xep-0435.xml

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<xep>
  <header>
	<title>Reminders</title>
	<abstract>This specification provides a way to set up reminders.</abstract>
&LEGALNOTICE;
	<number>0435</number>
	<status>Deferred</status>
	<type>Standards Track</type>
	<sig>Standards</sig>
	<approver>Council</approver>
	<dependencies>
      <spec>XMPP Core</spec>
	  <spec>XEP-0082</spec>
	</dependencies>
	<supersedes/>
	<supersededby/>
	<shortname>NOT_YET_ASSIGNED</shortname>
	<author>
      <firstname>Marcos</firstname>
      <surname>De Vera Piquero</surname>
      <email>marcos@tenak.net</email>
      <jid>marcos@tenak.net</jid>
	</author>
  <revision>
    <version>0.1.0</version>
    <date>2020-03-31</date>
    <initials>XEP Editor (jsc)</initials>
    <remark>Accepted by vote of Council on 2020-03-04.</remark>
  </revision>
	<revision>
      <version>0.0.1</version>
      <date>2020-02-17</date>
      <initials>mdvp</initials>
      <remark><p>Initial version</p></remark>
	</revision>
  </header>
  <section1 topic='Introduction' anchor='intro'>
	<p>It is sometimes useful, while reading some conversations, to be
	reminded about it at some point in the future.  This specification
	proposes a mechanism to allow clients to set up such reminders.</p>
  </section1>
  <!-- <section1 topic='Requirements' anchor='reqs'> -->
  <!--   <p>STRONGLY RECOMMENDED.</p> -->
  <!-- </section1> -->
  <section1 topic='Glossary' anchor='glossary'>
	<dl>
	  <di>
		<dt>Reminder</dt>
		<dd>
		  An automatically generated message addressed to an entity sent
		  at a given time. Its goal is to remind the creating entity
		  about something.
		</dd>
	  </di>
	</dl>
  </section1>
  <section1 topic='Requirements' anchor='requirements'>
	<p>This protocol requires handling of dates and times, as such it conforms to &xep0082;.</p>
  </section1>
  <section1 topic='Discovering support' anchor='disco'>
	<p>An entity may wish to discover if a service supports the Reminders feature; in order to do so, it sends a service discovery information query to the server..</p>
	<example caption='Client requests information about a server'><![CDATA[
<iq from='juliet@capulet.net/balcony'
    id='disco1'
    to='capulet.net'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>]]></example>
	<p>If the server supports the Reminders feature, it MUST specify the
	'urn:xmpp:reminders:0' feature in its service discovery information
	features as specified in &xep0030;</p>
	<example caption='Server advertises support for reminders'><![CDATA[
<iq to='juliet@capulet.net/balcony' id='disco1' from='capulet.net'
	type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    …  
    <feature var='urn:xmpp:reminders:0'/>
    …
  </query>
</iq>]]></example>
  </section1>
  <section1 topic='Use Cases' anchor='usecases'>
	<p>For end users, this provides a way to be reminded about stuff
	while being in a conversation, without the need to leave it and go
	to some calendar application or similar and create a full event
	there. By setting a reminder, a user will be notified by the server
	at whatever given time the reminder is created with and with
	whatever the description was set for such a reminder.</p>
	<section2 topic='Creating a reminder' anchor='creating'>
	  <p>A user wants to create a new reminder. For creating a
	  reminder, an entity MUST send an IQ stanza with the 'type'
	  attribute with a value of "set" and a direct &lt;reminder/&gt;
	  child qualified by the "urn:xmpp:reminders:0" namespace.</p>
	  <example caption='User creates a new reminder'><![CDATA[
<iq from='juliet@capulet.net/balcony'
    to='capulet.net'
    id='abc123'
    type='set'>
  <reminder xmlns='urn:xmpp:reminders:0'>
    <date>2020-02-19T23:41:00Z</date>
    <text xml:lang='en'>Please go sleep before it's too late</text>
  </reminder>
</iq>]]> </example>
	  <example caption='Server acknowledges the reminder creation'><![CDATA[
<iq id='abc123'
    to='juliet@capulet.net/balcony'
    from='capulet.net'
    type='result'>
  <reminder xmlns='urn:xmpp:reminders:0' id='d414cec2-5369-11ea-9455-8b8d265047d9'>
    <date>2020-02-19T23:41:00Z</date>
    <text xml:lang='en'>Please go sleep before it's too late</text>
  </reminder>
</iq>]]></example>
	  <p>Whenever the reminder's data sent by a client is not complete or
	  in an invalid format, the server MUST send an error stanza of type
	  'modify' and a 'bad-request' condition.</p>
	  <example caption='Server sends a bad-request error response'><![CDATA[
<iq id='bad1'
    to='capulet.net'
    from='juliet@capulet.net/balcony'
    type='set'>
  <reminder xmlns='urn:xmpp:reminders:0'>
    <date>Tomorrow at noon</date>
	<text xml:lang='en'>Lunch at Romeo's</text>
  </reminder>
</iq>

