, the element key is the set of
   mandatory attributes or sub-elements of an element.  The key value
   MUST be unique for the element among its siblings of the same type.

   In the context of this specification, the comparison rules for keys
   of type xs:anyURI are byte-by-byte (including all URI parameters that
   can be included with the URI).

   Below is the list of elements (subject to partial notifications of
   their parent elements) with their keys as defined by this
   specification:

   o  Element <user> uses as the key 'entity'
   o  Element <endpoint> uses as the key 'entity'
   o  Element <media> uses as the key 'id'
   o  Element <entry> (child to <sidebars-by-val>) uses as the key
      'entity'
   o  Element <sidebars-by-ref> uses as the key <uri>

4.6  Constructing Coherent State Procedure

   A conference package subscriber maintains a local version number, a
   local element for each element in the schema, and a table for each
   element with its key as defined above.

   The first time a NOTIFY with a "full" document is received (as
   indicated by the value of the 'state' attribute in the
   <conference-info> element), the conference package subscriber MUST
   set the local 'version' number to the value of the 'version'
   attribute from the received <conference-info> and populate local data
   with the received information.

   Each time a new NOTIFY is received, the value of the local version
   number and the value of the 'version' attribute in the new received
   document are compared.  If the value in the document is equal or less
   than the local version, the document is discarded without processing.

   Otherwise, if the received NOTIFY contains a "full" or "deleted"
   state, the conference package subscriber MUST set the local 'version'
   number to the value of the 'version' attribute from the received



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   <conference-info> and replace the local information with the received
   document.  Receiving "deleted" state means that the conference ceased
   to exist and the subscriber SHOULD terminate the subscription by
   sending the SUBSCRIBE with Expires = 0.

   Otherwise (i.e.  if the received NOTIFY contains "partial" state), if
   the 'version' number in the received document is more than one number
   higher than the previous local version number, the subscriber MUST
   generate a subscription refresh request to trigger a full state
   notification.  If the 'version' number in the document is one higher
   than the local version number, the local version number is updated
   accordingly and the document is used to update the local content as
   described below.

   For each sub-element of the <conference-info> element in the received
   document,

   1.  If the element contains "full" state, the whole local element
   content is flushed and repopulated from the document.

   2.  Otherwise, if the element contains "deleted" state, the whole
   element MUST be removed from the local content.

   3.  Otherwise, if the element contains "partial" state:

   3.1 For elements with keys, the subscriber compares the keys received
   in the update with the keys in the local tables.

   3.1.1 If a key does not exist in the local table, a row is added, and
   its content is set to the element information from the update.

   3.1.2 Otherwise, if a key of the same value does exist, for each
   sub-element in the row the algorithm is applied from step 3.2.

   3.2 For each atomic element received in the schema, the element is
   replaced with the new information as a whole.  Also, for each
   non-atomic element received in the schema with either no 'state'
   attribute included or the state attribute is set to "full", the
   element is replaced with the new information as a whole.

   3.3 For each non-atomic element with the state attribute set to
   "partial", the algorithm is applied recursively starting from step
   3.1.

5.  Conference Data






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5.1  <conference-info>

   A conference information document begins with the root element tag
   <conference-info> of conference-type.

   The following attributes are defined for <conference-info>:

   entity: This attribute contains the conference URI that identifies
      the conference being described in the document.

   state: This attribute indicates whether the document contains the
      whole conference information ("full"), only the information that
      has changed since the previous document ("partial"), or the
      conference ceased to exist ("deleted").  For more detail see
      Section 4.

   version: This attribute allows the recipient of conference
      information documents to properly order them and it MUST be
      included when used in the root <conference-info> element.  Version
      number is a 32 bit monotonically increasing integer scoped within
      a subscription.  A server MUST increment the version number by one
      for each new partial notification being sent to a subscriber.

   The <conference-info> element is comprised of
   <conference-description>, <host-info>, <conference-state>, <users>,
   <sidebar-by-ref> and <sidebars-by-val> child elements.  A "full"
   conference document MUST at least include the
   <conference-description> and <users> child elements.

   Following sections describe these elements in detail.  The full XML
   schema is provided in Section 6.

5.2  <conference-description>

   The <conference-description> element describes the conference as a
   whole.

   The child elements <display-text>, <subject>, <free-text>, and
   <keywords> are used to describe the conference content:

   <display-text>: Contains a text suitable for human consumption and
      directory listing

   <subject>: Contains the subject of the conference







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   <free-text>: Contains an additional longer description of the
      conference

   <keywords>: Contains a list of comma-separated keywords that can be
      used by search engines to better classify the conference

   Additional child elements <conf-uris> and <service-uris> are used to
   describe the conference-related URIs; <maximum-user-count> and
   <available-media> are used to describe the overall characteristics.

   This information is typically derived from the system conference
   policies, is set before the conference activation, and is rarely
   changed during the conference lifetime.

   The following sections describe the remaining elements in more
   detail.  Other sub-elements can extend <conference-description> in
   the future.

5.2.1  <conf-uris>

   This element is a set of <entry> child elements - each containing the
   URI to be used in order to access the conference by different
   signaling means.  The value of the URI MUST be unique in the
   conference context and is included in the <uri> sub-element.

   Each <entry> can contain additional optional information useful to
   the participant when accessing the conference.

   An <entry> element MAY contain the <display-text> sub-element that
   provides a textual description meant for human consumption.

   Each <entry> element SHOULD contain a <purpose> sub-element that
   describes what happens when accessing the URI.  The currently defined
   <purpose> values to be used with the <conf-uris> are:

   participation: Accessing a URI with this <purpose> will bring the
      party into the conference
   streaming: Accessing a URI with this <purpose> will commence
      streaming the conference, but not allow active participation

   Examples of suitable URI schemes include sip: and sips: [8], h323:
   [18], and tel: [17] URIs.  The rtsp [14] URI is suitable for
   streaming.

