SIPPING J. Rosenberg Internet-Draft Cisco Systems Expires: June 6, 2005 H. Schulzrinne Columbia University O. Levin, Ed. Microsoft Corporation December 6, 2004 A Session Initiation Protocol (SIP) Event Package for Conference State draft-ietf-sipping-conference-package-08 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 Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 6, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document defines a conference event package for the Session Initiation Protocol (SIP) Events framework, along with a data format used in notifications for this package. The conference package Rosenberg, et al. Expires June 6, 2005 [Page 1] Internet-Draft Conference Package December 2004 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 . . . . . . . . . . . . . . . . . . . . 5 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 . . . . . . . . . . . . . . . . . . . . . . . . 8 4.4 State and Partial Notifications . . . . . . . . . . . . . 8 4.5 Element Keys . . . . . . . . . . . . . . . . . . . . . . . 8 4.6 Constructing Coherent State Procedure . . . . . . . . . . 9 5. Conference Data . . . . . . . . . . . . . . . . . . . . . . . 10 5.1 conference-type . . . . . . . . . . . . . . . . . . . . . 10 5.1.1 conference-description of conference-description-type . . . . . . . . . . . . . 11 5.1.2 host-info of host-type . . . . . . . . . . . . . . . . 11 5.1.3 conference-state of conference-state-type . . . . . . 11 5.1.4 users of users-type . . . . . . . . . . . . . . . . . 11 5.1.5 sidebars-by-ref of uris-type . . . . . . . . . . . . . 11 5.1.6 sidebar-by-val of conference-type . . . . . . . . . . 11 5.2 conference-description-type . . . . . . . . . . . . . . . 12 5.2.1 display-text of string type . . . . . . . . . . . . . 12 5.2.2 subject of string type . . . . . . . . . . . . . . . . 12 5.2.3 free-text of string type . . . . . . . . . . . . . . . 12 5.2.4 keywords of keywords-type . . . . . . . . . . . . . . 12 5.2.5 conf-uris of uris-type . . . . . . . . . . . . . . . . 12 5.2.6 service-uris of uris-type . . . . . . . . . . . . . . 13 5.2.7 maximum-user-count of user-count-type . . . . . . . . 13 5.2.8 available-media of conference-medias-type . . . . . . 13 5.3 host-type . . . . . . . . . . . . . . . . . . . . . . . . 13 5.3.1 display-text of string type . . . . . . . . . . . . . 14 5.3.2 web-page of anyURI type . . . . . . . . . . . . . . . 14 Rosenberg, et al. Expires June 6, 2005 [Page 2] Internet-Draft Conference Package December 2004 5.3.3 uris of uris-type . . . . . . . . . . . . . . . . . . 14 5.4 conference-state-type . . . . . . . . . . . . . . . . . . 14 5.4.1 user-count of user-count-type . . . . . . . . . . . . 14 5.4.2 active of Boolean type . . . . . . . . . . . . . . . . 14 5.4.3 locked of Boolean type . . . . . . . . . . . . . . . . 14 5.4.4 active-media of conference-medias-type . . . . . . . . 14 5.5 user-type . . . . . . . . . . . . . . . . . . . . . . . . 15 5.5.1 display-text of string type . . . . . . . . . . . . . 15 5.5.2 associated-aors of anyURI type . . . . . . . . . . . . 15 5.5.3 roles of user-roles-type . . . . . . . . . . . . . . . 15 5.5.4 language of language type . . . . . . . . . . . . . . 15 5.5.5 cascaded-focus of anyURI type . . . . . . . . . . . . 16 5.5.6 endpoint of endpoint-type . . . . . . . . . . . . . . 16 5.6 endpoint-type . . . . . . . . . . . . . . . . . . . . . . 16 5.6.1 display-text of string type . . . . . . . . . . . . . 17 5.6.2 referred of execution-type . . . . . . . . . . . . . . 17 5.6.3 status of endpoint-status-type . . . . . . . . . . . . 17 5.6.4 joining-method of joining-type . . . . . . . . . . . . 18 5.6.5 joining-info of execution-type . . . . . . . . . . . . 19 5.6.6 disconnection-method of disconnection-type . . . . . . 19 5.6.7 disconnection-info of execution-type . . . . . . . . . 19 5.6.8 media of media-type . . . . . . . . . . . . . . . . . 20 5.7 media-type . . . . . . . . . . . . . . . . . . . . . . . . 20 5.7.1 display-text of string type . . . . . . . . . . . . . 20 5.7.2 proto of string type . . . . . . . . . . . . . . . . . 20 5.7.3 src-id of string type . . . . . . . . . . . . . . . . 20 5.7.4 label of string type . . . . . . . . . . . . . . . . . 21 5.7.5 status of media-status-type . . . . . . . . . . . . . 21 5.7.6 call of call-type . . . . . . . . . . . . . . . . . . 21 6. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 22 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 7.1 Basic Example . . . . . . . . . . . . . . . . . . . . . . 29 7.2 Rich Example . . . . . . . . . . . . . . . . . . . . . . . 31 8. Security Considerations . . . . . . . . . . . . . . . . . . . 36 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 Rosenberg, et al. Expires June 6, 2005 [Page 3] Internet-Draft Conference Package December 2004 1. Introduction The Session Initiation Protocol (SIP) [7] Events framework Events Framework [8] 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 [18]. 