XEP-0338: Jingle Grouping Framework

This specification provides an XML mapping for translating the RFC 5888 SDP Grouping Framework to Jingle
Philipp Hancke
© 2013 – 2020 XMPP Standards Foundation. SEE LEGAL NOTICES.


NOTICE: The protocol defined herein is a Stable Standard of the XMPP Standards Foundation. Implementations are encouraged and the protocol is appropriate for deployment in production systems, but some changes to the protocol are possible before it becomes a Final Standard.
Standards Track
1.0.0 (2020-07-21)
Document Lifecycle
  1. Experimental
  2. Proposed
  3. Stable
  4. Final

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'/>

An example follows.

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

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

<iq from='romeo@montague.lit/orchard'
  <jingle xmlns='urn:xmpp:jingle:1'
    <group xmlns='urn:xmpp:jingle:apps:grouping:0' semantics='BUNDLE'>
      <content name='voice'/>
      <content name='webcam'/>
    <content creator='initiator' name='voice'>
      [ ... ]
    <content creator='initiator' name='webcam'>
      [ ... ]

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'
  <query xmlns='http://jabber.org/protocol/disco#info'/>
Example 2. A disco#info response
<iq type='result'
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:jingle:1'/>
    <feature var='urn:ietf:rfc:5888'/>

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

7.1 Protocol Namespaces

This specification defines the following XML namespace:

The XMPP Registrar [8] includes the foregoing namespace to the registry located at <https://xmpp.org/registrar/namespaces.html>, as described in Section 4 of XMPP Registrar Function (XEP-0053) [9].

7.2 Protocol Versioning

If the protocol defined in this specification undergoes a revision that is not fully backwards-compatible with an older version, the XMPP Registrar shall increment the protocol version number found at the end of the XML namespaces defined herein, as described in Section 4 of XEP-0053.

8. XML Schema



Appendix A: Document Information

XMPP Standards Foundation
Standards Track
Last Updated
Approving Body
XMPP Council
Superseded By
Short Name
Source Control

This document in other formats: XML  PDF

Appendix B: Author Information

Philipp Hancke


This XMPP Extension Protocol is copyright © 1999 – 2024 by the XMPP Standards Foundation (XSF).


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Disclaimer of Warranty

## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ##

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In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.

IPR Conformance

This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <https://xmpp.org/about/xsf/ipr-policy> or obtained by writing to XMPP Standards Foundation, P.O. Box 787, Parker, CO 80134 USA).

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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 <https://xmpp.org/community/> 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

1. RFC 5888: The Session Description Protocol (SDP) Grouping Framework <http://tools.ietf.org/html/rfc5888>.

2. XEP-0166: Jingle <https://xmpp.org/extensions/xep-0166.html>.

3. Negotiating Media Multiplexing Using the Session Description Protocol (SDP) <https://datatracker.ietf.org/doc/draft-ietf-mmusic-sdp-bundle-negotiation/>. Work in progress.

4. XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>.

5. XEP-0115: Entity Capabilities <https://xmpp.org/extensions/xep-0115.html>.

6. libjingle is now part of the WebRTC Native Code Package available from webrtc.org.

7. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>.

8. The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the XMPP Standards Foundation. For further information, see <https://xmpp.org/registrar/>.

9. XEP-0053: XMPP Registrar Function <https://xmpp.org/extensions/xep-0053.html>.

Appendix H: Revision History

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

  1. Version 1.0.0 (2020-07-21)
    Advance to Draft as per Council vote from 2020-07-01
    XEP Editor (jsc)
  2. Version 0.2 (2017-09-11)
    Defer due to lack of activity.
    XEP Editor (jwi)
  3. Version 0.1 (2014-01-08)

    Initial published version approved by the XMPP Council.

  4. Version 0.0.1 (2013-11-25)

    First draft.


Appendix I: Bib(La)TeX Entry

  title = {Jingle Grouping Framework},
  author = {Hancke, Philipp},
  type = {XEP},
  number = {0338},
  version = {1.0.0},
  institution = {XMPP Standards Foundation},
  url = {https://xmpp.org/extensions/xep-0338.html},
  date = {2013-11-25/2020-07-21},