   Future extensions to this schema may define new values and register
   them with IANA under the registry established by this specification.





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5.2.2  <service-uris>

   This element describes auxiliary services available for the
   conference.  Like <conference-uris>, this element contains a set of
   <entry> child elements - each containing the URI to be used in order
   to access different services available for the particular conference.
   The value of the URI MUST be unique in the conference context and is
   included in the <uri> sub-element.

   An <entry> element MAY contain the <display-text> sub-element that
   provides a textual description meant for user consumption.

   Each <entry> element SHOULD contain a <purpose> sub-element.  The
   currently defined <purpose> values to be used with the <service-uris>
   are:

   web-page: Indicates the web page containing the additional
      information about the conference
   recording: Indicates the link at which the recorded conference
      context can be retrieved
   event: Indicates the URI to which the subscription to the conference
      event package needs to be performed.  This would typically be the
      conference URI of the main conference

   Future extensions to this schema may define new values and register
   them with IANA under the registry established by this specification.

5.2.3  <maximum-user-count>

   This element, if used, specifies the maximum number of users
   permitted in the conference.

5.2.4  <available-media>

   This element contains a sequence of <entry> child elements of
   conference-medium-type, each being indexed by the attribute 'label'.

   The 'label' attribute is the media stream identifier being assigned
   by the conferencing server such as its value is unique in the
   <conference-info> context.  The value of this attribute MAY
   correspond to the SDP "label" media attribute defined in [22].

   Each <entry> describes a single media stream available to the
   participants in the conference and contains the following
   information:






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   <display-text> This element contains the display text for the media
      stream.

   <type> This element contains the media type of the media stream.  The
      value of this element MUST be one of the values registered for
      "media" of SDP [3] and its later revision(s).

   <status> This element indicates the status in both directions of the
      media stream and has the values "sendrecv", "sendonly",
      "recvonly", or "inactive" as defined in SDP [3] and its later
      revision(s).  Note that value specifies the direction from the
      participant's point of view.

5.3  <host-info>

   This element contains information about the entity hosting the
   conference.  This information is set before the conference
   activation, and is rarely changed during the conference lifetime,
   unless the whole conference is moved to be hosted by another entity.
   The host information is comprised of the following elements:

5.3.1  <display-text>

   This element contains display text describing the entity hosting the
   conference.

5.3.2  <web-page>

   This element contains a URI of a web page describing either the
   conference service or the user hosting the conference.

5.3.3  <uris>

   This element can contain additional (to the conference URI) URIs
   pointing to the conference host.

5.4  <conference-state>

   By including this element in the conference document, the server can
   inform the subscribers about the changes in the overall conference
   information.  The <conference-state> child elements are described
   below.

5.4.1  <user-count>

   This element contains the current number of users in the conference.




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5.4.2  <active>

   This Boolean element says whether the conference is currently active
   or not.  A conference is active if dialing into one of the
   <conf-uris> results in successful establishment of a call signaling
   session between the dialed user and the conference focus.

5.4.3  <locked>

   This Boolean element says whether the conference is currently locked
   or not.  In this context, "locked" means that the conference roster
   can not be added to (although participants may leave or be removed
   from the conference).

5.5  <users> of <user>

   The <users> element is a container of <user> child elements, each
   describing a single participant in the conference.

   The following attributes are defined for <user> element:

   entity: This attribute contains the URI for the user in the
      conference.  This is a logical identifier, which corresponds to
      the call signaling authenticated identity of the participant.  The
      'entity' value MUST be unique among all participants in the
      conference.  If for some participants, the focus decides to not
      revealing this information (due to local policies or security
      reasons, for example), the host portion of the user URI MUST use
      the .invalid top level domain (TLD) according to definitions of
      RFC 2606 [5].  The focus also MUST construct the user portion of
      the URI such as the URI is unique among all participants of the
      same domain.  For example,

          "Anonymous1" <sip:anonymous1@anonymous.invalid>

       could be used for a participant requesting privacy in accordance
      with the guidelines for generating anonymous URIs of RFC 3323
      [15].

   state: This attribute indicates whether the document contains the
      whole user information ("full"), only the information that has
      changed since the previous document ("partial"), or the user was
      removed from the conference ("deleted").

   The following child elements are defined for <user> element:






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5.5.1  <display-text>

   This element is used to display the user friendly name in the
   conference.

5.5.2  <associated-aors>

   This element contains associated URIs of the user.  Usually this
   information will be manually provided by a system administrator
   showing the logical association between signaling entities otherwise
   independent.

5.5.3  <roles>

   This element is used to display the roles of the user in the
   conference.

5.5.4  <language>

   This element contains the language preference of the user.  This
   information can be automatically learned via call signaling or be
   manually set per participant.

5.5.5  <cascaded-focus>

   This element contains a conference URI (different from the main
   conference URI) for users that are connected to the main conference
   as a result of focus cascading.  In accordance with the SIP
   conferencing framework [19], this package allows for representation
   of peer-to-peer (i.e.  "flat") focus cascading only.  The actual
   cascading graph can not be deduced from the information provided in
   the package alone.  Advanced applications can construct the graph by
   subscribing to both this package and the Dialog Package [20] of each
   cascaded focus and correlating the relevant information.

5.5.6  <endpoint>

   By including one or more <endpoint> elements under a parent <user>
   element, the server can provide the desired level of details
   (including the state, media streams, and access information) about
   the user's devices and signaling sessions taking part in the
   conference.