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 [18]. The focus has sufficient information about the state of the conference to inform subscribers about it. It is possible 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 element as specified by this package. This section provides the details for defining a SIP-specific event notification package, as specified by RFC 3265 [8]. Rosenberg, et al. Expires June 6, 2005 [Page 4] Internet-Draft Conference Package December 2004 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 RFC 3265 [8]. 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" RFC 3265 [8]. 3.4 NOTIFY Bodies As described in RFC 3265 [8], 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. Rosenberg, et al. Expires June 6, 2005 [Page 5] Internet-Draft Conference Package December 2004 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. 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. 3.6 Notifier Generation of NOTIFY Requests Notifications MUST 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; Rosenberg, et al. Expires June 6, 2005 [Page 6] Internet-Draft Conference Package December 2004 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 4.6 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 not 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 SHOULD be valid. It MUST be based on Extensible Markup Language (XML) 1.0 and MUST be encoded using UTF-8 [13]. 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 [5] and extended by RFC 3688 [14]. This URN is: urn:ietf:params:xml:ns:conference-info Rosenberg, et al. Expires June 6, 2005 [Page 7] Internet-Draft Conference Package December 2004 4.3 Versioning The conference information is described by a hierarchal XML structure with the root element . The root element is the 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 optional 'version' attribute MUST be included in the root element. 4.4 State and Partial Notifications All sub-elements in the hierarchal XML structure can be classified in two groups: those that carry relatively small amount of data and those that can potentially carry a lot of data. During partial notifications, the light elements are updated as atomic pieces of data. On the other hand, elements that can carry a substantial amount of data have the general 'state' attribute attached to them. That is in order to support partial notifications for their content. The 'state' attribute 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". 4.5 Element Keys In the context of this specification, the element key is the set of mandatory attributes or sub-elements of the element. The key value MUST be unique for the element among its siblings of the same type. In a partial notification event it must be possible to uniquely identify each sub-element among others of the same type under a common parent element. In order to achieve this property, all sub-elements, with possible multiple appearances under a common parent (which has the attribute 'state') have keys defined to them. Below is the list of the elements with their keys as defined by this specification: Rosenberg, et al. Expires June 6, 2005 [Page 8] Internet-Draft Conference Package December 2004 o Elements , , and use as the key 'entity' o Element uses as the key 'id' o Sub-element of uris-type contained in elements and uses as the key o Elements and of conference-medias-type use as the key o Elements and of count-type use as the key o Element of user-roles-type uses as the key o Sub-element of conference-type contained in element uses as the key 'entity' o Elements and of uris-type use as the key 4.6 Constructing Coherent State Procedure A Conference package subscriber MUST initialize the 'version' attribute from the element with the value in the first document received. The conference package subscriber locally maintains a local element for each element in the schema and a table for each element with key(s) in the schema and indexed by these key(s). 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 less than the local version, the document is discarded without processing. If the value in the document is higher than the local version number, the local version number is set to the value in the new document and the document is processed. If the value in the received document is more than one higher than the previous local version number and the document contained a partial state, the subscriber SHOULD generate a refresh request to trigger a full state notification. Further processing of the conference information depends on the state contained in the received conference document and indicated by the value of the 'state' attribute in the element. If it contains "full" state, the whole local content is flushed and repopulated from the document. If it contains "deleted" state, it means that the conference ceased to exist and the subscriber SHOULD terminate the subscription by sending the SUBSCRIBE with Expires = 0. If the document contains "partial" state, the document is used to update the local content as described below. Starting from outer elements in the received document, Rosenberg, et al. Expires June 6, 2005 [Page 9] Internet-Draft Conference Package December 2004 1. If the parent element contains "full" state, the whole local element content is flushed and repopulated from the document. 