XEP-0408: Mediated Information eXchange (MIX): Co-existence with MUC

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

The Mediated Information eXchange (MIX) protocol framework and core capabilities are specified in Mediated Information eXchange (MIX) (XEP-0369) [1] (MIX-CORE). MIX can be used independently of Multi-User Chat (XEP-0045) [2] (MUC).

It may be desirable to operate a service that provides MIX and MUC together. This specification specifies three options for achieving this.

2. Supporting MIX and MUC together

If both MIX and MUC are implemented, three approaches are noted.

1. Entirely separate MIX and MUC implementation, with MIX and MUC using separate domains and MIX channels being completely separate from MUC rooms.
2. Fully integrated MIX and MUC implementation, with MIX and MUC sharing a single domain and rooms/channels equivalent.
3. Partially integrated MIX and MUC implementation, with MIX and MUC using separate domains, but all rooms/channel are common. This means that each MIX channel will have MUC room of the same name and same participants.

The fully integrated approach would be transparent to clients. The following example shows how a service that supports MIX and MUC in a fully integrated manner would respond following the specification of Mediated Information eXchange (MIX) (XEP-0369) [1]:

Example 1. Client uses Disco to show fully integrated MIX and MUC support

<iq from='hag66@shakespeare.example/UUID-c8y/1573'
    id='lx09df27'
    to='mix.shakespeare.example'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
</iq>

<iq from='mix.shakespeare.example'
    id='lx09df27'
    to='hag66@shakespeare.example/UUID-c8y/1573'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <identity
        category='conference'
        name='Shakespearean Chat Service'
        type='text'/>
    <feature var='urn:xmpp:mix:core:0'/>
    <feature var='http://jabber.org/protocol/muc'/>
     <feature var='urn:xmpp:mix:core:0#searchable'>
  </query>
</iq>

In the fully integrated service item discovery on the MIX/MUC service determines a list of channels. The protocol used for this is the same in MUC and MIX. Discovery actions on a channel in MIX MUST use 'node=mix' attribute in the discovery which will lead to the return of MIX channel specific information, as mandated for this discovery in Mediated Information eXchange (MIX) (XEP-0369) [1]. If is not set, MUC room specific information is returned.

For the partially integrated service, MIX servers will reference the associated MUC server and MUC servers will reference the associated MIX service. This will allow a client that only support MUC or only supports MIX to find the right server if it is given a reference to the other one. For a client that supports both MUC and MIX, it will enable the client to select its preferred service. For a MIX client, it will also be useful to know the MUC service, so that this information can be shared with a MUC client invitation. The following example shows how a MIX server identifies the associated MUC server. Note that MUC MUST NOT be advertized as a feature:

Example 2. Client uses Disco to find MUC server assocated with MIX server

<iq from='hag66@shakespeare.example/UUID-c8y/1573'
    id='lx09df27'
    to='mix.shakespeare.example'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
</iq>

<iq from='mix.shakespeare.example'
    id='lx09df27'
    to='hag66@shakespeare.example/UUID-c8y/1573'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <identity
        category='conference'
        name='Shakespearean Chat Service'
        type='text'/>
    <feature var='urn:xmpp:mix:core:0'/>
    <x xmlns='jabber:x:data' type='result'>
      <field var='FORM_TYPE' type='hidden'>
        <value>urn:xmpp:mix:muc:0#muc-mirror</value>
      </field>
      <field var='muc-mirror'
             type='jid-single'
             label='Location of MUC mirror service'>
        <value>chat.shakespeare.example</value>
      </field>
    </x>
  </query>
</iq>

The result is returned in an extended disco results in a form whose type value is 'urn:xmpp:mix:muc:0#muc-mirror'. The field with var='muc-mirror' is the value of which is the mirrored MUC domain's JID.

Similarly, a MUC service can advertise an associated MIX doming. The following example shows discovery of a MUC domain. Note that MIX MUST NOT be advertized as a feature

Example 3. Client uses Disco to find MIX server assocated with MUC server

<iq from='hag66@shakespeare.example/UUID-c8y/1573'
    id='lx09df27'
    to='mix.shakespeare.example'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
</iq>

<iq from='chat.shakespeare.example'
    id='lx09df27'
    to='hag66@shakespeare.example/UUID-c8y/1573'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <identity
        category='conference'
        name='Shakespearean Chat Service'
        type='text'/>
    <feature var='http://jabber.org/protocol/muc'/>
    <x xmlns='jabber:x:data' type='result'>
      <field var='FORM_TYPE' type='hidden'>
        <value>urn:xmpp:mix:muc:0#mix-mirror</value>
      </field>
      <field var='mix-mirror'
             type='jid-single'
             label='Location of MUC mirror service'>
        <value>mix.shakespeare.example</value>
      </field>
    </x>
  </query>
</iq>

The result is returned in an extended disco results in a form whose type value is 'urn:xmpp:mix:muc:0#mux-mirror'. The field with var='mix-mirror' is the value of which is the mirrored MIX domain's JID.

3. Internationalization Considerations

See considerations in Mediated Information eXchange (MIX) (XEP-0369) [1].

4. Security Considerations

See considerations in Mediated Information eXchange (MIX) (XEP-0369) [1].

When converting a 1:1 conversation to a channel there is potential to expose sensitive information and to present invalid information.

5. IANA Considerations

None.

6. XMPP Registrar Considerations

The urn:xmpp:mix namespace needs to be registered.

7. XML Schema

To be supplied when MIX progresses to proposed standard.

8. Acknowledgements

See Mediated Information eXchange (MIX) (XEP-0369) [1] for a list of contributors to the MIX Family of specifications.

Appendices

Appendix A: Document Information

Series: XEP
Number: 0408
Publisher: XMPP Standards Foundation
Status: Experimental
Type: Standards Track
Version: 0.1.0
Last Updated: 2018-05-21
Approving Body: XMPP Council
Dependencies: XMPP Core, XMPP IM, XEP-0004, XEP-0030, XEP-0054, XEP-0060, XEP-0084, XEP-0128, XEP-0198, XEP-0292, XEP-0297, XEP-0313, XEP-0372
Supersedes: None
Superseded By: None
Short Name: MIX-MUC
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/

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