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Merge branch 'feature/xep-0410'

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Jonas Schäfer 2019-02-04 17:12:39 +01:00
parent 75fc8a5c81 b21b3504b5
commit b28208e3aa
1 changed files with 61 additions and 21 deletions
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xep-0410.xml
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@ -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>
<p>To a participant, this looks like the MUC is silent (there is no chat
occupants from the affected MUCs, without the clients being informed.</p>
<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
will however miss partial history (other participants leaving,
full list of occupants and full room history. The user's client
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
joined.</li>
<li><strong>Any other error</strong><note>Different service
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
opposed to routing it to any of the participant's clients.</p>
to a occupant's Ping request to the occupant's own nickname, as
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
information about participants. This is however true irregardless of
<p>A MUC service implementation should not allow a non-occupant to obtain
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>