XEP-0338: Jingle Grouping Framework

WARNING: This Standards-Track document is Experimental. Publication as an XMPP Extension Protocol does not imply approval of this proposal by the XMPP Standards Foundation. Implementation of the protocol described herein is encouraged in exploratory implementations, but production systems are advised to carefully consider whether it is appropriate to deploy implementations of this protocol before it advances to a status of Draft.

Table of Contents

1. Introduction

RFC 5888 [1] defines a framework to group SDP 'm' lines for different purposes. A mapping to Jingle as an extension to Jingle (XEP-0166) [2] is defined in this document.

It is anticipated that the primary use of this is with the draft-ietf-mmusic-sdp-bundle-negotiation [3] framework used in WebRTC.

2. Mapping to Session Description Protocol

The SDP format defined in RFC 5888 is shown below.

a=group:semantics identification-tag
  

An example follows.

a=group:LS voice webcam
  

This SDP attribute is translated to Jingle as a <group/> element qualified by the 'urn:xmpp:jingle:apps:grouping:0' namespace, as shown below. The semantics is mapped to a 'semantics' attribute. The identification-tags are mapped to content elements whose name attribute is set to the identification-tag.

<group xmlns='urn:xmpp:jingle:apps:grouping:0' semantics='semantics'>
  <content name='identification-tag 1'/>
  <content name='identification-tag 2'/>
</group>

An example follows.

<group xmlns='urn:xmpp:jingle:apps:grouping:0' semantics='LS'>
  <content name='voice'/>
  <content name='webcam'/>
</group>

The <group/> element is included as child of the <jingle/> element.

<iq from='romeo@montague.lit/orchard'
    id='rg6s5134'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <group xmlns='urn:xmpp:jingle:apps:grouping:0' semantics='BUNDLE'>
      <content name='voice'/>
      <content name='webcam'/>
    </group>
    <content creator='initiator' name='voice'>
      [ ... ]
    </content>
    <content creator='initiator' name='webcam'>
      [ ... ]
    </content>
  </jingle>
</iq>

Note: the identification-tags correspond to the <content/> 'name' attributes. These in turn map to the 'mid' attribute in SDP.

3. Determining Support

If an entity supports the grouping framework described in RFC 5888, it MUST advertise that fact in its responses to Service Discovery (XEP-0030) [4] information ("disco#info") requests by returning a feature of 'urn:ietf:rfc:5888':

Example 1. A disco#info query

<iq type='get'
    from='calvin@usrobots.lit/lab'
    to='herbie@usrobots.lit/home'
    id='disco1'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>

Example 2. A disco#info response

<iq type='result'
    from='herbie@usrobots.lit/home'
    to='calvin@usrobots.lit/lab'
    id='disco1'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:jingle:1'/>
    <feature var='urn:ietf:rfc:5888'/>
  </query>
</iq>

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in Entity Capabilities (XEP-0115) [5]. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

4. Acknowledgements

Thanks to Emil Ivov and Lance Stout for their feedback.

The XML format for this specification originates from libjingle [6].

5. Security Considerations

This document introduces no additional security considerations above and beyond those defined in the documents on which it depends.

6. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [7].

7. XMPP Registrar Considerations

8. XML Schema

TODO

Appendices

Appendix A: Document Information

Series: XEP
Number: 0338
Publisher: XMPP Standards Foundation
Status: Experimental
Type: Standards Track
Version: 0.1
Last Updated: 2014-01-08
Approving Body: XMPP Council
Dependencies: XEP-0166
Supersedes: None
Superseded By: None
Short Name: NOT_YET_ASSIGNED
Source Control: HTML
This document in other formats: XML  PDF

Appendix B: Author Information

Appendix C: Legal Notices

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".

Appendix G: Notes

Appendix H: Revision History

Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/

END