<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE xep SYSTEM 'xep.dtd' [ <!ENTITY % ents SYSTEM 'xep.ent'> %ents; ]> <?xml-stylesheet type='text/xsl' href='xep.xsl'?> <xep> <header> <title>Service Discovery Notifications</title> <abstract>This specification defines a method for requesting and receiving notifications regarding XMPP service discovery items.</abstract> &LEGALNOTICE; <number>0230</number> <status>Deferred</status> <type>Standards Track</type> <sig>Standards</sig> <approver>Council</approver> <dependencies> <spec>XMPP Core</spec> <spec>XEP-0030</spec> <spec>XEP-0060</spec> </dependencies> <supersedes/> <supersededby/> <shortname>NOT YET ASSIGNED</shortname> &hildjj; &stpeter; <revision> <version>0.1.1</version> <date>2016-10-04</date> <initials>egp</initials> <remark><p>Add forgotten namespace in example 3, and change the text to describe the correct element.</p></remark> </revision> <revision> <version>0.1</version> <date>2008-01-30</date> <initials>psa</initials> <remark><p>Initial published version.</p></remark> </revision> <revision> <version>0.0.2</version> <date>2008-01-06</date> <initials>jjh/psa</initials> <remark><p>Corrected example to use full JIDs and SubIDs.</p></remark> </revision> <revision> <version>0.0.1</version> <date>2008-01-03</date> <initials>jjh/psa</initials> <remark><p>First draft.</p></remark> </revision> </header> <section1 topic='Introduction' anchor='intro'> <p>&xep0115; defines a way for entities to receive dynamically-updated information about &xep0030; capabilities, rather than polling for updates by sending repeated disco#info requests. However, there is no comparable method for receiving updated disco#items information (this might be helpful when the number of associated entities is large or dynamic, e.g., at a multi-user chat service). This document specifies such a method by re-using semantics from &xep0060;.</p> </section1> <section1 topic='Protocol' anchor='protocol'> <p>Before a requesting entity asks for service discovery items with notifications, it SHOULD send directed presence to the responding entity so that the responding entity knows when to stop sending notifications.</p> <example caption='Requesting entity sends presence'><![CDATA[ <presence from='bill@shakespeare.lit/globe' to='chat.shakespeare.lit'/> ]]></example> <p>The requesting entity then sends a disco#items request to the responding entity, including a <subscribe/> element qualified by the 'http://jabber.org/protocol/pubsub' namespace, which in turn specifies a node of 'http://jabber.org/protocol/disco#items'.</p> <example caption='Requesting all items'><![CDATA[ <iq type='get' from='bill@shakespeare.lit/globe' to='chat.shakespeare.lit' id='items1'> <query xmlns='http://jabber.org/protocol/disco#items'> <subscribe xmlns='http://jabber.org/protocol/pubsub'/> </query> </iq> ]]></example> <p>If the responding entity does not recognize inclusion of the <subscribe/> element as a child of the <query/> element, it MUST return the service discovery items but MUST NOT send subsequent notifications to the requesting entity.</p> <p>If the requesting entity did not share presence with the responding entity, the responding entity MUST return the service discovery items but SHOULD NOT send subsequent notifications to the requesting entity.</p> <p>If the responding entity recognizes inclusion of the <subscribe/> element as a child of the <query/> element and the requesting entity is allowed to receive notifications, the responding entity MUST return the service discovery items (including a <subscription/> element) and SHOULD send subsequent notifications to the requesting entity.</p> <example caption='Result-set for all items'><![CDATA[ <iq type='result' from='chat.shakespeare.lit' to='bill@shakespeare.lit/globe' id='items1'> <query xmlns='http://jabber.org/protocol/disco#items'> <item jid='alls-well-that-ends-well@chat.shakespeare.lit'/> <item jid='as-you-like-it@chat.shakespeare.lit'/> <item jid='cleopatra@chat.shakespeare.lit'/> <item jid='comedy-of-errors@chat.shakespeare.lit'/> <item jid='coriolanus@chat.shakespeare.lit'/> <item jid='cymbeline@chat.shakespeare.lit'/> <item jid='hamlet@chat.shakespeare.lit'/> <item jid='henry-the-fourth-one@chat.shakespeare.lit'/> <item jid='henry-the-fourth-two@chat.shakespeare.lit'/> <item jid='henry-the-fifth@chat.shakespeare.lit'/> <subscription xmlns='http://jabber.org/protocol/pubsub' jid='bill@shakespeare.lit' subid='some-long-sub-id' subscription='subscribed'/> </query> </iq> ]]></example> <p>The responding entity then SHOULD send subsequent notifications to the requesting entity when associated items are added to or deleted from the potential result set.</p> <example caption='A notification (new item)'><![CDATA[ <message from='chat.shakespeare.lit' to='bill@shakespeare.lit' id='foo'> <event xmlns='http://jabber.org/protocol/pubsub#event'> <items node='http://jabber.org/protocol/disco#items'> <item id='ae890ac52d0df67ed7cfdf51b644e901'> <item xmlns='http://jabber.org/protocol/disco#items' jid='henry-the-fifth@chat.shakespeare.lit'/> </item> </items> </event> </message> ]]></example> <example caption='A notification (deleted item)'><![CDATA[ <message from='chat.shakespeare.lit' to='bill@shakespeare.lit' id='bar'> <event xmlns='http://jabber.org/protocol/pubsub#event'> <items node='http://jabber.org/protocol/disco#items'/> <retract id='fa890ca52d0df67de7fcfd51b644c701'> <item xmlns='http://jabber.org/protocol/disco#items' jid='cardenio@chat.shakespeare.lit'/> </retract> </items> </event> </message> ]]></example> <p>When the requesting entity goes offline, the responding entity will receive unavailable presence.</p> <example caption='Responding entity receives unavailable presence'><![CDATA[ <presence from='bill@shakespeare.lit/globe' to='chat.shakespeare.lit' type='unavailable'/> ]]></example> <p>The responding entity then MUST NOT send further notifications.</p> </section1> <section1 topic='Security Considerations' anchor='security'> <p>This document introduces no new security considerations above and beyond those already defined for service discovery and publish-subscribe.</p> </section1> <section1 topic='IANA Considerations' anchor='iana'> <p>This document requires no interaction with &IANA;.</p> </section1> <section1 topic='XMPP Registrar Considerations' anchor='registrar'> <p>This document requires no interaction with the ®ISTRAR;.</p> </section1> </xep>