   In a conferencing system where authentication is performed per
   endpoint (rather than per user), the focus can be unaware of the
   logical association of multiple endpoints under a common user.  In
   this case, each endpoint will appear as a separate <user> with its
   own <endpoint> sub-element(s) in the conference document.



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   In a different case, the focus may choose to shield the information
   about the participant's multiple endpoints and signaling sessions
   from other subscribers altogether (due to privacy policies, for
   example).  To do so, the focus MAY aggregate the multiple signaling
   sessions' information under a single <endpoint> element.  Note that
   in this case, the detailed call signaling information (represented by
   <call-info> sub-element) will not be included.

5.6  <endpoint>

   This section describes the <endpoint> element in more detail.

   The following attributes are defined for <endpoint> element:

   entity: The server MUST generate the 'entity' key for each <endpoint>
      element included under the parent <user>, such as its value is
      unique in the user context.  In SIP terms, this can be the Contact
      URI, GRUU, etc.

   state: This attribute indicates whether the element contains the
      whole endpoint information ("full"), only the information that has
      changed since the previous document ("partial"), or the endpoint
      has been removed from the conference ("deleted").

   The following child elements are defined for <endpoint> element:

5.6.1  <display-text>

   This element contains the display text for the endpoint.

5.6.2  <referred>

   This element contains information about the user who's action
   resulted in this endpoint being brought into the conference (e.g.
   the SIP user identified by this URI sent a REFER to the focus).  It
   can contain the following sub-elements:

   when: This element contains the date and time that the endpoint was
      referred to the conference and SHOULD be expressed in Coordinated
      Universal Time (UTC) format.

   reason: This element contains the reason the endpoint was referred to
      the conference.

   by: This element contains the URI of the entity who caused the
      endpoint to be referred to the conference.





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5.6.3  <status>

   This element contains the status of the endpoint, and can assume the
   following values:

   connected: The endpoint is a participant in the conference.
      Depending on the media policies, he/she can send and receive media
      to and from other participants.

   disconnected: The endpoint is not a participant in the conference and
      no active dialog exists between the endpoint and the focus.

   on-hold: Active signaling dialog exists between an endpoint and a
      focus, but endpoint is "on-hold" for this conference, i.e.
      neither he/she is "hearing" the conference mix, nor is his/her
      media being mixed in the conference.  As an example, the endpoint
      has asked to join the conference using SIP, but his/her
      participation is pending based on moderator approval.  In the
      meantime he/she is hearing music-on-hold or some other kind of
      related content.

   muted-via-focus: Active signaling dialog exists between an endpoint
      and a focus and the endpoint can "listen" to the conference, but
      endpoint's media is not being mixed into the conference.  Note
      that sometimes a subset of endpoint media streams can be muted by
      focus (such as poor quality video) while others (such as voice or
      IM) can still be active.  In this case, it is RECOMMENDED that the
      "aggregated" endpoint connectivity <status> reflects the status of
      the most active media.

   pending: Endpoint is not yet in the session, but it is anticipated
      that he/she will join in the near future.

   alerting: A PSTN ALERTING or SIP 180 Ringing was returned for the
      outbound call, endpoint is being alerted.

   dialing-in: Endpoint is dialing into the conference, not yet in the
      roster (probably being authenticated).

   dialing-out: Focus has dialed out to connect the endpoint to the
      conference, but the endpoint is not yet in the roster (probably
      being authenticated).

   disconnecting: Focus is in the process of disconnecting the endpoint
      (e.g., in SIP a DISCONNECT or BYE was sent to the endpoint).

   Note that the defined transient statuses (e.g., disconnecting,
   alerting, etc.) could generate a lot of notifications.



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   Implementations MAY choose not to generate notifications on these to
   all participants if it will generate too much traffic.

5.6.4  <joining-method>

   This element contains method by which the endpoint joined the
   conference, and can assume the following values:

   dialed-in: The endpoint dialed into the conference (e.g., in SIP sent
      INVITE to the focus), which resulted in successful dialog
      establishment.

   dialed-out: The focus has brought the endpoint into the conference
      (e.g., in SIP by sending a successful INVITE to the endpoint).

   focus-owner: The endpoint is the focus for this conference.  This
      status is used only when a participant's UA acts as a conference
      focus.

5.6.5  <joining-info>

   This element contains information about how the endpoint joined and
   can contain the following sub-elements:

   when: This element contains the date and time that the endpoint
      joined the conference and SHOULD be expressed in Coordinated
      Universal Time (UTC).

   reason: This element contains the reason the endpoint joined the
      conference.

   by: This element contains the URI of the entity who caused the
      endpoint to join the conference.

5.6.6  <disconnection-method>

   This element contains method by which the endpoint departed the
   conference, and can assume the following values:

   departed: In SIP, the endpoint sent a BYE, thus leaving the
      conference.

   booted: In SIP, the endpoint was sent a BYE by the focus, booting
      him/her out of the conference.  Alternatively, the endpoint tried
      to dial into to conference but was rejected by the focus due to
      local policy.





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   failed: In SIP, the server tried to bring the endpoint into the
      conference, but its attempt to contact the specific endpoint
      resulted in a non-200 class final response.  Alternatively, the
      endpoint tried to dial into the conference without success due to
      technical reasons.

5.6.7  <disconnection-info>

   This element contains information about the endpoint's departure from
   the conference and can contain the following sub-elements:

   when: This element contains the date and time that the endpoint
      departed the conference and SHOULD be expressed in Coordinated
      Universal Time (UTC).

   reason: This element contains the reason the endpoint departed the
      conference.  When known and meaningful, it is RECOMMENDED to
      include the information as conveyed/reported by the call signaling
      in the format defined by RFC 3326 [10].  For example,

   <reason>Reason: SIP ;cause=415 ;text="Unsupported Media Type"</reason>


   by: This element contains the URI of the entity who caused the
      endpoint to depart the conference.