<iq id='bad1'
    to='juliet@capulet.net/balcony'
    from='capulet.net'
    type='error'>
  <error type='modify'>
    <bad-request xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>]]></example>
	  <p>In the event of a client trying to set a reminder in the
	  past, the server MUST send an error stanza of type 'modify' and
	  a 'gone' condition.</p>
	  <example caption='Server sends a gone error response'><![CDATA[
<iq id='bad2'
    to='capulet.net'
    from='juliet@capulet.net/balcony'
    type='set'>
  <reminder xmlns='urn:xmpp:reminders:0'>
    <date>2000-01-01T00:00:00Z</date>
    <text xml:lang='en'>New Year's party</text>
  </reminder>
</iq>

<iq id='bad2'
    to='juliet@capulet.net/balcony'
    from='capulet.net'
    type='error'>
  <error type='modify'>
    <gone xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>]]></example>
	</section2>
	<section2 topic='Server sends a reminder' anchor='send'>
	  <p>Whenever the time for a reminder arrives, the server MUST send
	  a message with the reminder to the creating entity.</p>
	  <example caption='Server sends a reminder'><![CDATA[
<message from='capulet.net' to='juliet@capulet.net/balcony' id='reminder1'>
  <reminder xmlns='urn:xmpp:reminders:0' id='d414cec2-5369-11ea-9455-8b8d265047d9'>
    <date timezone='UTC'>2020-02-19T23:41:00Z</date>
    <text xml:lang='en'>Please go sleep before it's too late</text>
  </reminder>
</message>]]></example> 
	  <p>After sending a reminder, the server MAY choose to delete it
	  from its storage.</p>
	</section2>
	<section2 topic='Client cancels a reminder' anchor='cancel'>
	  <p>There may be the case where a user wants to cancel an already
	  set reminder. To do so, the client MUST send an IQ stanza of
	  type 'set' with a 'reminder' child containing the 'id' attribute
	  of the reminder to be deleted, without any additional child.</p>
	  <example caption='Client deletes a reminder'><![CDATA[
<iq id='abc2'
    from='juliet@capulet.net/balcony'
    to='capulet.net'
    type='set'>
  <reminder xmlns='urn:xmpp:reminders:0' id='d414cec2-5369-11ea-9455-8b8d265047d9'/>
</iq>]]></example>
	  <example caption='Server acknowledges a reminder deletion'><![CDATA[
<iq id='abc2'
    to='juliet@capulet.net/balcony'
    from='capulet.net'
    type='result'>
  <reminder xmlns='urn:xmpp:reminders:0' id='d414cec2-5369-11ea-9455-8b8d265047d9'/>
</iq>]]></example>
	</section2>
  </section1>
  <section1 topic='Internationalization Considerations' anchor='i18n'>
	<p>As stated in the requirements, the 'date' element MUST contain
	a valid &xep0082; DateTime value.</p>
  </section1>
  <section1 topic='Security Considerations' anchor='security'>
	<p>This document introduces no additional security considerations
	above and beyond those defined in the documents on which it
	depends.</p>
  </section1>
  <section1 topic='IANA Considerations' anchor='iana'>
	<p>No interaction with &IANA; is required as a result of this document.</p>
  </section1>
  <section1 topic='XMPP Registrar Considerations' anchor='registrar'>
	<p>This specification defines the following XML namespace:</p>
	<ul>
	  <li>urn:xmpp:reminders:0</li>
	</ul>
	<p>Upon advancement of this specification from a status of
	Experimental to a status of Draft, the &REGISTRAR; shall add the
	foregoing namespace to the registry located at &NAMESPACES;, as
	described in Section 4 of &xep0053;.</p>
  </section1>
  <section1 topic='XML Schema' anchor='schema'>
	<p>TODO</p>
  </section1>
</xep>