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 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 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 Rosenberg, et al. Expires September 26, 2005 [Page 1] Internet-Draft Conference Package March 2005 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 . . . . . . . . . . . . . . . . . . . . 11 5.2 . . . . . . . . . . . . . . . . . 11 5.2.1 . . . . . . . . . . . . . . . . . . . . . 12 5.2.2 . . . . . . . . . . . . . . . . . . . . 13 5.2.3 . . . . . . . . . . . . . . . . . 13 5.2.4 . . . . . . . . . . . . . . . . . . 13 5.3 . . . . . . . . . . . . . . . . . . . . . . . 14 5.3.1 . . . . . . . . . . . . . . . . . . . . 14 5.3.2 . . . . . . . . . . . . . . . . . . . . . . 14 5.3.3 . . . . . . . . . . . . . . . . . . . . . . . . 14 5.4 . . . . . . . . . . . . . . . . . . . . 14 5.4.1 . . . . . . . . . . . . . . . . . . . . . 14 5.4.2 . . . . . . . . . . . . . . . . . . . . . . . 15 5.4.3 . . . . . . . . . . . . . . . . . . . . . . . 15 5.5 of . . . . . . . . . . . . . . . . . . . . 15 5.5.1 . . . . . . . . . . . . . . . . . . . . 16 5.5.2 . . . . . . . . . . . . . . . . . . 16 5.5.3 . . . . . . . . . . . . . . . . . . . . . . . 16 5.5.4 . . . . . . . . . . . . . . . . . . . . . . 16 Rosenberg, et al. Expires September 26, 2005 [Page 2] Internet-Draft Conference Package March 2005 5.5.5 . . . . . . . . . . . . . . . . . . . 16 5.5.6 . . . . . . . . . . . . . . . . . . . . . . 16 5.6 . . . . . . . . . . . . . . . . . . . . . . . . 17 5.6.1 . . . . . . . . . . . . . . . . . . . . 17 5.6.2 . . . . . . . . . . . . . . . . . . . . . . 17 5.6.3 . . . . . . . . . . . . . . . . . . . . . . . 18 5.6.4 . . . . . . . . . . . . . . . . . . . 19 5.6.5 . . . . . . . . . . . . . . . . . . . . 19 5.6.6 . . . . . . . . . . . . . . . . 19 5.6.7 . . . . . . . . . . . . . . . . . 20 5.6.8 . . . . . . . . . . . . . . . . . . . . . . . 20 5.6.9 . . . . . . . . . . . . . . . . . . . . . 20 5.7 . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.7.1 . . . . . . . . . . . . . . . . . . . . 21 5.7.2 . . . . . . . . . . . . . . . . . . . . . . . . 21 5.7.3 . . . . . . . . . . . . . . . . . . . . . . . 21 5.7.4 . . . . . . . . . . . . . . . . . . . . . . . 21 5.7.5 . . . . . . . . . . . . . . . . . . . . . . . 22 5.8 . . . . . . . . . . . . . . . . . . . . 22 5.9 . . . . . . . . . . . . . . . . . . . . . 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 Rosenberg, et al. Expires September 26, 2005 [Page 3] Internet-Draft Conference Package March 2005 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 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 Rosenberg, et al. Expires September 26, 2005 [Page 4] Internet-Draft Conference Package March 2005 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. Rosenberg, et al. Expires September 26, 2005 [Page 5] Internet-Draft Conference Package March 2005 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 Rosenberg, et al. Expires September 26, 2005 [Page 6] Internet-Draft Conference Package March 2005 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 . The root element is the Rosenberg, et al. Expires September 26, 2005 [Page 7] Internet-Draft Conference Package March 2005 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 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 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 o Element o Element o Element o Element o Element 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". Rosenberg, et al. Expires September 26, 2005 [Page 8] Internet-Draft Conference Package March 2005 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 uses as the key 'entity' o Element uses as the key 'entity' o Element uses as the key 'id' o Element (child to ) uses as the key 'entity' o Element uses as the key 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 element), the conference package subscriber MUST set the local 'version' number to the value of the 'version' attribute from the received 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 Rosenberg, et al. Expires September 26, 2005 [Page 9] Internet-Draft Conference Package March 2005 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 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 Rosenberg, et al. Expires September 26, 2005 [Page 10] Internet-Draft Conference Package March 2005 5.1 A conference information document begins with the root element tag of conference-type. The following attributes are defined for : 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 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 element is comprised of , , , , and child elements. A "full" conference document MUST at least include the and child elements. Following sections describe these elements in detail. The full XML schema is provided in Section 6. 5.2 The element describes the conference as a whole. The child elements , , , and are used to describe the conference content: : Contains a text suitable for human consumption and directory listing : Contains the subject of the conference Rosenberg, et al. Expires September 26, 2005 [Page 11] Internet-Draft Conference Package March 2005 : Contains an additional longer description of the conference : Contains a list of comma-separated keywords that can be used by search engines to better classify the conference Additional child elements and are used to describe the conference-related URIs; and 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 in the future. 5.2.1 This element is a set of 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 sub-element. Each can contain additional optional information useful to the participant when accessing the conference. An element MAY contain the sub-element that provides a textual description meant for human consumption. Each element SHOULD contain a sub-element that describes what happens when accessing the URI. The currently defined values to be used with the are: participation: Accessing a URI with this will bring the party into the conference streaming: Accessing a URI with this 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. Rosenberg, et al. Expires September 26, 2005 [Page 12] Internet-Draft Conference Package March 2005 5.2.2 This element describes auxiliary services available for the conference. Like , this element contains a set of 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 sub-element. An element MAY contain the sub-element that provides a textual description meant for user consumption. Each element SHOULD contain a 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. 