2. Otherwise, if the parent element contains "deleted" state, the whole element MUST be removed from the local content. 3. Otherwise, if the parent 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 2.2. 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. 5. Conference Data A conference information document begins with the root element tag of conference-type. Sections below describe the complex types composing the hierarchal conference-type. The full XML schema is defined in Section 6. 5.1 conference-type This type defines the following attributes: 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 details see Section 4. Rosenberg, et al. Expires June 6, 2005 [Page 10] Internet-Draft Conference Package December 2004 version: This attribute allows the recipient of conference information documents to properly order them and it MUST be included when used in the root element. Versions start at 0 and increment by one for each new document sent to a subscriber. Versions are scoped within a subscription. Versions are represented using a 32 bit integer. The conference-type defines an extendable sequence of child elements. A "full" conference document MUST at least include the following sub-elements: , , and . The child elements are described in details below: 5.1.1 conference-description of conference-description-type This element contains conference information that is derived from system conference policies, is set before the conference activation, and is rarely changed during the conference lifetime. 5.1.2 host-info of host-type This element contains information about the entity that hosts 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. 5.1.3 conference-state of conference-state-type This element contains the dynamic information about the current state of the conference. 5.1.4 users of users-type This element can contain an unbounded number of sub-elements of user-type each containing the information about a participant in the conference. 5.1.5 sidebars-by-ref of uris-type This element contains sub-elements of uri-type which provide pointers to sidebar information through sidebar URIs. The recipient of the information can then subscribe to sidebar information independently from the main conference package subscription. 5.1.6 sidebar-by-val of conference-type This element provides sidebar information as a part of the main Rosenberg, et al. Expires June 6, 2005 [Page 11] Internet-Draft Conference Package December 2004 conference package information. 5.2 conference-description-type This type defines the 'state' attribute which can contain the values "full", "partial", or "deleted". This type defines an extendable sequence of the following child elements: 5.2.1 display-text of string type This element contains text description of the conference. 5.2.2 subject of string type This element contains the subject of the conference. 5.2.3 free-text of string type This element contains free form text about the conference. 5.2.4 keywords of keywords-type This element contains a list of words that can be used by automatic search engines to better classify the conference. 5.2.5 conf-uris of uris-type This element contains a set of sub-elements - each containing the information about an additional conference URI that this conference can be accessed by. The value of the URI is included in the sub-element and its description MAY be included in the sub-element. The purpose of the URI SHOULD be included in the sub-element. The currently defined values to be used with the are: participation: Indicates that dialing into this URI will bring the party into the conference streaming: Indicates that "listening" to this URI will provide the conference live content Future extensions to this schema may define new values and register them with IANA under the registry established by this specification. Examples of such URIs include sip: / sips: [7], h323: [17], and tel: Rosenberg, et al. Expires June 6, 2005 [Page 12] Internet-Draft Conference Package December 2004 [16] URIs. 5.2.6 service-uris of uris-type This element contains a set of sub-elements - each containing the URI to be used in order to access different services available for the particular conference. The value of the URI is included in the sub-element and its description MAY be included in the sub-element. The purpose of the URI SHOULD be included in the sub-element. The currently defined values to be used with the 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 Future extensions to this schema may define new values and register them with IANA under the registry established by this specification. 5.2.7 maximum-user-count of user-count-type This element is used to specify the maximum number of users permitted in the conference. The number SHOULD be provided for all participants in total by populating the sub-element with value "any". Additionally counters for users with certain roles in the conference MAY be separately provided. 