xeps/xep-0452.xml

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<!DOCTYPE xep SYSTEM 'xep.dtd' [
  <!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
  <title>MUC Mention Notifications</title>
  <abstract>This specification documents how a user may be informed when they're mentioned in a MUC which they're not currently joined to.</abstract>
  &LEGALNOTICE;
  <number>0452</number>
  <status>Experimental</status>
  <type>Standards Track</type>
  <sig>Standards</sig>
  <approver>Council</approver>
  <dependencies>
    <spec>XMPP Core</spec>
    <spec>XEP-0001</spec>
    <spec>Etc.</spec>
  </dependencies>
  <supersedes/>
  <supersededby/>
  <shortname>NOT_YET_ASSIGNED</shortname>
  &jcbrand;
  <author>
    <firstname>Severino</firstname>
    <surname>Ferrer de la Peñita</surname>
    <email>soul@blastersklan.com</email>
    <jid>soul@blastersklan.com</jid>
  </author>
  &mwild;
  <revision>
    <version>0.1.0</version>
    <date>2021-01-26</date>
    <initials>XEP Editor (jsc)</initials>
    <remark>Accepted by vote of Council on 2021-01-06.</remark>
  </revision>
  <revision>
    <version>0.0.1</version>
    <date>2020-12-17</date>
    <initials>jcb</initials>
    <remark><p>First draft.</p></remark>
  </revision>
</header>

<section1 topic='Introduction' anchor='intro'>
    <p>The &xep0045; specification does not provide for a mechanism whereby an user might be informed of being mentioned in a Multi-User Chat (MUC) without being present as an occupant of that MUC.</p>
    <p>This XEP aims to provide a standardized way in which this might be achieved.</p>
    <p>Concerning "being mentioned" in a MUC, we will rely on &xep0372; as the means whereby someone is explicitly mentioned in a MUC message.</p>
</section1>

<section1 topic='Requirements' anchor='reqs'>
  <p>A user's client must be able to receive forwarded groupchat messages from a MUC in which the user is mentioned, while not having an active session in that MUC (i.e. without joining it).</p>
  <p>The user will have to be affiliated with the MUC, in order to receive the forwarded groupchat messages and whether or not mesages are forwarded will be determined by a configuration setting on the MUC.</p>
  <p>The MUC owner(s) will therefore determine whether notifications are sent out, and may opt in or out by being affiliated or not with the MUC. Affiliations are long lived associations between users and MUCs, and therefore transcend individual sessions in MUCs.</p>
</section1>

<section1 topic='Use Cases' anchor='usecases'>

  <section2 topic='A MUC is configured to send out mention notifications'>
    <p>When an owner creates or configures a MUC, the service offers the option to send out mention notifications to non-present, but still affiliated users:</p>
    <example caption='Service Sends Configuration Form'><![CDATA[
<iq from='coven@chat.shakespeare.lit'
    id='create1'
    to='crone1@shakespeare.lit/desktop'
    type='result'>
  <query xmlns='http://jabber.org/protocol/muc#owner'>
    <x xmlns='jabber:x:data' type='form'>
      <field type='hidden' var='FORM_TYPE'>
        <value>http://jabber.org/protocol/muc#roomconfig</value>
      </field>
      ...
      <field
          label='Forward messages with mentions to non-present, affiiated users'
          type='boolean'
          var='muc#roomconfig_forwardmentions'>
        <value>0</value>
      </field>
      ...
    </x>
  </query>
</iq>
]]></example>
    <p>The owner specifies a value of "1" or "true" &BOOLEANNOTE; if the feature is desired:</p>
    <example caption='MUC Owner Submits Configuration Form'><![CDATA[
<iq from='coven@chat.shakespeare.lit'
    id='configure1'
    to='crone1@shakespeare.lit/desktop'
    type='set'>
  <query xmlns='http://jabber.org/protocol/muc#owner'>
    <x xmlns='jabber:x:data' type='submit'>
      <field type='hidden' var='FORM_TYPE'>
        <value>http://jabber.org/protocol/muc#roomconfig</value>
      </field>
      ...
      <field var='muc#roomconfig_forwardmentions'>
        <value>true</value>
      </field>
      ...
    </x>
  </query>
</iq>
]]></example>
    <p></p>
  </section2>

  <section2 topic='Notifying a non-present user of being mentioned in a MUC'>
    <p>When an affiliated user in a given MUC is referenced in a 'groupchat' message via &xep0372;, and the MUC is configured to forward mentions, then the MUC will forward the message stanza to the user.</p>
    <example caption='MUC forwards the message to the users client'><![CDATA[
<message to='hag66@shakespeare.lit' from='coven@chat.shakespeare.lit'>
  <mentions xmlns='urn:xmpp:mmn:0'>
    <forwarded xmlns='urn:xmpp:forward:0'>
      <delay xmlns='urn:xmpp:delay' stamp='2020-12-03T14:45:56Z'/>
      <message type='groupchat' id='ad22c55c-5a20-4185-8735-af2eb8d459a9'
          to='coven@chat.shakespeare.lit'
          from='coven@chat.shakespeare.lit/firstwitch'
          xml:lang='en'>
        <body>secondwitch: Thrice the brinded cat hath mew'd.</body>
        <reference xmlns='urn:xmpp:reference:0'
            type='mention'
            begin='0'
            uri='xmpp:hag66@shakespeare.lit'
            end='11'/>
        <stanza-id xmlns='urn:xmpp:sid:0'
                   id='5f3dbc5e-e1d3-4077-a492-693f3769c7ad'
                   by='coven@chat.shakespeare.lit'/>
      </message>
    </forwarded>
  </mentions>
</message>
]]></example>
    <p>Notice that in the example above, the entire original 'groupchat' message (including elements added server-side, like the &xep0359; stanza-id) is encapsulated inside a &xep0279; element.</p>
  </section2>
</section1>

<section1 topic='Security Considerations' anchor='security'>
  <p>Similarly to &xep0280;, the security model assumed by this document is that all of the resources for a single user are in the same trust boundary.</p>
  <p>Forwarded groupchat messages leak information of who is currently present in a MUC without requiring the user to join the MUC first to find out.</p>
  <ul>
    <li>Any forwarded copies received by a client MUST be from a valid MUC JID which matches the MUC JID of the encapsulated, forwarded mesages;</li>
    <li>any copies that do not meet this requirement MUST be ignored.</li>
  </ul>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
  <p>None.</p>
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
  <section2 topic='Protocol Namespaces' anchor='ns'>
    <p>The &REGISTRAR; includes 'urn:xmpp:mmn:0' in its registry of protocol namespaces (see &NAMESPACES;).</p>
    <ul>
      <li>urn:xmpp:mmn:0</li>
    </ul>
  </section2>
  <section2 topic='Protocol Versioning' anchor='registrar-versioning'>
    &NSVER;
  </section2>
</section1>
</xep>