XCON G. Camarillo Internet-Draft Ericsson Intended status: Standards Track S. Srinivasan Expires: March 8, 2009 Microsoft Corporation R. Even Polycom J. Urpalainen Nokia September 4, 2008 Conference Event Package Data Format Extension for Centralized Conferencing (XCON) draft-ietf-xcon-event-package-01.txt Status of this Memo 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 becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 March 8, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document specifies the notification mechanism for XCON (centralized conferencing). This mechanism reuses the SIP (Session Camarillo, et al. Expires March 8, 2009 [Page 1]
Internet-Draft XCON Event Package September 2008 Initiation Protocol) event package for conference state. Additionally, the notification mechanism includes support for the XCON data model and for partial notifications. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Notification Formats . . . . . . . . . . . . . . . . . . . . . 4 4. Full Notifications . . . . . . . . . . . . . . . . . . . . . . 4 4.1. Backwards Compatibility . . . . . . . . . . . . . . . . . 5 5. Partial Notifications . . . . . . . . . . . . . . . . . . . . 5 5.1. Generation of Partial Notifications . . . . . . . . . . . 5 5.2. Processing of Partial Notifications . . . . . . . . . . . 6 5.3. Partial Notification Format . . . . . . . . . . . . . . . 7 5.4. XML Schema for Partial Notifications . . . . . . . . . . . 7 5.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6.1. MIME type Registration: application/xcon-conference-info+xml . . . . . . . . . . . 9 6.2. MIME type Registration: application/xcon-conference-info-diff+xml . . . . . . . . 10 6.3. URN Sub-Namespace Registration: consent-status . . . . . . 11 6.4. XML Schema Registration . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. Normative References . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . . . 14 Camarillo, et al. Expires March 8, 2009 [Page 2]
Internet-Draft XCON Event Package September 2008 1. Introduction The XCON (centralized Conferencing) framework [I-D.ietf-xcon-framework] defines a notification service that provides updates about a conference instance's state to authorized parties using a notification protocol, as shown in Figure 1. This document specifies how to use the SIP (Session Initiation Protocol [RFC3261]) event package for conference state defined in [RFC4575] as a notification protocol between a client and a conference's notification server. ........................... . Conferencing System . . . . +--------------+ . . | Conf. object | . . | | . . +--------------+ . . | . . v . . +------------+ . . |Notification| . . |Service | . . +------------+ . . ^ . ..........|................ | | Notification | Protocol |(notifications following the | XCON data model) | ..........|............ . v . . +------------+ . . |Notification| . . | Client | . . +------------+ . . . . Conferencing Client . ....................... Figure 1: Notification service and protocol in the XCON architecture In addition to specifying the SIP event package for conference state, [RFC4575] specifies a data format to be used with the event package. The XCON data model [I-D.ietf-xcon-common-data-model] extends that format with new elements and attributes so that the extended format Camarillo, et al. Expires March 8, 2009 [Page 3]
Internet-Draft XCON Event Package September 2008 supports more functionality (e.g., floor control). The notification protocol specified in this document supports all the data defined in the XCON data model (i.e., the data originally defined in [RFC4575] plus all the extensions defined in [I-D.ietf-xcon-common-data-model]) plus a partial notification mechanism based on XML patch operations [I-D.ietf-simple-xml-patch-ops]. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Notification Formats In order to obtain notifications from a conference server's notification service, a client subscribes to the 'conference' event package at the server as specified in [RFC4575]. Per [RFC4575], NOTIFY requests within this event package can carry an XML document in the "application/conference-info+xml" format. Additionally, per this specification, NOTIFY requests can also carry XML documents in the "application/xcon-conference-info+xml" and the "application/ xcon-conference-info-diff+xml" formats. A document in the "application/xcon-conference-info+xml" format provides the user agent with the whole state of a conference instance. A document in the "application/ xcon-conference-info-diff+xml" format provides the user agent with the changes the state of the conference instance has experimented since the last notification sent to the user agent. 4. Full Notifications Subscribers signal support for full notifications by including the "application/xcon-conference-info+xml" format in the Accept header field of the SUBSCRIBE requests they generate. If a client subscribing to the 'conference' event package generates an Accept header field that includes the MIME type "application/ xcon-conference-info+xml", the server has the option of returning documents that follow the XML format specified in [I-D.ietf-xcon-common-data-model] and are carried in "application/ xcon-conference-info+xml" message bodies. Camarillo, et al. Expires March 8, 2009 [Page 4]