5.2.8 available-media of conference-medias-type This element contains information about the media types available in the conference. The sub-element MUST contain one of the values registered for "proto" of SDP [3] and its later revision(s). 5.3 host-type This type defines the 'state' attribute which can contain the values "full", "partial", or "deleted". This type defines an extendable sequence of the following child elements: Rosenberg, et al. Expires June 6, 2005 [Page 13] Internet-Draft Conference Package December 2004 5.3.1 display-text of string type This element contains display text information about the entity hosting the conference. 5.3.2 web-page of anyURI type This element contains a web page URI about the user hosting the conference. 5.3.3 uris of uris-type The sub-element contains additional URIs pointing to the conference host. 5.4 conference-state-type This type defines the 'state' attribute which can contain the values "full", "partial", or "deleted". This type defines an extendable sequence of the following child elements. 5.4.1 user-count of user-count-type This element is used to specify the current number of users in the conference. The number SHOULD be provided for all participants in total by populating the sub-element with value "any". Additionally counters for users with certain roles in the conference MAY be separately provided. 5.4.2 active of Boolean type This element says whether the conference is currently active or not. For example, a conference can be scheduled for a certain start time and its conference URI reserved and published. Still, the conference will not be "active" till its actual start time. 5.4.3 locked of Boolean type This element contains information about whether the conference is currently locked. In this context, "locked" means that the conference roster can not be added to (although participants may leave or be removed from the conference). 5.4.4 active-media of conference-medias-type This element contains information about the media types currently Rosenberg, et al. Expires June 6, 2005 [Page 14] Internet-Draft Conference Package December 2004 active in the conference, which is a subset of those listed in the element. 5.5 user-type This type defines the following attributes: entity: This attribute contains the URI for the user in the conference. This is a logical identifier, which corresponds to the authenticated identity of the participant. The 'entity' attribute MUST be unique in the user element list because it is used as the key in partial notifications about users' state. An anonymous participant in a conference SHOULD be represented by an anonymous URI generated by the focus. For multiple anonymous participants, the focus must ensure that each anonymous URI is unique. The guidelines for generating anonymous URIs in RFC 3323 [9] should be followed. For example, "Anonymous1" could be used for a participant requesting privacy. 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"). This type defines an extendable sequence of the following child elements. 5.5.1 display-text of string type This element contains the display text for the user. 5.5.2 associated-aors of anyURI type 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 of user-roles-type This element contains the roles of the user. 5.5.4 language of language type This element contains the language preference of the user. This Rosenberg, et al. Expires June 6, 2005 [Page 15] Internet-Draft Conference Package December 2004 information can be automatically learned via call signaling or be manually set per participant. 5.5.5 cascaded-focus of anyURI type 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 [18], 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 [19] of the cascaded foci and correlating the relevant information. 5.5.6 endpoint of endpoint-type This element contains information about an endpoint of the user. The element of the endpoint-type can have unbounded number of appearance in the user-type for each endpoint of the user participating in the conference. In a case when authentication is performed per endpoint (rather than per user) in a system, a focus can be not aware of the logical association among endpoints being used by the same user. In this case the focus MAY present the endpoints as belonging to separate users in the conference schema. In a different case, due to privacy concerns for a user, the focus may want to shield the information about multiple endpoints from the recipients of the Conference document. To do so the focus MAY aggregate the multiple endpoint information into a single endpoint element under this user. 5.6 endpoint-type This type defines the following attributes: entity: The attribute contains the endpoint URI for the user in the conference. In SIP terms, this is the Contact URI or GRUU. The 'entity' attribute MUST be unique in the endpoint element list because it is used as the key in partial notifications about users' endpoints. An endpoint belonging to an anonymous participant in a conference SHOULD be represented by an anonymous URI generated by the focus. For multiple anonymous endpoints, the focus must ensure that each anonymous URI is unique. The guidelines for generating anonymous URIs in RFC 3323 [9] should be followed. Rosenberg, et al. Expires June 6, 2005 [Page 16] Internet-Draft Conference Package December 2004 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 deleted from the conference ("deleted"). This type defines an extendable sequence of the following child elements. 