Merge branch 'feature/xep-0410'

xep-0410.xml

@@ -29,6 +29,12 @@
     <email>georg@op-co.de</email>
     <jid>georg@yax.im</jid>
   </author>
+  <revision>
+    <version>0.2.0</version>
+    <date>2019-02-04</date>
+    <initials>gl</initials>
+    <remark>Incorporate feedback from Last Call.</remark>
+  </revision>
   <revision>
     <version>0.1.0</version>
     <date>2018-08-31</date>
@@ -53,15 +59,16 @@
     not designed to handle s2s interruptions or message loss well.  Rather
     often, the restart of a server or a component causes a client to believe
     that it is still joined to a given chatroom, while the chatroom service
-    does not know of this participant.</p>
+    does not know of this occupant.</p>
   <p>Existing approaches for re-synchronization are either inefficient
-    (presence updates and "silent" messages are reflected to all participants,
+    (presence updates and "silent" messages are reflected to all occupants,
     totalling to O(N²) stanzas per time unit), or mask message /
     presence losses (the implicit join performed via the deprecated GC1.0
     protocol).</p>
   <p>This specification aims to provide the most efficient, albeit not the
     most elegant, way for clients to periodically check whether they are still
-    joined to a chatroom.</p>
+    joined to a chatroom. However, it can not ensure that a client remains
+    joined to a room without any interruptions.</p>
 </section1>
 <section1 topic='Requirements' anchor='reqs'>
   <p>This specification only makes sense in the context of &xep0045;
@@ -75,8 +82,8 @@
     and a typically local server-to-component link. If one of the involved
     servers or the MUC component is restarted, or one of the links is
     disturbed for some time, this can lead to the removal of some or all
-    participants from the affected MUCs, without the clients being informed.</p>
+    occupants from the affected MUCs, without the clients being informed.</p>
-  <p>To a participant, this looks like the MUC is silent (there is no chat
+  <p>To an occupant, this looks like the MUC is silent (there is no chat
     activity and no presence changes), making it hard to realize that the
     connection was interrupted.</p>
   <p>To prevent the bad usability effect (message loss, lack of reaction from
@@ -87,13 +94,13 @@
       it is still joined to a MUC:</p>
     <ol>
       <li><strong>Silent message</strong> (e.g. &xep0085;): this message will be reflected to
-	all MUC participants, causing unwanted traffic and potentially waking
+	all MUC occupants, causing unwanted traffic and potentially waking
         up mobile devices without reason. If implemented by all clients, this
 	will result in O(N²) messages to the MUC.</li>
       <li><strong>Presence update</strong>: if the MUC service implements the legacy GC1.0 protocol,
 	this will be treated as a join attempt, and the MUC will return the
-	full list of participants and full room history. The user's client
+	full list of occupants and full room history. The user's client
-	will however miss partial history (other participants leaving,
+	will however miss partial history (other occupants leaving,
 	potentially also messages), and this has the same drawbacks as the
 	first solution.</li>
       <li><strong>Private message to self</strong>: the client can send a MUC
@@ -101,7 +108,7 @@
 	private messages, and there is no way to differentiate that from the
 	error responses.</li>
       <li><strong>Private IQ to self</strong>: the client can send an IQ to
-	its own participant JID. MUCs typically do not forbid those, and
+	its own occupant JID. MUCs typically do not forbid those, and
 	reflect the IQ request to the client (or another client of the same
 	user). Once that client responds to the reflected IQ, the response is
 	delivered to the initiating client as a sign of still being joined.
