<?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>Last User Interaction in Presence</title>
  <abstract>This specification defines a way to communicate time of last user interaction with her system using XMPP presence notifications.</abstract>
  &LEGALNOTICE;
  <number>0319</number>
  <status>Draft</status>
  <type>Standards Track</type>
  <sig>Standards</sig>
  <dependencies>
    <spec>XMPP Core</spec>
    <spec>XMPP IM</spec>
    <spec>XEP-0082</spec>
  </dependencies>
  <supersedes>
    <spec>XEP-0256</spec>
  </supersedes>
  <supersededby/>
  <shortname>idle</shortname>
  &tobias;
  <revision>
    <version>1.0</version>
    <date>2015-04-02</date>
    <initials>XEP editor (mam)</initials>
    <remark><p>Per a vote of the XMPP Council, advanced specification from Experimental to Draft.</p></remark>
  </revision>
  <revision>
    <version>0.2</version>
    <date>2013-08-27</date>
    <initials>tobias</initials>
    <remark><p>Fix issues raised in XMPP Council meeting.</p></remark>
  </revision>
  <revision>
    <version>0.1</version>
    <date>2013-03-04</date>
    <initials>psa</initials>
    <remark><p>Initial published version approved by the XMPP Council.</p></remark>
  </revision>
  <revision>
    <version>0.0.1</version>
    <date>2013-02-17</date>
    <initials>tobias</initials>
    <remark><p>Initial version.</p></remark>
  </revision>
</header>
<section1 topic='Introduction' anchor='intro'>
  <p>This protocol describes a way to communicate a user's last interaction time with other XMPP entities over &PRESENCE; stanzas. For the purposes of this document, user interaction here refers to a human end user interacting with her device by means of a keyboard, mouse, touch screen, and so on. Based on this information XMPP clients can display the time a contact went idle or a duration for how long a contact has been idle, thereby allowing end users to estimate the expected responsiveness of their contacts.</p>
  <p>This protocol uses absolute timestamps formatted according to &xep0082;, indicated as value of the 'since' attribute in the &lt;idle/&gt; element.</p>
  <p>Experience has shown a number of issues with &xep0256;:</p>
  <ul>
    <li>The use of relative durations is too vague. It requires additional information from &xep0203; to provide a reliable user experience.</li>
    <li>Distinguishing between the idle and last online use cases is very difficult.</li>
    <li>It is desirable to have idle time indiciated for &PRESENCE; &lt;show/&gt; values other than "away" and "xa".</li>
  </ul>
  <p>Updating <cite>XEP-0256</cite> directly would be problematic as it would break compatibility with existing implementations.  Instead a new protocol is described for handling the idle time use case; the last online use case is handled by &xep0312;.</p>
</section1>
<section1 topic='Use Cases' anchor='usecases'>
  <p>There are two main use cases for this extension, explained in more detail in the following sections.</p>
  <section2 topic='Presence with Last Interaction' anchor='last-interact'>
  <p>After a user has not interacted with her device for some amount of time the user wants to inform her contacts about this fact. The client sends a &PRESENCE; stanza with time of last interaction.</p>
  <example caption='Time of Last User Interaction in Auto-Away'><![CDATA[
<presence from='juliet@capulet.com/balcony'>
  <show>away</show>
  <idle xmlns='urn:xmpp:idle:1' since='1969-07-21T02:56:15Z'/>
</presence>
    ]]></example>
  <p>The amount of time the user has to be idle before a client sends this enhanced presence is application-specific; it is suggested that a sensible default interval of 5 minutes be used.</p>
  </section2>
  <section2 topic='Presence Indicating User Coming Back From Idle' anchor='back-from-idle'>
    When a user comes back and uses her device again the client informs user's contacts by sending a normal presence stanza like shown in the following example, omiting the &lt;idle/&gt; element.
    <example caption='Presence Indicating Return to Device'><![CDATA[
<presence from='juliet@capulet.com/balcony' />
    ]]></example>
  </section2>
</section1>
<section1 topic='XML Schema' anchor='schema'>
    <code><![CDATA[
<?xml version="1.0" encoding="utf-8"?>

<xs:schema
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    targetNamespace="urn:xmpp:idle:1"
    xmlns="urn:xmpp:idle:1">

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0319: http://www.xmpp.org/extensions/xep-0319.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name="idle">
    <xs:complexType>
      <xs:attribute name="since" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

</xs:schema>
      ]]></code>
</section1>
<section1 topic='Acknowledgements' anchor='ack'>
  <p>Thanks to Florian Schmaus, Christian Schudt, and Lance Stout for their helpful comments.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
  <p>The security considerations of <cite>XEP-0082</cite> apply to this protocol.</p>
  <p>This specification introduces no new security or privacy concerns. While including a last user interaction notation in &PRESENCE; updates can enable recipients to determine exactly when a user has stopped interacting with her XMPP client or even their system, this information is in essence already available if the user's client publishes timely presence updates.</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'>
  <section2 topic='Protocol Namespace'>
    <p>The &REGISTRAR; shall add 'urn:xmpp:idle:1' to its registry at <link url='http://xmpp.org/registrar/namespaces.html'>http://xmpp.org/registrar/namespaces.html</link>.</p>
  </section2>
</section1>
</xep>
