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<?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 &lt;subscribe/&gt; 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 &lt;subscribe/&gt; element as a child of the &lt;query/&gt; 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 &lt;subscribe/&gt; element as a child of the &lt;query/&gt; element and the requesting entity is allowed to receive notifications, the responding entity MUST return the service discovery items (including a &lt;subscription/&gt; 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 &REGISTRAR;.</p>
</section1>
</xep>