git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@132 4b5297f7-1745-476d-ba37-a9c6900126ab
xep-0352-v0.2
Peter Saint-Andre 2006-10-30 22:13:49 +00:00
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@ -2,13 +2,13 @@
<!DOCTYPE xep SYSTEM 'xep.dtd' [
<!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
<!ENTITY ice11 "<cite>ICE-11</cite>">
<!ENTITY icecur "<cite>ICE-12</cite>">
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
<title>Jingle ICE Transport</title>
<abstract>This document defines a Jingle transport method that results in sending data between two entities using Interactive Connectivity Establishment (ICE) methodology.</abstract>
<abstract>This document defines a Jingle transport method that results in sending data between two entities using the Interactive Connectivity Establishment (ICE) methodology.</abstract>
&LEGALNOTICE;
<number>0176</number>
<status>Experimental</status>
@ -27,6 +27,12 @@
&scottlu;
&hildjj;
&seanegan;
<revision>
<version>0.5</version>
<date>2006-10-30</date>
<initials>psa</initials>
<remark><p>Updated to track ICE-12; corrected service discovery process; completed editorial review; removed mention of DTMF, which is for audio only.</p></remark>
</revision>
<revision>
<version>0.4</version>
<date>2006-09-13</date>
@ -53,15 +59,14 @@
</revision>
</header>
<section1 topic='Introduction' anchor='intro'>
<p>&xep0166; defines a framework for negotiating and managing out-of-band data sessions over XMPP. In order to provide a flexible framework, the base Jingle specification defines neither data transport methods nor content (session) types, leaving that up to separate specifications. The current document defines a transport method for establishing and managing data connections between XMPP entities, using the &ice; methodology currently being developed within the IETF.</p>
<p>The process for ICE negotiation is largely the same in Jingle as it is in draft-ietf-mmusic-ice. There are several differences:</p>
<p>&xep0166; defines a framework for negotiating and managing out-of-band data sessions over XMPP. In order to provide a flexible framework, the base Jingle specification defines neither data transport methods nor content formats, leaving that up to separate specifications. The current document defines a transport method for establishing and managing data connections between XMPP entities, using the &ice; methodology currently being developed within the IETF.</p>
<p>The process for ICE negotiation is largely the same in Jingle as it is in <cite>draft-ietf-mmusic-ice</cite>. There are several differences:</p>
<ul>
<li>Instead of using SIP as the signalling channel, Jingle uses XMPP as the signalling channel.</li>
<li>In Jingle, each candidate transport is sent in a separate IQ exchange (rather than sending all candidates at once as in draft-ietf-mmusic-ice); this approach takes advantage of the request-response semantics of the XMPP &IQ; stanza type and enables the parties to send higher-priority candidates earlier in the negotiation.</li>
<li>In Jingle, each candidate transport is sent in a separate IQ exchange (rather than sending all candidates at once as in <cite>draft-ietf-mmusic-ice</cite>); this approach takes advantage of the request-response semantics of the XMPP &IQ; stanza type and enables the parties to send higher-priority candidates earlier in the negotiation.</li>
<li>Syntax from the Session Description Protocol (see &rfc4566;) is mapped to an XML syntax suitable for sending over the XMPP signalling channel.</li>
</ul>
<p><em>Note: This document depends on the IETF's Interactive Connectivity Establishment (ICE) specification, which is a work in progress. Every effort has been made to keep this document synchronized with draft-ietf-mmusic-ice, for which the latest published version is 11 (hereafter referred to as "&ice11;"). The interested reader is referred to the &ice11; for a detailed description of the ICE methodology, which for the most part this document merely maps to XMPP syntax.</em></p>
<p><em>Note: This document still needs to be updated to track the changes between ICE-10 and ICE-11. That work will be completed as soon as possible.</em></p>
<p><em>Note: This document depends on the IETF's Interactive Connectivity Establishment (ICE) specification, which is a work in progress. Every effort has been made to keep this document synchronized with <cite>draft-ietf-mmusic-ice</cite>, for which the latest published version is 12 (hereafter referred to as "&icecur;"). The interested reader is referred to the &icecur; for a detailed description of the ICE methodology, which for the most part this document merely maps to XMPP syntax.</em></p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
<p>The Jingle transport method defined herein is designed to meet the following requirements:</p>
@ -72,7 +77,7 @@
</ol>
</section1>
<section1 topic='Glossary' anchor='terms'>
<p>The reader is referred to draft-ietf-mmusic-ice for a description of various terms used in the context of ICE. Those terms are not reproduced here.</p>
<p>The reader is referred to &icecur; for a description of various terms used in the context of ICE. Those terms are not reproduced here.</p>
</section1>
<section1 topic='Protocol Description' anchor='protocol'>
<section2 topic='Transport Initiation' anchor='protocol-initiate'>
@ -88,17 +93,14 @@
...