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 This element, if used, specifies the maximum number of users permitted in the conference. 5.2.4 This element contains a sequence of 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 context. The value of this attribute MAY correspond to the SDP "label" media attribute defined in [22]. Each describes a single media stream available to the participants in the conference and contains the following information: Rosenberg, et al. Expires September 26, 2005 [Page 13] Internet-Draft Conference Package March 2005 This element contains the display text for the media stream. 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). 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 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 This element contains display text describing the entity hosting the conference. 5.3.2 This element contains a URI of a web page describing either the conference service or the user hosting the conference. 5.3.3 This element can contain additional (to the conference URI) URIs pointing to the conference host. 5.4 By including this element in the conference document, the server can inform the subscribers about the changes in the overall conference information. The child elements are described below. 5.4.1 This element contains the current number of users in the conference. Rosenberg, et al. Expires September 26, 2005 [Page 14] Internet-Draft Conference Package March 2005 5.4.2 This Boolean element says whether the conference is currently active or not. A conference is active if dialing into one of the results in successful establishment of a call signaling session between the dialed user and the conference focus. 5.4.3 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 of The element is a container of child elements, each describing a single participant in the conference. The following attributes are defined for 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" 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 element: Rosenberg, et al. Expires September 26, 2005 [Page 15] Internet-Draft Conference Package March 2005 5.5.1 This element is used to display the user friendly name in the conference. 5.5.2 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 This element is used to display the roles of the user in the conference. 5.5.4 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 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 By including one or more elements under a parent 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 with its own sub-element(s) in the conference document. Rosenberg, et al. Expires September 26, 2005 [Page 16] Internet-Draft Conference Package March 2005 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 element. Note that in this case, the detailed call signaling information (represented by sub-element) will not be included. 5.6 This section describes the element in more detail. The following attributes are defined for element: entity: The server MUST generate the 'entity' key for each element included under the parent , 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 element: 5.6.1 This element contains the display text for the endpoint. 5.6.2 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. Rosenberg, et al. Expires September 26, 2005 [Page 17] Internet-Draft Conference Package March 2005 5.6.3 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 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. Rosenberg, et al. Expires September 26, 2005 [Page 18] Internet-Draft Conference Package March 2005 Implementations MAY choose not to generate notifications on these to all participants if it will generate too much traffic. 5.6.4 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 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 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. Rosenberg, et al. Expires September 26, 2005 [Page 19] Internet-Draft Conference Package March 2005 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 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: SIP ;cause=415 ;text="Unsupported Media Type" by: This element contains the URI of the entity who caused the endpoint to depart the conference. 5.6.8 This element contains information about a single media stream and is included for each media stream being established between the focus and the . Note that if the 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 were established by separate signaling sessions. 5.6.9 The 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 sub-element contains the SIP dialog identifier of the endpoint's dialog with the focus. The element includes sub-elements , , , . Rosenberg, et al. Expires September 26, 2005 [Page 20] Internet-Draft Conference Package March 2005 In future, the element can be expanded to include call signaling protocol information for other protocols besides SIP. 5.7 This section describes the 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 : 5.7.1 This element contains the display text for the media stream. 5.7.2 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 The 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 The 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)." Rosenberg, et al. Expires September 26, 2005 [Page 21] Internet-Draft Conference Package March 2005 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 The 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. For example, a muted participant's stream will have the value of "recvonly". 5.8 This element contains a set of 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 This element contains a set of 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 Rosenberg, et al. Expires September 26, 2005 [Page 22] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 23] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 24] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 25] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 26] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 27] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 28] Internet-Draft Conference Package March 2005 Rosenberg, et al. Expires September 26, 2005 [Page 29] Internet-Draft Conference Package March 2005 7. Examples 7.1 Basic Example The following is an example conference information document:

Agenda: This month's goals

http://sharepoint/salesgroup/ web-page

Bob Hoskins

Bob's Laptop

disconnected

departed

2005-03-04T20:00:00Z bad voice quality sip:mike@example.com Rosenberg, et al. Expires September 26, 2005 [Page 30] Internet-Draft Conference Package March 2005

main audio

audio 34567

432424

sendrecv

Alice

connected

dialed-out

2005-03-04T20:00:00Z sip:mike@example.com

main audio

audio 34567

534232

sendrecv Rosenberg, et al. Expires September 26, 2005 [Page 31] Internet-Draft Conference Package March 2005 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.

Weekly Sales Meeting

Agenda: This month's goals

We will start strict on time

sales, meeting, weekly

tel:+18005671234

TTI Bridge

participation h323:conf545@h323.example.com participation http://real.streaming.com/54634/live.ram streaming

http://sharepoint/salesgroup/ web-page http://quicktime.com/54634/recording.mov Rosenberg, et al. Expires September 26, 2005 [Page 32] Internet-Draft Conference Package March 2005 Quicktime recording

100

main audio

audio sendrecv

main video

video inactive

Sales Host

http://sharepoint/salesgroup/hosts/

sip:sales@example.com

true false

Bob Hoskins Rosenberg, et al. Expires September 26, 2005 [Page 33] Internet-Draft Conference Package March 2005 mailto:bob@example.com

participant en

Bob's Laptop

2005-03-04T20:00:00Z expert required sip:mike@example.com disconnecting

dialed-out

2005-03-04T20:00:00Z invitation sip:mike@example.com

booted

2005-03-04T20:00:00Z bad voice quality sip:mike@example.com

full info

hsjh8980vhsb78

vav738dvbs

8954jgjg8432

main audio

audio 34567

432424

sendrecv

sips:conf233@example.com; grid=45

sidebar with Carol

sips:conf233@example.com; grid=21

private sidebar with Peter

8. Security Considerations Subscriptions to conference state can reveal very sensitive information. For this reason, the document recommends authentication Rosenberg, et al. Expires September 26, 2005 [Page 35] Internet-Draft Conference Package March 2005 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 Rosenberg, et al. Expires September 26, 2005 [Page 36] Internet-Draft Conference Package March 2005 Interoperability considerations: none Published specification: This document Applications which use this media type: This document type has been used to support SIP conferencing applications Additional Information: Magic Number: None File Extension: .cif or .xml Macintosh file type code: "TEXT" Personal and email address for further information: Jonathan Rosenberg, Intended usage: COMMON Author/Change controller: The IETF 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, , Jonathan Rosenberg XML: BEGIN Conference Information Namespace

Namespace for Conference Information

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

See RFCXXXX.

END Rosenberg, et al. Expires September 26, 2005 [Page 37] Internet-Draft Conference Package March 2005 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 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: Rosenberg, et al. Expires September 26, 2005 [Page 38] Internet-Draft Conference Package March 2005 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 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 Rosenberg, et al. Expires September 26, 2005 [Page 39] Internet-Draft Conference Package March 2005 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 Rosenberg, et al. Expires September 26, 2005 [Page 40] Internet-Draft Conference Package March 2005 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 Rosenberg, et al. Expires September 26, 2005 [Page 41] Internet-Draft Conference Package March 2005 Orit Levin (editor) Microsoft Corporation One Microsoft Way Redmond, WA 98052 US Email: oritl@microsoft.com Rosenberg, et al. Expires September 26, 2005 [Page 42] Internet-Draft Conference Package March 2005 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 made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Rosenberg, et al. Expires September 26, 2005 [Page 43]