5.6.8  <media>

   This element contains information about a single media stream and is
   included for each media stream being established between the focus
   and the <endpoint>.

   Note that if the <call-info> sub-element of the endpoint is not
   included in the document by the server, it is possible that the media
   streams listed under the common <endpoint> were established by
   separate signaling sessions.

5.6.9  <call-info>

   The <call-info> element provides detailed call signaling information
   for a call being maintained between the participant and the focus.
   Privacy policies MUST be consulted before revealing this information
   to other participants.

   The <sip> sub-element contains the SIP dialog identifier of the
   endpoint's dialog with the focus.  The element includes sub-elements
   <display-text>, <call-id>, <to-tag>, <from-tag>.



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   In future, the <call-info> element can be expanded to include call
   signaling protocol information for other protocols besides SIP.

5.7  <media>

   This section describes the <media> element in more detail.

   A single 'id' attribute is defined for this element.  This is the
   media stream identifier being generated by the server such as its
   value is unique in the endpoint context.  This attribute is the key
   to refer to a particular media stream in the conference document.

   The following child elements are defined for <media>:

5.7.1  <display-text>

   This element contains the display text for the media stream.

5.7.2  <type>

   This element contains the media type for the media stream.  The value
   of this element MUST be one of the values registered for "media" of
   SDP [3] and its later revision(s).

5.7.3  <label>

   The <label> element carries a unique identifier for this stream among
   all streams in the conference and is assigned by the focus.  The
   value of this element corresponds to the SDP "label" media attribute
   defined in [22].

5.7.4  <src-id>

   The <src-id> element, if applicable, carries the information about
   the actual source of the media.  For example, for RTP/RTCP [11] media
   streams, the value MUST contain the SSRC value generated by the
   endpoint for the stream it sends.

   When an RTP mixer generates a CSRC list according to RTP/RTCP [11],
   it inserts a list of the SSRC identifiers of the sources that
   contributed to the generation of a particular packet into the RTP
   header of that packet.  A quote from RFC 3550: "An example
   application is audio conferencing where a mixer indicates all the
   talkers whose speech was combined to produce the outgoing packet,
   allowing the receiver to indicate the current talker, even though all
   the audio packets contain the same SSRC identifier (that of the
   mixer)."




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   If an RTP mixer compliant to the above is used, participants can
   perform an SSRC to user mapping and identify "a current speaker".

5.7.5  <status>

   The element <status> indicates the status in both directions of the
   media stream and has the values "sendrecv", "sendonly", "recvonly",
   or "inactive" as defined in SDP [3] and its later revision(s).  Note
   that value specifies the direction from the participant's point of
   view.  For example, a muted participant's stream will have the value
   of "recvonly".

5.8  <sidebars-by-ref>

   This element contains a set of <entry> child elements each containing
   a sidebar conference URI.  The recipient of the information can then
   subscribe to sidebar information independently from the main
   conference package subscription.

5.9  <sidebar-by-val>

   This element contains a set of <entry> child elements each containing
   information about a single sidebar.  By using this element of
   conference-type, the server can include a full or a partial
   description of each sidebar (as a sub-conference) in the body of the
   main conference document.

6.  XML Schema

   <?xml version="1.0" encoding="UTF-8" ?>
   <xs:schema targetNamespace="urn:ietf:params:xml:ns:conference-info" xmlns:tns="urn:ietf:params:xml:ns:conference-info" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:ietf:params:xml:ns:conference-info" elementFormDefault="qualified" attributeFormDefault="unqualified">
      <!--
             This import brings in the XML language attribute xml:lang
      -->
        <xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/03/xml.xsd" />
      <!--
         CONFERENCE ELEMENT
      -->
      <xs:element name="conference-info" type="conference-type"/>
      <!--
         CONFERENCE TYPE
      -->
      <xs:complexType name="conference-type">



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         <xs:sequence>
               <xs:element name="conference-description" type="conference-description-type" minOccurs="0"/>
           <xs:element name="host-info" type="host-type" minOccurs="0"/>
           <xs:element name="conference-state" type="conference-state-type" minOccurs="0"/>
           <xs:element name="users" type="users-type" minOccurs="0"/>
           <xs:element name="sidebars-by-ref" type="uris-type" minOccurs="0"/>
           <xs:element name="sidebars-by-val" type="sidebars-by-val-type" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:attribute name="entity" type="xs:anyURI" use="required"/>
         <xs:attribute name="state" type="state-type" use="optional" default="full"/>
         <xs:attribute name="version" type="xs:unsignedInt" use="optional"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>
      <!--
         STATE TYPE
      -->
      <xs:simpleType name="state-type">
        <xs:restriction base="xs:string">
                <xs:enumeration value="full"/>
                <xs:enumeration value="partial"/>
                <xs:enumeration value="deleted"/>
        </xs:restriction>
      </xs:simpleType>
      <!--
         CONFERENCE DESCRIPTION TYPE
      -->
      <xs:complexType name="conference-description-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>
           <xs:element name="subject" type="xs:string" minOccurs="0"/>
           <xs:element name="free-text" type="xs:string" minOccurs="0"/>
           <xs:element name="keywords" type="keywords-type" minOccurs="0"/>
           <xs:element name="conf-uris" type="uris-type" minOccurs="0"/>
           <xs:element name="service-uris" type="uris-type" minOccurs="0"/>
           <xs:element name="maximum-user-count" type="xs:unsignedInt" minOccurs="0"/>
           <xs:element name="available-media" type="conference-media-type" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>