Internet-Draft XCON Event Package September 2008 4.1. Backwards Compatibility Conference servers that implement the SIP event package for conference state and support the "application/ xcon-conference-info+xml" MIME type MUST also support the "application/conference-info+xml" MIME type. This way, legacy clients, which only support "application/conference-info+xml", are able to receive notifications in a format they understand. Clients that implement the SIP event package for conference state and support the "application/xcon-conference-info+xml" MIME type SHOULD also support the "application/conference-info+xml" MIME type. This way, these clients are able to receive notifications from legacy servers, which only support "application/conference-info+xml", in a format they understand. 5. Partial Notifications The conference state reported by this event package may contain many elements. When the "xcon-conference-info+xml" format is used and there is a change in the state of an element, the server generates a notification with the whole conference state. Generating large notifications to report small changes does not meet the efficiency requirements of some bandwidth-constrained environments. The partial notifications mechanism specified in this section is a more efficient way to report changes in the conference state. The SIP event package for conference state defined a partial notification mechanism based on <state> elements. Servers compliant with this specification MUST NOT use that partial notification mechanism. Instead, they MUST use the mechanism specified in this section. Subscribers signal support for partial notifications by including the "application/xcon-conference-info-diff+xml" format in the Accept header field of the SUBSCRIBE requests they generate. If a client subscribing to the 'conference' event package generates an Accept header field that includes the MIME type "application/ xcon-conference-info-diff+xml", the server has the option of returning documents that follow the XML format specified in Section 5.4 and are carried in "application/ xcon-conference-diff-info+xml" message bodies. 5.1. Generation of Partial Notifications Once a subscription is accepted and installed, the server MUST deliver full state in its first notification. To report full state, Camarillo, et al. Expires March 8, 2009 [Page 5]
Internet-Draft XCON Event Package September 2008 the server MUST set the Content-Type header field to the value 'application/xcon-conference-info+xml'. In order to deliver a partial notification, the server MUST set the Content-Type header field to the value 'application/ xcon-conference-info-diff+xml'. When the server generates a partial notification, the server SHOULD only include the information that has changed compared to the previous notification. It is up to the server's local policy to determine what is considered as a change to the previous state. The server MUST construct partial notifications according to the following logic: all the information that has been added to the document is listed inside <add> elements. All information that has been removed from the document is listed inside <remove> elements and all information that has been changed is listed under <replace> elements. The server MUST NOT send a new NOTIFY request with a partial notification until it has received a final response from the subscriber for the previous one or the previous NOTIFY request has timed out. When the server receives a SUBSCRIBE request (refresh or termination) within the associated subscription, it SHOULD send a NOTIFY request containing the full document using the 'application/ xcon-conference-info+xml' content type. If the server has used a content type other than 'application/ xcon-conference-info+xml' in notifications within the existing subscription and changes to deliver partial notifications, the server MUST deliver full state using the 'application/ xcon-conference-info+xml' content type before generating its first partial notification. 5.2. Processing of Partial Notifications When a subscriber receives the first notification containing full state in a 'application/xcon-conference-info+xml' MIME body, the subscriber MUST store the received full document as its local copy. When the subscriber receives a subsequent notification, the subscriber MUST modify its locally-stored information according to the following logic: o If the notification carries an 'application/ xcon-conference-info+xml' document, the subscriber MUST replace its local copy of the document with the document received in Camarillo, et al. Expires March 8, 2009 [Page 6]