@@ -130,7 +137,7 @@
     <p>If Juliet's client is not joined, the MUC service will respond with a
       &lt;not-acceptable&gt; error. Thus, her client can automatically attempt
       a rejoin.</p>
-    <example caption="Server Response to a Non-Participant"><![CDATA[
+    <example caption="Server Response to a Non-Occupant"><![CDATA[
 <iq from='characters@chat.shakespeare.lit/JuliC' id='s2c1' type='error'
       to='juliet@capulet.lit/client' >
   <error type="cancel">
@@ -155,10 +162,14 @@
 	  &lt;feature-not-implemented&gt;)</strong>: the client is joined, but
 	the pinged client does not implement &xep0199;.</li>
       <li><strong>Error (&lt;item-not-found&gt;)</strong>: the client is
-	joined, but the participant just changed their name (e.g. initiated by
+	joined, but the occupant just changed their name (e.g. initiated by
 	a different client).</li>
-      <li><strong>Any other error</strong>: the client is probably not
+      <li><strong>Any other error</strong><note>Different service
-	joined.</li>
+	  implementations will send different responses to a client that's not
+	  joined. The recommended error code is &lt;not-acceptable&gt;, however
+	  some servers will respond with &lt;not-allowed&gt; or
+	  &lt;bad-request&gt; as well.</note>: the client is probably not
+	joined any more. It should perform a re-join.</li>
       <li><strong>Timeout (no response)</strong>: the MUC service (or another
 	client) is unreachable. The client may indicate the status to the user
 	and re-attempt the self-ping after some timeout, until it receives
@@ -173,32 +184,61 @@
       connectivity issues, which is often the case with mobile devices, the
       ping request might never be responded to.</p>
     <p>Therefore, a MUC service supporting this protocol may directly respond
-      to a participant's Ping request to the participant's own nickname, as
+      to a occupant's Ping request to the occupant's own nickname, as
-      opposed to routing it to any of the participant's clients.</p>
+      opposed to routing it to any of the occupant's clients. A service
+      implementing this optimization needs to advertise the
+      <tt>self-ping-optimization</tt> feature in the &xep0030; response on
+      the individual MUC room JIDs, and it MUST respond to a self-ping request
+      as follows:</p>
+    <ul>
+      <li><strong>Successful IQ response</strong>: the client is joined to the MUC.</li>
+      <li><strong>Error (&lt;not-acceptable&gt;)</strong>: the client is not joined to the MUC.</li>
+    </ul>
+<example caption='MUC Service Advertises Self-Ping Optimization'><![CDATA[
+<iq from='darkcave@chat.shakespeare.lit'
+    type='result'>
+  <query xmlns='http://jabber.org/protocol/disco#info'>
+    <!-- ... -->
+    <feature var='http://jabber.org/protocol/muc#self-ping-optimization'/>
+  </query>
+</iq>
+]]></example>
   </section2>
 </section1>
 <section1 topic='Implementation Notes' anchor='impl'>
   <p>In Multi-Session-Nick scenarios, where multiple clients of the same user
-    are joined as the same participant, it is possible that another client
+    are joined as the same occupant, it is possible that another client
     initiates a nickname change while a ping request is pending. In that case,
     the ping might be responded to with &lt;item-not-found&gt;.</p>
   <p>A client should not perform a self-ping after initiating a nickname
     change, and before receiving the response to the nickname change from the
     service, as it is not yet clear whether the new nickname will be accepted.
   </p>
+  <p>If a client session is in hibernation (&xep0198;), the client should defer
+    sending of self-ping requests until it is reconnected and re-authenticated.
+  </p>
 </section1>
 <section1 topic='Security Considerations' anchor='security'>
-  <p>A MUC service implementation should not allow a non-participant to obtain
+  <p>A MUC service implementation should not allow a non-occupant to obtain
-    information about participants. This is however true irregardless of
+    information about occupants. This is however true irregardless of
     implementing this specification.</p>
 </section1>
 <section1 topic='IANA Considerations' anchor='iana'>
-  <p>REQUIRED.</p>
+  <p>This document requires no interaction with &IANA;.</p>
 </section1>
 <section1 topic='XMPP Registrar Considerations' anchor='registrar'>
-  <p>REQUIRED.</p>
+  <p>Include "<tt>http://jabber.org/protocol/muc#self-ping-optimization</tt>"
+    as a valid feature in the Registry of Features.</p>
+    <code caption='Registry Submission'><![CDATA[
+<var>
+  <name>http://jabber.org/protocol/muc#self-ping-optimization</name>
+  <desc>Support for the MUC self-ping optimization</desc>
+  <doc>XEP-0410</doc>
+</var>
+]]></code>
+
 </section1>
 <section1 topic='XML Schema' anchor='schema'>
-  <p>REQUIRED for protocol specifications.</p>
+  <p>This document does not define any new XML structure requiring a schema.</p>
 </section1>
 </xep>