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      <!--
         HOST TYPE
      -->
      <xs:complexType name="host-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>
           <xs:element name="web-page" type="xs:anyURI" minOccurs="0"/>
           <xs:element name="uris" type="uris-type" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>
      <!--
         CONFERENCE STATE TYPE
      -->
      <xs:complexType name="conference-state-type">
         <xs:sequence>
               <xs:element name="user-count" type="xs:unsignedInt" minOccurs="0"/>
           <xs:element name="active" type="xs:boolean" minOccurs="0"/>
           <xs:element name="locked" type="xs:boolean" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>
      <!--
         CONFERENCE MEDIA TYPE
      -->
      <xs:complexType name="conference-media-type">
         <xs:sequence>
           <xs:element name="entry" type="conference-medium-type" maxOccurs="unbounded"/>
         </xs:sequence>
      <xs:anyAttribute namespace="##other"/>
      </xs:complexType>
      <!--
         CONFERENCE MEDIUM TYPE
      -->
      <xs:complexType name="conference-medium-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string"/>
           <xs:element name="type" type="xs:string" minOccurs="0"/>
           <xs:element name="status" type="media-status-type" minOccurs="0"/>





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

      <!--
         URIs TYPE
      -->
      <xs:complexType name="uris-type">
         <xs:sequence>
           <xs:element name="entry" type="uri-type" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:attribute name="state" type="state-type" use="optional" default="full"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         URI TYPE
      -->
      <xs:complexType name="uri-type">
         <xs:sequence>
           <xs:element name="uri" type="xs:anyURI"/>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>
           <xs:element name="purpose" type="xs:string" minOccurs="0"/>
           <xs:element name="modified" type="execution-type" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>

         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         KEWORDS TYPE
      -->
      <xs:simpleType name="keywords-type">
             <xs:list itemType="xs:string"/>
      </xs:simpleType>

      <!--
         USERS TYPE
      -->
      <xs:complexType name="users-type">
         <xs:sequence>


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             <xs:element name="user" type="user-type" minOccurs="0" maxOccurs="unbounded"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>

         </xs:sequence>
         <xs:attribute name="state" type="state-type" use="optional" default="full"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>
      <!--
         USER TYPE
      -->
      <xs:complexType name="user-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>
           <xs:element name="associated-aors" type="uris-type" minOccurs="0"/>
           <xs:element name="roles" type="user-roles-type" minOccurs="0"/>
           <xs:element name="language" type="xs:language" minOccurs="0"/>
           <xs:element name="cascaded-focus" type="xs:anyURI" minOccurs="0"/>
           <xs:element name="endpoint" type="endpoint-type" minOccurs="0" maxOccurs="unbounded"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:attribute name="entity" type="xs:anyURI"/>
         <xs:attribute name="state" type="state-type" use="optional" default="full"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         USER ROLES TYPE
      -->
      <xs:complexType name="user-roles-type">
         <xs:sequence>
           <xs:element name="entry" type="xs:string" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         ENDPOINT TYPE
      -->
      <xs:complexType name="endpoint-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>


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           <xs:element name="referred" type="execution-type" minOccurs="0"/>
           <xs:element name="status" type="endpoint-status-type" minOccurs="0"/>
           <xs:element name="joining-method" type="joining-type" minOccurs="0"/>
           <xs:element name="joining-info" type="execution-type" minOccurs="0"/>
           <xs:element name="disconnection-method" type="disconnection-type" minOccurs="0"/>
           <xs:element name="disconnection-info" type="execution-type" minOccurs="0"/>
           <xs:element name="media" type="media-type" minOccurs="0" maxOccurs="unbounded"/>
           <xs:element name="call-info" type="call-type" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:attribute name="entity" type="xs:string"/>
         <xs:attribute name="state" type="state-type" use="optional" default="full"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         ENDPOINT STATUS TYPE
      -->
      <xs:simpleType name="endpoint-status-type">
        <xs:restriction base="xs:string">
                <xs:enumeration value="pending"/>
                <xs:enumeration value="dialing-out"/>
                <xs:enumeration value="dialing-in"/>
                <xs:enumeration value="alerting"/>
                <xs:enumeration value="on-hold"/>
                <xs:enumeration value="connected"/>
                <xs:enumeration value="muted-via-focus"/>
                <xs:enumeration value="disconnecting"/>
                <xs:enumeration value="disconnected"/>
        </xs:restriction>
      </xs:simpleType>
      <!--
         JOINING TYPE
      -->
      <xs:simpleType name="joining-type">
        <xs:restriction base="xs:string">
                <xs:enumeration value="dialed-in"/>
                <xs:enumeration value="dialed-out"/>
                <xs:enumeration value="focus-owner"/>
        </xs:restriction>
      </xs:simpleType>


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      <!--
         DISCONNECTION TYPE
      -->
      <xs:simpleType name="disconnection-type">
             <xs:restriction base="xs:string">
                <xs:enumeration value="departed"/>
                <xs:enumeration value="booted"/>
                <xs:enumeration value="failed"/>
        </xs:restriction>

      </xs:simpleType>

      <!--
         EXECUTION TYPE
      -->
      <xs:complexType name="execution-type">
         <xs:sequence>
           <xs:element name="when" type="xs:dateTime" minOccurs="0"/>
           <xs:element name="reason" type="xs:string" minOccurs="0"/>
           <xs:element name="by" type="xs:anyURI" minOccurs="0"/>
         </xs:sequence>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