</description>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'/>
<transport xmlns='http://jabber.org/protocol/jingle/transport/raw-udp'>
...
</transport>
</content>
</jingle>
</iq>
]]></example>
</section2>
<section2 topic='Target Entity Response' anchor='protocol-response'>
<section2 topic='Receiver Response' anchor='protocol-response'>
<p>As described in <cite>XEP-0166</cite>, to provisionally accept the session initiation request, the responder returns an IQ-result:</p>
<example caption="Target Entity Provisionally Accepts the Session Request"><![CDATA[
<example caption="Receiver Provisionally Accepts the Session Request"><![CDATA[
<iq type='result' from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='jingle1'/>
]]></example>
</section2>
@ -139,13 +141,13 @@
</tr>
<tr>
<td>component</td>
<td>A Component ID as defined in &ice11;</td>
<td>A Component ID as defined in &icecur;</td>
<td>Component ID value in a=candidate line</td>
<td>1</td>
</tr>
<tr>
<td>foundation</td>
<td>A Foundation as defined in &ice11;</td>
<td>A Foundation as defined in &icecur;</td>
<td>Foundation value in a=candidate line</td>
<td>1</td>
</tr>
@ -175,43 +177,43 @@
</tr>
<tr>
<td>priority</td>
<td>A Priority as defined in &ice11;</td>
<td>A Priority as defined in &icecur;</td>
<td>Priority value in a=candidate line</td>
<td>9909</td>
</tr>
<tr>
<td>protocol</td>
<td>The protocol to be used; allowable values are: "udp" (when standard &ice11; is used); "tcp", "tcp-act", and "tcp-pass" (when &ice-tcp; is used); and "ssltcp" (definition to follow)</td>
<td>a=ice-ufrag line</td>
<td>The protocol to be used; allowable values are: "udp" (when standard &icecur; is used); "tcp", "tcp-act", and "tcp-pass" (when &ice-tcp; is used); and "ssltcp" (definition to follow)</td>
<td>Transport protocol field in a=candidate line</td>
<td>udp</td>
</tr>
<tr>
<td>pwd</td>
<td>A Password as defined in &ice11;</td>
<td>A Password as defined in &icecur;</td>
<td>a=ice-pwd line</td>
<td>asd88fgpdd777uzjYhagZg</td>
</tr>
<tr>
<td>type</td>
<td>A Candidate Type as defined in &ice11;; the allowable values are "host" for host candidates, "srflx" for server reflexive candidates, "prflx" for peer reflexive candidates, and "relay" for relayed candidates</td>
<td>A Candidate Type as defined in &icecur;; the allowable values are "host" for host candidates, "srflx" for server reflexive candidates, "prflx" for peer reflexive candidates, and "relay" for relayed candidates</td>
<td>Typ field in a=candidate line</td>
<td>srflx</td>
</tr>
<tr>
<td>ufrag</td>
<td>A User Fragment as defined in &ice11;</td>
<td>A User Fragment as defined in &icecur;</td>
<td>a=ice-ufrag line</td>
<td>8hhy</td>
</tr>
</table>
</section3>
<section3 topic='Negotiation Flow' anchor='protocol-negotiate-flow'>
<p>The first step in negotiating connectivity is for each client to immediately begin sending candidate transport methods to the other client. These candidates SHOULD be gathered by following the procedure specified in Section 4.1 of &ice11; and prioritized by following the procedure specified in Section 4.2 of &ice11;. Each candidate MUST be sent in a &JINGLE; element with an action of "transport-info".</p>
<p>The first step in negotiating connectivity is for each client to immediately begin sending candidate transport methods to the other client. These candidates SHOULD be gathered by following the procedure specified in Section 5.1 of &icecur; and prioritized by following the procedure specified in Section 5.2 of &icecur;. Each candidate MUST be sent in a &JINGLE; element with an action of "transport-info".</p>
<p>If the responder receives and can successfully process a given candidate, it returns an IQ-result (if not, for example because the candidate data is improperly formatted, it returns an error).</p>
<p>Note well that the responder is only indicating receipt of the candidate, not telling the initiator that the candidate will be used.</p>
<p>The initiator keeps sending candidates, one after the other (without stopping to receive an acknowledgement of receipt from the responder for each candidate) until it has exhausted its supply of possible or desirable candidate transports. (Because certain candidates may be more "expensive" in terms of bandwidth or processing power, the initiator may not want to advertise their existence unless necessary.) For each candidate, the responder acknowledges receipt.</p>
