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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>Atomically Compare-And-Publish PubSub Items</title>
+  <abstract>This specification provides a mechanism to atomically Compare-And-Publish items to a PubSub node.</abstract>
+  &LEGALNOTICE;
+  <number>xxxx</number>
+  <status>ProtoXEP</status>
+  <type>Standards Track</type>
+  <sig>Standards</sig>
+  <approver>Council</approver>
+  <dependencies>
+    <spec>XEP-0030</spec>
+    <spec>XEP-0060</spec>
+  </dependencies>
+  <supersedes/>
+  <supersededby/>
+  <shortname>cap</shortname>
+  &flow;
+  <revision>
+    <version>0.0.1</version>
+    <date>2017-04-20</date>
+    <initials>fs</initials>
+    <remark><p>First draft.</p></remark>
+  </revision>
+</header>
+
+<section1 topic='Introduction' anchor='intro'>
+
+  <p>This specification provides a mechanism to atomically publish
+  items to a PubSub node depending on the item ID of the node's latest
+  item. This allows to prevent race conditions and avoids data
+  loss in certain situations.</p>
+
+</section1>
+
+<section1 topic='Discoverying Support' anchor='disco'>
+
+  <p>If an entity supports the Compared-And-Publish feature it MUST
+  advertise the fact by returning a &lt;feature/&gt; with the 'var'
+  attribute set to 'urn:xmpp:pubsub:cap:0' in response to a &xep0030;
+  query for information.</p>
+
+</section1>
+
+<section1 topic='Compare-And-Publish PubSub Items' anchor='cap'>
+
+  <p>In order to atomically compare-and-publish an item, a client
+  sends an &IQ; with a 'pubsub' element qualified by the
+  'urn:xmpp:pubsub:cap:0' namespace. The element MUST contain the same
+  attributes and elements as the &lt;publish/&gt; element defined in
+  &xep0060; <em>and</em> it MUST contain a previd attribute containing
+  an item ID.</p>
+
+  <p>The PubSub service MUST only publish the item if the node's
+  latest item ID is equal to the ID found in the 'previd'
+  attribute.</p>
+
+  <example caption='Publisher publishes an item using Compare-And-Publish'><![CDATA[
+<iq type='set'
+    from='hamlet@denmark.lit/blogbot'
+    to='pubsub.shakespeare.lit'
+    id='compare-and-publish1'>
+  <pubsub xmlns='urn:xmpp:pubsub:cap:0'>
+    <compare-and-publish
+        node='princely_musings'
+        previd='1'>
+      <item>
+        <entry xmlns='http://www.w3.org/2005/Atom'>
+          <title>Soliloquy</title>
+          <summary>
+To be, or not to be: that is the question:
+Whether 'tis nobler in the mind to suffer
+The slings and arrows of outrageous fortune,
+Or to take arms against a sea of troubles,
+And by opposing end them?
+          </summary>
+          <link rel='alternate' type='text/html'
+                href='http://denmark.lit/2003/12/13/atom03'/>
+          <id>tag:denmark.lit,2003:entry-32397</id>
+          <published>2003-12-13T18:30:02Z</published>
+          <updated>2003-12-13T18:30:02Z</updated>
+        </entry>
+      </item>
+    </publish>
+  </pubsub>
+</iq>
+]]></example>
+
+  <section2 topic='Successfully published an item using Compare-And-Publish'>
+
+	<p>If the 'previd' matched the latest item's ID and if the service
+	was able to successfully process the request then the protocol
+	continues as defined in <cite>XEP-0060 7.1.2</cite>.</p>
+
+  </section2>
+
+  <section2 topic='Could not publish because newest item ID did not match'>
+
+    <p>In case the Compare-And-Publish operation failed because the
+    latest node id is not the same as given in the 'previd' attribute
+    in the request, the server returns an &IQ; result with 'pubsub'
+    element qualified by the 'urn:xmpp:pubsub:cap:0' namespace which
+    contains a &lt;compare-and-publish-failed/&gt; element. The
+    element MUST have a 'id' attribute with the ID of the lastest
+    item.</p>
+
+   <example caption='Service returns IQ response notifying of failed Compare-And-Publish operation'><![CDATA[
+<iq type='result'
+    from='pubsub.shakespeare.lit'
+    to='hamlet@denmark.lit/blogbot'
+    id='compare-and-ublish1'>
+  <pubsub xmlns='urn:xmpp:pubsub:cap:0'>
+    <compare-and-publish-failed id='2'/>
+  </pubsub>
+</iq>
+]]></example>
+
+  </section2>
+
+  <section2 topic='Error cases'>
+
+    <p>All other error cases are handled as specified in
+    <cite>XEP-0060 § 7.1.3</cite></p>
+
+  </section2>
+
+</section1>
+
+<section1 topic='Security Considerations' anchor='security'>
+
+  <p>This extension protocol does not add any further security
+  considerations to the ones mentioned in <cite>XEP-0060 §
+  14.</cite>.</p>
+
+</section1>
+
+<section1 topic='IANA Considerations' anchor='iana'>
+
+  <p>This document requires no interaction with the Internet Assigned
+  Numbers Authority (IANA).</p>
+
+</section1>
+
+<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
+
+  <p>This specification defines the following XML namespaces:</p>
+  <ul>
+    <li>urn:xmpp:pubsub:cap:0</li>
+  </ul>
+  	<code caption='Registry Submission'><![CDATA[
+<var>
+	<name>urn:xmpp:pubsub:cap:0</name>
+	<desc>Indicates support for Compare-And-Publish</desc>
+	<doc>XEP-XXXX</doc>
+</var>]]></code>
+
+</section1>
+<section1 topic='XML Schema' anchor='schema'>
+
+  <p>TODO: Add after the XEP leaves the 'experimental' state.</p>
+
+</section1>
+</xep>