     <!--
         CALL TYPE
      -->
      <xs:complexType name="call-type">
         <xs:choice>
           <xs:element name="sip" type="sip-dialog-id-type"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:choice>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         SIP DIALOG ID TYPE
      -->
      <xs:complexType name="sip-dialog-id-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>
           <xs:element name="call-id" type="xs:string"/>
           <xs:element name="from-tag" type="xs:string"/>
           <xs:element name="to-tag" type="xs:string"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>




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         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         MEDIA TYPE
      -->
      <xs:complexType name="media-type">
         <xs:sequence>
           <xs:element name="display-text" type="xs:string" minOccurs="0"/>
           <xs:element name="type" type="xs:string" minOccurs="0"/>
           <xs:element name="label" type="xs:string" minOccurs="0"/>
                 <xs:element name="src-id" type="xs:string" minOccurs="0"/>
           <xs:element name="status" type="media-status-type" minOccurs="0"/>
           <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:attribute name="id" type="xs:string" use="required"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>

      <!--
         MEDIA STATUS TYPE
      -->
      <xs:simpleType name="media-status-type">
        <xs:restriction base="xs:string">
                <xs:enumeration value="recvonly"/>
                <xs:enumeration value="sendonly"/>
                <xs:enumeration value="sendrecv"/>
                <xs:enumeration value="inactive"/>
        </xs:restriction>
      </xs:simpleType>

       <!--
         SIDEBARS BY VAL TYPE
       -->
      <xs:complexType name="sidebars-by-val-type">
         <xs:sequence>
           <xs:element name="entry" type="conference-type" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:attribute name="state" type="state-type" use="optional" default="full"/>
         <xs:anyAttribute namespace="##other"/>
      </xs:complexType>
      </xs:schema>





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7.  Examples

7.1  Basic Example

   The following is an example conference information document:


   <conference-info entity="sips:conf233@example.com" state="partial" version="5" >
   <!--
      CONFERENCE INFO
   -->
      <conference-description>
        <subject>Agenda: This month's goals</subject>
        <service-uris>
                <entry>
                        <uri> http://sharepoint/salesgroup/</uri>
                        <purpose>web-page</purpose>
                </entry>
        </service-uris>
      </conference-description>

   <!--
      CONFERENCE STATE
   -->
      <conference-state>
        <user-count>33</user-count>
      </conference-state>


      <users>
      <!--

          USER
      -->
        <user entity="sip:bob@example.com" state="full">
                <display-text>Bob Hoskins</display-text>
                <!--
                        ENDPOINTS
                -->
                <endpoint entity="sip:bob@pc33.example.com">
                        <display-text>Bob's Laptop</display-text>
                        <status>disconnected</status>
                        <disconnection-method>departed</disconnection-method>
                        <disconnection-info>
                                <when>2005-03-04T20:00:00Z</when>
                                <reason>bad voice quality</reason>
                                <by>sip:mike@example.com</by>
                        </disconnection-info>



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                        <!--
                                MEDIA
                        -->
                        <media id="1">
                                <display-text>main audio</display-text>
                                <type>audio</type>
                                <label>34567</label>
                                <src-id>432424</src-id>

                                <status>sendrecv</status>
                        </media>
                </endpoint>
        </user>

      <!--

        USER
      -->
          <user entity="sip:alice@example.net" state="full">
                        <display-text>Alice</display-text>
                        <!--
                        ENDPOINTS
                -->
                <endpoint entity="sip:4kfk4j392jsu@example.net;grid=433kj4j3u" call="1">

                        <status>connected</status>
                        <joining-method>dialed-out</joining-method>
                        <joining-info>
                                <when>2005-03-04T20:00:00Z</when>
                                <by>sip:mike@example.com</by>
                        </joining-info>
                        <!--
                                MEDIA
                        -->
                        <media id="1">
                                <display-text>main audio</display-text>
                                <type>audio</type>
                                <label>34567</label>
                                <src-id>534232</src-id>
                                <status>sendrecv</status>
                        </media>
                        </endpoint>

          </user>
      </users>

   </conference-info>



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7.2  Rich Example

   The following is an example conference information document.  In this
   example of a partial state notification, there are 32 participants in
   a voice conference.  The user Bob has been booted from the conference
   by Mike due to bad voice quality.  Note that there are three sidebars
   in the conference, two are referenced just by their sidebar URIs and
   information about the third sidebar is included in this notification.
   Also note that while this conference offers both audio and video
   capabilities, only audio is currently in use.


   <conference-info entity="sips:conf233@example.com" state="partial" version="5" >
      <!--
        CONFERENCE INFO
      -->
        <conference-description>
                <display-text>Weekly Sales Meeting</display-text>
                <subject>Agenda: This month's goals</subject>
                <free-text>We will start strict on time</free-text>

                <keywords>sales, meeting, weekly</keywords>
                <conf-uris>
                        <entry>
                                <uri>tel:+18005671234</uri>
                                <display-text>TTI Bridge</display-text>
                                <purpose>participation</purpose>

                        </entry>

                        <entry>
                                <uri>h323:conf545@h323.example.com</uri>
                                <purpose>participation</purpose>
                        </entry>
                        <entry>
        <uri>http://real.streaming.com/54634/live.ram</uri>
                                <purpose>streaming</purpose>
                        </entry>

                </conf-uris>
                <service-uris>
                        <entry>
                                <uri>http://sharepoint/salesgroup/</uri>
                                <purpose>web-page</purpose>
                        </entry>
                        <entry>
        <uri>http://quicktime.com/54634/recording.mov</uri>



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                                <display-text>Quicktime</display-text>