Internet-Draft XCON Event Package September 2008 notification. o If the notification carries an 'application/ xcon-conference-info-diff+xml' document, the subscriber MUST apply the changes indicated in the received 'application/ xcon-conference-info-diff+xml' document to its local copy of the full document. If subscriber encounters a processing error while processing an 'application/xcon-conference-info-diff+xml' encoded document, the subscriber SHOULD renew its subscription. A subscriber can fall back to normal operations by not including the "application/ xcon-conference-info-diff+xml' format in a new SUBSCRIBE request. If the server changes the content type used in notifications within the existing subscription, the subscriber MUST discard all the previously received information and process the new content as specified for that content type. 5.3. Partial Notification Format A xcon-conference-info-diff diff document is an XML [W3C.REC-xml-20060816] document that MUST be well-formed and SHOULD be valid. The namespace URI for the <conference-info-diff> root document element is defined in [I-D.ietf-xcon-common-data-model] : urn:ietf:params:xml:ns:xcon-conference-info The root document element <conference-info-diff> has a single mandatory attribute, "entity". The value of this attribute is the conference object identifier (XCON-URI) that identifies the conference being described in the document. The content of the <conference-info-diff> element is an unordered sequence of <add>, <replace> and <remove> elements followed by elements from other namespaces for the purposes of extensibility. Any such unknown elements MUST be ignored by the client. The <add>, <replace> and <remove> elements can contain other extension attributes than what are defined in the corresponding base types of [I-D.ietf-simple-xml-patch-ops]. 5.4. XML Schema for Partial Notifications This is the XML schema for the "application/ xcon-conference-info-diff+xml" data format. The "urn:ietf:params:xml:schema:xml-patch-ops" schema is defined in [I-D.ietf-simple-xml-patch-ops]. Camarillo, et al. Expires March 8, 2009 [Page 7]
Internet-Draft XCON Event Package September 2008 <?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="urn:ietf:params:xml:ns:xcon-conference-info" xmlns="urn:ietf:params:xml:ns:xcon-conference-info" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"> <!-- include patch-ops type definitions --> <xs:include schemaLocation="urn:ietf:params:xml:schema:patch-ops"/> <!-- partial updates --> <xs:element name="conference-info-diff"> <xs:complexType> <xs:sequence minOccurs="0" maxOccurs="unbounded"> <xs:choice> <!-- add some content --> <xs:element name="add"> <xs:complexType mixed="true"> <xs:complexContent> <xs:extension base="add"> <xs:anyAttribute processContents="lax"/> </xs:extension> </xs:complexContent> </xs:complexType> </xs:element> <!-- remove some content --> <xs:element name="remove"> <xs:complexType> <xs:complexContent> <xs:extension base="remove"> <xs:anyAttribute processContents="lax"/> </xs:extension> </xs:complexContent> </xs:complexType> </xs:element> <!-- replace some content --> <xs:element name="replace"> <xs:complexType mixed="true"> <xs:complexContent> <xs:extension base="replace"> <xs:anyAttribute processContents="lax"/> </xs:extension> </xs:complexContent> </xs:complexType> </xs:element> <!-- allow extension elements from other namespaces --> <xs:any namespace="##other" processContents="lax"/> Camarillo, et al. Expires March 8, 2009 [Page 8]
Internet-Draft XCON Event Package September 2008 </xs:choice> </xs:sequence> <xs:attribute name="entity" type="xs:anyURI" use="required"/> <xs:anyAttribute processContents="lax"/> </xs:complexType> </xs:element> </xs:schema> 5.5. Examples The following is an 'application/xcon-conference-info-diff+xml' partial update document: <?xml version="1.0" encoding="UTF-8"?> <conference-info-diff xmlns="urn:ietf:params:xml:ns:xcon-conference-info" entity="conference123@example.com"> <add sel="*/users/allowed-users-list"> <target uri="sip:john@example.com" method="refer"/> </add> <replace sel="*/conference-state/user-count/text()">5</replace> </conference-info-diff> 6. IANA Considerations There are four IANA considerations associated with this specification. 6.1. MIME type Registration: application/xcon-conference-info+xml This section registers the 'application/xcon-conference-info+xml' MIME type. MIME media type name: application MIME subtype name: xcon-conference-info+xml Mandatory parameters: none Optional Parameters: Same as charset parameter application/xml as specified in [RFC3023]. Camarillo, et al. Expires March 8, 2009 [Page 9]