5.6.1 display-text of string type This element contains the display text for the endpoint. 5.6.2 referred of execution-type 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. 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. 5.6.3 status of endpoint-status-type 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 SIP 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. Rosenberg, et al. Expires June 6, 2005 [Page 17] Internet-Draft Conference Package December 2004 muted-via-focus: Active SIP 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 reflects the status of the mostly 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 endpoint (either DISCONNECT or BYE was sent to the endpoint). Note that the defined transient statuss (e.g., disconnecting, alerting, etc.) could generate a lot of notifications. Implementations MAY choose not to generate notifications on these to all participants if it will generate too much traffic. 5.6.4 joining-method of joining-type 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, i.e. sent INVITE to the focus, which resulted in successful dialog establishment. dialed-out: The focus has brought the endpoint into the conference 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 participantĘs UA acts as a conference focus. Rosenberg, et al. Expires June 6, 2005 [Page 18] Internet-Draft Conference Package December 2004 5.6.5 joining-info of execution-type 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. 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 of disconnection-type This element contains method by which the endpoint departed the conference, and can assume the following values: departed: The endpoint sent a BYE, thus leaving the conference. booted: 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 without success because was rejected by the focus according to local policy decisions. failed: 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 of execution-type 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. 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: SIP ;cause=415 ;text="Unsupported Media Type" Rosenberg, et al. Expires June 6, 2005 [Page 19] Internet-Draft Conference Package December 2004 by: This element contains the URI of the entity who caused the endpoint to depart the conference. 5.6.8 media of media-type This element contains information about a media stream of this endpoint. The element of the media-type can have an unbounded number of appearances in the endpoint-type for each media stream of the endpoint. Note that it is possible that media streams listed under a common endpoint MAY be established by separate signaling means and consequently belong to different signaling "calls". 5.7 media-type This type defines the following attributes: id: The attribute is a unique identifier of a media stream on a per endpoint basis. This attribute is used as a key to identify media streams which may be added and deleted on a dynamic basis during the conference. If the SDP "mid" (as defined in Grouping of Media Lines in the SDP [11]) is used for establishing the media stream, the 'id' SHOULD contain the same "mid" value, otherwise the notification service MUST generate an 'id' value which is unique in the endpoint context. state: This attribute indicates whether the element contains the whole media information ("full"), only the information that has changed since the previous notification ("partial"), or that the media element has been deleted from the conference document ("deleted"). This type defines an extendable sequence of the following child elements. 5.7.1 display-text of string type This element contains the display text for the media stream. 5.7.2 proto of string type This element contains the media type for the media stream. The value of this element MUST be one of the values registered for "proto" of SDP [3] and its later revision(s). 5.7.3 src-id of string type The element, if applicable, carries the information about Rosenberg, et al. Expires June 6, 2005 [Page 20] Internet-Draft Conference Package December 2004 the actual source of the media. For example, for the RTP/RTCP [12] 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 [12], 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)." If an RTP mixer compliant to the above is used, participants can perform an SSRC to user mapping and identify "a current speaker". 5.7.4 label of string type The element