                                <purpose>recording</purpose>
                        </entry>
                </service-uris>
                <maximum-user-count>100</maximum-user-count>
                <available-media>
                        <entry label="34567">
                                <display-text>main audio</display-text>
                                <type>audio</type>
                                <status>sendrecv</status>
                        </entry>
                        <entry label="34569">
                                <display-text>main video</display-text>
                                <type>video</type>
                                <status>inactive</status>
                        </entry>
                </available-media>
        </conference-description>
        <!--

          HOST INFO
        -->
        <host-info>
                <display-text>Sales Host</display-text>
                <web-page>http://sharepoint/salesgroup/hosts/</web-page>
                <uris>
                        <entry>
                                <uri>sip:sales@example.com</uri>
                        </entry>
                </uris>
        </host-info>
        <!--
          CONFERENCE STATE
        -->
        <conference-state>
                <user-count>32</user-count>
                <active>true</active>
                <locked>false</locked>

        </conference-state>

        <!--
        USERS
        -->
        <users>
                <user entity="sip:bob@example.com">
                        <display-text>Bob Hoskins</display-text>



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                        <associated-aors>
                                <entry>
                                        <uri>mailto:bob@example.com</uri>
                                        <display-text>email</display-text>
                                </entry>
                        </associated-aors>
                        <roles>
                                <entry>participant</entry>
                        </roles>
                        <language>en</language>

                <!--
                ENDPOINTS
                -->
                        <endpoint entity="sip:bob@pc33.example.com">
                                <display-text>Bob's Laptop</display-text>
                                <referred>
                                        <when>2005-03-04T20:00:00Z</when>
                                        <reason>expert required</reason>
                                        <by>sip:mike@example.com</by>
                                </referred>
                                <status>disconnecting</status>
                                <joining-method>dialed-out</joining-method>
                                <joining-info>

                                        <when>2005-03-04T20:00:00Z</when>
                                        <reason>invitation</reason>
                                        <by>sip:mike@example.com</by>

                                </joining-info>
                                <disconnection-method>booted</disconnection-method>
                                <disconnection-info>
                                        <when>2005-03-04T20:00:00Z</when>
                                        <reason>bad voice quality</reason>
                                        <by>sip:mike@example.com</by>
                                </disconnection-info>
                        <!--
                        CALL INFO
                        -->
                                <call-info>
                                        <sip>
                                           <display-text>full info</display-text>
                                           <call-id>hsjh8980vhsb78</call-id>
                                           <from-tag>vav738dvbs</from-tag>
                                           <to-tag>8954jgjg8432</to-tag>
                                        </sip>
                                </call-info>
                        <!--



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                        MEDIA
                        -->
                                <media id="1">
                                        <display-text>main audio</display-text>
                                        <type>audio</type>
                                        <label>34567</label>
                                        <src-id>432424</src-id>
                                        <status>sendrecv</status>
                                </media>
                        </endpoint>
                </user>
        </users>

        <!--
        SIDEBARS BY REFERENCE
        -->
        <sidebars-by-ref state="partial">
                <entry>
                        <uri>sips:conf233@example.com; grid=45</uri>
                        <display-text>sidebar with Carol</display-text>
                </entry>
                <entry>
                        <uri>sips:conf233@example.com; grid=21</uri>
                        <display-text>private sidebar with Peter</display-text>
                </entry>
        </sidebars-by-ref>

        <!--
        SIDEBARS BY VALUE
        -->
        <sidebars-by-val state="partial">
                <entry entity="sips:conf233@example.com; grid=77" state="partial">

                        <users>
                                <user entity="sip:bob@example.com"></user>
                                <user entity="sip:mark@example.com"></user>
                                <user entity="sip:dan@example.com"></user>
                        </users>
                </entry>
        </sidebars-by-val>

   </conference-info>


8.  Security Considerations

   Subscriptions to conference state can reveal very sensitive
   information.  For this reason, the document recommends authentication



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   and authorization, and provides guidelines on sensible authorization
   policies.

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

   Since a focus provides participant identity information using this
   event package, participant privacy needs to be taken into account.  A
   focus MUST support requests by participants for privacy.  Privacy can
   be indicated by the conference policy - for every participant or
   select participants.  It can also be indicated in the session
   signaling.  In SIP this can be done using the Privacy header field
   described in RFC 3323 [15].  For a participant requesting privacy, no
   identity information SHOULD be revealed by the focus such as a URI
   (e.g.  the Address of Record, Contact, or GRUU).  For these cases,
   the anonymous URI generation method outlined in section Section 5.5
   of this document MUST be followed.

9.  IANA Considerations

   This document registers a SIP event package, a new MIME type,
   application/conference-info+xml, a new XML namespace, a new XML
   schema, and creates a  sub-registry "URI purposes" under the
   existing registry: http://www.iana.org/assignments/sip-parameters.

9.1  conference Event Package Registration

   This specification registers an event package, based on the
   registration procedures defined in RFC 3265 [9].  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, jdrosen@jdrosen.net.

9.2  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 [7]
   Encoding considerations: Same as encoding considerations of
      application/xml as specified in RFC 3023 [7]
   Security considerations: See Section 10 of RFC 3023 [7] and Section 8
      of this specification





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   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, <jdrosen@jdrosen.net>
   Intended usage: COMMON
   Author/Change controller: The IETF

9.3  URN Sub-Namespace Registration for
    urn:ietf:params:xml:ns:conference-info

   This section registers a new XML namespace, as per the guidelines in
   RFC 3688 [13].