Internet-Draft XCON Event Package September 2008 Encoding considerations: Same as encoding considerations of application/xml as specified in [RFC3023]. Security considerations: Security considerations: See Section 10 of [RFC3023]. Interoperability considerations: none Published specification: RFC xxxx (Note to the RFC Editor: Please replace XXXX with the RFC Number of this specification.) Applications that use this media type: This document type has been defined to support centralized conferencing applications. Additional Information: Magic Number: none File extension: .xml Macintosh file type code: "TEXT" Personal and email address for further information: IETF XCON Working Group <xcon@ietf.org> Intended usage: COMMON Author/Change controller: The IETF. 6.2. MIME type Registration: application/xcon-conference-info-diff+xml This section registers the 'application/ xcon-conference-info-diff+xml' MIME type. MIME media type name: application MIME subtype name: xcon-conference-info-diff+xml Mandatory parameters: none Optional Parameters: Same as charset parameter application/xml as specified in [RFC3023]. Encoding considerations: Same as encoding considerations of application/xml as specified in [RFC3023]. Security considerations: Security considerations: See Section 10 of [RFC3023]. Interoperability considerations: none Published specification: RFC xxxx (Note to the RFC Editor: Please replace XXXX with the RFC Number of this specification.) Applications that use this media type: This document type has been defined to support partial notifications in centralized conferencing applications. Additional Information: Magic Number: none Camarillo, et al. Expires March 8, 2009 [Page 10]
Internet-Draft XCON Event Package September 2008 File extension: .xml Macintosh file type code: "TEXT" Personal and email address for further information: IETF XCON Working Group <xcon@ietf.org> Intended usage: COMMON Author/Change controller: The IETF. 6.3. URN Sub-Namespace Registration: consent-status This section registers a new XML namespace per the procedures in [RFC3688]. URI: urn:ietf:params:xml:ns:xcon-conference-info-diff Registrant Contact: IETF SIPPING working group, <sipping@ietf.org>, Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com> XML: <?xml version="1.0"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN" "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="content-type" content="text/html;charset=iso-8859-1"/> <title>Partial Notifications in Centralized Conferencing</title> </head> <body> <h1>Namespace for Partial Notifications in</h1> <h1>Centralized Conferencing</h1> <h2>urn:ietf:params:xml:ns:xcon-conference-info-diff</h2> <p>See <a href="[URL of published RFC]">RFCXXXX [[NOTE TO RFC-EDITOR/IANA: Please replace XXXX with the RFC Number of this specification]]</a>.</p> </body> </html> 6.4. XML Schema Registration This section registers an XML schema per the procedures in [RFC3688]. URI: urn:ietf:params:xml:schema:xcon-conference-info-diff Registrant Contact: IETF XCON working group, <xcon@ietf.org>, Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com> Camarillo, et al. Expires March 8, 2009 [Page 11]
Internet-Draft XCON Event Package September 2008 The XML for this schema can be found in Section 5.4. 7. Security Considerations This document specifies how to deliver notifications using the SIP event package for conference state in two new formats. The fact that notifications are encoded in a different format does not have security implications. Section 8 of [RFC4575] contains security considerations related to the use of the event package. Implementers of the event package need to follow those considerations regardless of the format used to encode their notifications. 8. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [RFC3261] 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. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session Initiation Protocol (SIP) Event Package for Conference State", RFC 4575, August 2006. [W3C.REC-xml-20060816] Paoli, J., Yergeau, F., Bray, T., Sperberg-McQueen, C., and E. Maler, "Extensible Markup Language (XML) 1.0 (Fourth Edition)", World Wide Web Consortium Recommendation REC-xml-20060816, August 2006, <http://www.w3.org/TR/2006/REC-xml-20060816>. [I-D.ietf-simple-xml-patch-ops] Urpalainen, J., "An Extensible Markup Language (XML) Patch Operations Framework Utilizing XML Path Language (XPath) Selectors", draft-ietf-simple-xml-patch-ops-04 (work in progress), November 2007. [I-D.ietf-xcon-framework] Camarillo, et al. Expires March 8, 2009 [Page 12]
Internet-Draft XCON Event Package September 2008 Barnes, M., Boulton, C., and O. Levin, "A Framework for Centralized Conferencing", draft-ietf-xcon-framework-10 (work in progress), November 2007. [I-D.ietf-xcon-common-data-model] Novo, O., Camarillo, G., Morgan, D., and R. Even, "Conference Information Data Model for Centralized Conferencing (XCON)", draft-ietf-xcon-common-data-model-08 (work in progress), December 2007. Authors' Addresses Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420 Finland Email: Gonzalo.Camarillo@ericsson.com Srivatsa Srinivasan Microsoft Corporation One Microsoft Way Redmond, WA 98052 USA Email: srivats@microsoft.com Roni Even Polycom 94 Derech Em Hamoshavot Petach Tikva 49130 Israel Email: roni.even@polycom.co.il Jari Urpalainen Nokia Itamerenkatu 11-13 Helsinki 00180 Finland Email: jari.urpalainen@nokia.com Camarillo, et al. Expires March 8, 2009 [Page 13]
Internet-Draft XCON Event Package September 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property 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. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Camarillo, et al. Expires March 8, 2009 [Page 14]