<p>At the same time (i.e., immediately after provisionally accepting the session, not waiting for the initiator to begin or finish sending candidates), the responder also begins sending candidates that may work for it. As above, the initiator acknowledges receipt of the candidates.</p>
<p>As the initiator and responder receive candidates, they probe the various candidate transports for connectivity. In performing these connectivity checks, client SHOULD follow the procedure specified in Section 7 of &ice11;.</p>
<p>As the initiator and responder receive candidates, they probe the various candidate transports for connectivity. In performing these connectivity checks, client SHOULD follow the procedure specified in Section 7 of &icecur;.</p>
<example caption="Initiating Entity Sends a Candidate"><![CDATA[
<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='info1' type='set'>
<jingle xmlns='http://jabber.org/protocol/jingle'
@ -319,9 +321,9 @@
<iq type='result' to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='accept1'/>
]]></example>
<p>Now the initiator and responder can begin sending data over the negotiated connection.</p>
<p>If a candidate succeeeded for the responder but the initiator cannot send data over that candidate, it MUST return a &notacceptable; error in response to the responder's acceptance of the successful candidate:</p>
<p>If a candidate succeeded for the responder but the initiator cannot send data over that candidate, it MUST return a &notacceptable; error in response to the responder's acceptance of the successful candidate:</p>
<example caption="Romeo Returns Error in Response to Acceptance of Successful Candidate"><![CDATA[
<iq type='errror' to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='accept1'>
<iq type='error' to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='accept1'>
<jingle xmlns='http://jabber.org/protocol/jingle'
action='transport-accept'
initiator='romeo@montague.net/orchard'
@ -346,41 +348,21 @@
</error>
</iq>
]]></example>
<p>If the responder cannot find a suitable candidate transport or it receives a &notacceptable; errror from the initiator in response to its acceptance of a suitable transport, it SHOULD terminate the session as described below.</p>
</section2>
<section2 topic='Termination' anchor='protocol-terminate'>
<p>In order to gracefully end the session, either the responder or the initiator MUST a send a "terminate" action to the other party:</p>
<example caption="Juliet Terminates the Session"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='term1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://jabber.org/protocol/jingle'
action='terminate'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'/>
</iq>
]]></example>
<p>The initiator then acknowledges termination of the session:</p>
<example caption="Romeo Acknowledges Termination"><![CDATA[
<iq type='result' to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='term1'/>
]]></example>
<p>Unfortunately, not all sessions end gracefully. The following events MUST be considered session-ending events, and any further communication for the session type MUST be completed through negotiation of a new session:</p>
<ul>
<li>Receipt of a 'redirect' or 'terminate' action from the other party.</li>
<li>Receipt of &UNAVAILABLE; from the other party.</li>
</ul>
<p>In particular, one party MUST consider the session to be in the ENDED state if it receives presence of type "unavailable" from the other party:</p>
<example caption="Juliet Goes Offline"><![CDATA[
<presence from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' type='unavailable'/>
]]></example>
<p>Naturally, in this case there is nothing for the initiator to acknowledge.</p>
<p>If the responder cannot find a suitable candidate transport or it receives a &notacceptable; error from the initiator in response to its acceptance of a suitable transport, it SHOULD terminate the session as described in Section 5.9 of <cite>XEP-0166</cite>.</p>
</section2>
</section1>
<section1 topic='Service Discovery' anchor='disco'>
<p>If an entity supports this specification, it MUST return a feature of "http://jabber.org/protocol/jingle/transport/ice" in response to &xep0030; information requests.</p>
<p>As mentioned in the <link url='#deploy'>Deployment Notes</link> of this document, server administrators may wish to deploy STUN servers in order to ease the process of negotiating use of the Jingle ICE transport. If a STUN server is accessible via XMPP, it SHOULD be advertised by returning an appropriate item in response to service discovery item requests sent to the address of an XMPP server:</p>