   URI: The URI for this namespace is
      urn:ietf:params:xml:ns:conference-info
   Registrant Contact: IETF, SIPPING working group, <sipping@ietf.org>,
      Jonathan Rosenberg <jdrosen@jdrosen.net>
   XML:


   BEGIN
   <?xml version="1.0"?>
   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
             "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
   <html xmlns="http://www.w3.org/1999/xhtml">
   <head>
     <meta http-equiv="content-type"
        content="text/html;charset=iso-8859-1"/>
     <title>Conference Information Namespace</title>

   </head
   <body>
     <h1>Namespace for Conference Information</h1>
     <h2>urn:ietf:params:xml:ns:conference-info</h2>
     <p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
   </body>
   </html>
   END







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9.4  XML Schema Registration

   This specification registers a schema, as per the guidelines in RFC
   3688 [13].
      URI: please assign
      Registrant Contact: IETF, SIPPING Working Group
      (sipping@ietf.org), Jonathan Rosenberg (jdrosen@jdrosen.net)
      XML: The XML can be found as the sole content of Section 6

9.5  URI Purposes Sub-registry Establishment

   This document instructs the IANA to create a new sub-registry "URI
   purposes" under the already existing registry:
   http://www.iana.org/assignments/sip-parameters.

   The purpose of a URI is an XML element, encoded in the conference
   event package [RFC XXXX - substitute with the number assigned to this
   draft].  The value of the <purpose> element indicates the intended
   usage of the URI in the context of the conference event package and
   is defined in sections Section 5.2.1 and Section 5.2.2 of this
   specification.

   This sub-registry is defined as a table that contains the following
   three columns:

   Value: The token under registration
   Description: A descriptive text defining the intended usage of the
      URI
   Document: A reference to the document defining the registration

   This specification instructs IANA to create the table with the
   initial content as defined below:



















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   Value         Description                         Document
   -------       ----------------------------------  ----------

   participation The URI can be used to join the     [RFC XXXX]
                 conference

   streaming     The URI can be used to access the   [RFC XXXX]
                 streamed conference data

   event         The URI can be used to subscribe    [RFC XXXX]
                 to the conference event package

   recording     The URI can be used to access the   [RFC XXXX]
                 recorded conference data

   web-page      The URI can be used to access a     [RFC XXXX]
                 web page that contains additional
                 information of the conference


   New values of the "URI purposes" are registered by the IANA when a
   specification becomes available and according to the definition of
   RFC 2434 [4].  The IANA Considerations section of the specification
   MUST include the following information:

   Value: The value of the <purpose> element to be registered
   Description: A short description of the intended usage of the URI

10.  Acknowledgements

   The authors would like to thank Dan Petrie, Sean Olson, Alan
   Johnston, Rohan Mahy, Cullen Jennings, Brian Rosen, Roni Even, and
   Miguel Garcia for their comments and inputs.

11.  References

11.1  Normative References

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

   [2]   Moats, R., "URN Syntax", RFC 2141, May 1997.

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

   [4]   Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
         Considerations Section in RFCs", BCP 26, RFC 2434, October



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         1998.

   [5]   Eastlake, D. and A. Panitz, "Reserved Top Level DNS Names",
         BCP 32, RFC 2606, June 1999.

   [6]   Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
         August 1999.

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

   [8]   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.

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

   [10]  Schulzrinne, H., Oran, D. and G. Camarillo, "The Reason Header
         Field for the Session Initiation Protocol (SIP)", RFC 3326,
         December 2002.

   [11]  Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson,
         "RTP: A Transport Protocol for Real-Time Applications", STD 64,
         RFC 3550, July 2003.

   [12]  Yergeau, F., "UTF-8, a transformation format of ISO 10646",
         STD 63, RFC 3629, November 2003.

   [13]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
         January 2004.

11.2  Informative References

   [14]  Schulzrinne, H., Rao, A. and R. Lanphier, "Real Time Streaming
         Protocol (RTSP)", RFC 2326, April 1998.

   [15]  Peterson, J., "A Privacy Mechanism for the Session Initiation
         Protocol (SIP)", RFC 3323, November 2002.

   [16]  Camarillo, G., Eriksson, G., Holler, J. and H. Schulzrinne,
         "Grouping of Media Lines in the Session Description Protocol
         (SDP)", RFC 3388, December 2002.

   [17]  Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966,
         December 2004.

   [18]  Levin, O., "H.323 Uniform Resource Locator (URL) Scheme



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         Registration", RFC 3508, April 2003.

   [19]  Rosenberg, J., "A Framework for Conferencing with the Session
         Initiation Protocol",
         Internet-Draft draft-ietf-sipping-conferencing-framework-04,
         February 2005.

   [20]  Rosenberg, J., "An INVITE Inititiated Dialog Event Package for
         the Session Initiation  Protocol (SIP)",
         Internet-Draft draft-ietf-sipping-dialog-package-05, November
         2004.

   [21]  Rosenberg, J., "Obtaining and Using Globally Routable User
         Agent (UA) URIs (GRUU) in the  Session Initiation Protocol
         (SIP)", Internet-Draft draft-ietf-sip-gruu-03, February 2005.

   [22]  Levin, O. and G. Camarillo, "The SDP (Session Description
         Protocol) Label Attribute",
         Internet-Draft draft-ietf-mmusic-sdp-media-label-01, January
         2005.


Authors' Addresses

   Jonathan Rosenberg
   Cisco Systems
   600 Lanidex Plaza
   Parsippany, NJ  07054
   US

   Phone: +1 973 952-5000
   Email: jdrosen@cisco.com
   URI:   http://www.jdrosen.net


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

   Email: schulzrinne@cs.columbia.edu
   URI:   http://www.cs.columbia.edu/~hgs







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   Orit Levin (editor)
   Microsoft Corporation
   One Microsoft Way
   Redmond, WA  98052
   US

   Email: oritl@microsoft.com












































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Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
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   Copies of IPR disclosures made to the IETF Secretariat and any
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   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
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Rosenberg, et al.      Expires September 26, 2005              [Page 43]


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