<p>As mentioned in the <link url='#deploy'>Deployment Notes</link> of this document, the administrator of an XMPP server may wish to deploy a STUN server in order to ease the process of negotiating use of the Jingle ICE transport. A client can become aware of a STUN server in the following ways:</p>
<ol start='1'>
<li>Specified in the default settings for the client (while this may seem sub-optimal, it is acceptable at present because there are so few public STUN servers).</li>
<li>Manually added by a human user into the client's configuration.</li>
<li>Discovered via DNS SRV records as specified in Section 9.1 of &rfc3489;.</li>
<li>Discovered via the XMPP &xep0030; extension.</li>
</ol>
<p>It is OPTIONAL for a STUN server to support XMPP for the purpose of service discovery. Therefore, client developers SHOULD NOT depend on the existence of XMPP-aware STUN servers.</p>
<p>If a STUN server is accessible via XMPP, it SHOULD be advertised by returning an appropriate item in response to service discovery item requests sent to the address of an XMPP server:</p>
<example caption="Service Discovery of STUN Server (1)"><![CDATA[
<iq from='romeo@montague.net/orchard' to='montague.net' id='disco1' type='get'>
<query xmlns='http://jabber.org/protocol/disco#items'/>
@ -392,7 +374,7 @@
</query>
</iq>
]]></example>
<p>A subsequent service discovery information request to the STUN server MUST result in a response indicating that the STUN server has a service discovery category of "proxy" and type of "stun":</p>
<p>A subsequent service discovery information request to the STUN server MUST result in a response indicating that the STUN server has a service discovery category of "proxy" and type of "stun", as well as advertisement of appropriate service discovery features (because the XMPP interaction is necessary only in order to discover the identity of the STUN server, the only feature that an XMPP-aware STUN server SHOULD advertise is "http://jabber.org/protocol/disco#info".)</p>
<example caption="Service Discovery of STUN Server (2)"><![CDATA[
<iq from='romeo@montague.net/orchard' to='stun.montague.net' id='disco2' type='get'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
@ -405,14 +387,6 @@
</query>
</iq>
]]></example>
<p>Because the XMPP interaction is necessary only in order to discover the identity of the STUN server, only support for the "http://jabber.org/protocol/disco#info" feature is RECOMMEND.</p>
<p>It is OPTIONAL for a STUN server to support XMPP, and STUN servers may be configured into an XMPP client via other means (e.g., user configuration or default settings). Client developers SHOULD NOT depend on the existence of XMPP-aware STUN servers.</p>
</section1>
<section1 topic='Implementation Notes' anchor='impl'>
<section2 topic='DTMF' anchor='impl-dtmf'>
<p>If it is necessary to send Dual Tone Multi-Frequency (DTMF) tones, it is REQUIRED to use the XML format specified &xep0181;.</p>
</section2>
</section1>
<section1 topic='Deployment Notes' anchor='deploy'>
@ -435,13 +409,13 @@
</section2>
<section2 topic='Jingle Transport Methods' anchor='registrar-transports'>
<p>The XMPP Registrar shall include "http://jabber.org/protocol/jingle/transport/ice" in its registry of Jingle transport methods. The registry submission is as follows:</p>
&REGPROCESS;
<code><![CDATA[
<transport>
<name>ice</name>
<desc>
A method for negotiation of out-of-band connections with built-in NAT and firewall traversal,
similar to the IETF's Interactive Connectivity Establishment (ICE) methodology.
A method for negotiation of out-of-band connections with built-in NAT and firewall
traversal, equivalent to the IETF's Interactive Connectivity Establishment (ICE)
methodology.
</desc>
<doc>XEP-0176</doc>
</transport>
@ -494,6 +468,17 @@
<xs:attribute name='network' type='xs:unsignedByte' use='required'/>
<xs:attribute name='port' type='xs:unsignedShort' use='required'/>
<xs:attribute name='priority' type='xs:positiveInteger' use='required'/>
<xs:attribute name='protocol' use='optional'>
<xs:simpleType>
<xs:restriction base='xs:NCName'>
<xs:enumeration value='ssltcp'/>
<xs:enumeration value='tcp-act'/>
<xs:enumeration value='tcp-pass'/>
<xs:enumeration value='tcp'/>
<xs:enumeration value='udp'/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name='pwd' type='xs:string' use='required'/>
<xs:attribute name='type' use='optional'>
<xs:simpleType>