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xep-0176.xml
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@ -2,7 +2,7 @@
<!DOCTYPE xep SYSTEM 'xep.dtd' [
<!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
<!ENTITY icecur "<cite>ICE-12</cite>">
<!ENTITY icecurr "<cite>ICE-12</cite>">
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
@ -21,52 +21,58 @@
</dependencies>
<supersedes/>
<supersededby/>
<shortname>ice</shortname>
<shortname>TO BE ASSIGNED</shortname>
&stpeter;
&joebeda;
&scottlu;
&hildjj;
&seanegan;
<revision>
<version>0.6</version>
<date>2006-12-21</date>
<initials>psa</initials>
<remark><p>Modified spec to use provisional namespace before advancement to Draft (per XEP-0053).</p></remark>
</revision>
<revision>
<version>0.5</version>
<date>2006-10-31</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>
<remark><p><p>Updated to track ICE-12; corrected service discovery process; completed editorial review; removed mention of DTMF, which is for audio only.</p></p></remark>
</revision>
<revision>
<version>0.4</version>
<date>2006-09-13</date>
<initials>psa</initials>
<remark><p>Updated to track ICE-10; added section on service discovery.</p></remark>
<remark><p><p>Updated to track ICE-10; added section on service discovery.</p></p></remark>
</revision>
<revision>
<version>0.3</version>
<date>2006-07-12</date>
<initials>se/psa</initials>
<remark><p>Specified that DTMF must use in-band signalling (XEP-0181).</p></remark>
<remark><p><p>Specified that DTMF must use in-band signalling (XEP-0181).</p></p></remark>
</revision>
<revision>
<version>0.2</version>
<date>2006-03-24</date>
<initials>psa</initials>
<remark><p>Recommended use of RTP-native methods for DTMF.</p></remark>
<remark><p><p>Recommended use of RTP-native methods for DTMF.</p></p></remark>
</revision>
<revision>
<version>0.1</version>
<date>2006-03-01</date>
<initials>psa/jb</initials>
<remark>Initial version (split from XEP-0166).</remark>
<remark><p>Initial version (split from XEP-0166).</p></remark>
</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 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>
<p><em>Note: This document depends on the IETF's &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 "&icecurr;"). The interested reader is referred to the &icecurr; for a detailed description of the ICE methodology, which for the most part this document merely maps to XMPP syntax.</em></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 &icecurr;. 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 <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>In Jingle, each candidate transport is sent in a separate IQ exchange (rather than sending all candidates at once as in &icecurr;); 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 <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>
@ -77,22 +83,22 @@
</ol>
</section1>
<section1 topic='Glossary' anchor='terms'>
<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>
<p>The reader is referred to &icecurr; 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'>
<p>In order for the initiator in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in <cite>XEP-0166</cite>. This stanza MUST include at least one transport method. If the initiator wishes to negotiate the ICE transport, it MUST include an empty &TRANSPORT; child element qualified by the 'http://jabber.org/protocol/jingle/transport/ice' namespace.</p>
<p>In order for the initiator in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in <cite>XEP-0166</cite>. This stanza MUST include at least one transport method. If the initiator wishes to negotiate the ICE transport, it MUST include an empty &TRANSPORT; child element qualified by the 'http://www.xmpp.org/extensions/xep-0176.html#ns' namespace (see <link url='#ns'>Protocol Namespaces</link>).</p>
<example caption="Initiation"><![CDATA[
<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='jingle1' type='set'>
<jingle xmlns='http://jabber.org/protocol/jingle'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-initiate'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content name='this-is-the-audio-content'>
<description xmlns='http://jabber.org/protocol/jingle/description/audio'>
<description xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns/description/audio'>
...
</description>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'/>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'/>
</content>
</jingle>
</iq>
@ -111,11 +117,11 @@
<p>The following is an example of the candidate format:</p>
<example caption="Initiating Entity Sends a Candidate Transport"><![CDATA[
<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='info1' type='set'>
<jingle xmlns='http://jabber.org/protocol/jingle'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-info'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -141,13 +147,13 @@
</tr>
<tr>
<td>component</td>
<td>A Component ID as defined in &icecur;</td>
<td>A Component ID as defined in &icecurr;</td>
<td>Component ID value in a=candidate line</td>
<td>1</td>
</tr>
<tr>
<td>foundation</td>
<td>A Foundation as defined in &icecur;</td>
<td>A Foundation as defined in &icecurr;</td>
<td>Foundation value in a=candidate line</td>
<td>1</td>
</tr>
@ -177,52 +183,52 @@
</tr>
<tr>
<td>priority</td>
<td>A Priority as defined in &icecur;
<note>In accordance with the rules specified in Section 5.2 of &icecur;, the priority values shown in the examples within this document have been calculated as follows. The "type preference" for local candidates is stipulated to be "126" and for server reflexive candidates "66". The "local preference" for network 0 is stipulated to be "4096", for network 1 "2048", and for network 2 "1024".</note>
<td>A Priority as defined in &icecurr;
<note>In accordance with the rules specified in Section 5.2 of &icecurr;, the priority values shown in the examples within this document have been calculated as follows. The "type preference" for local candidates is stipulated to be "126" and for server reflexive candidates "66". The "local preference" for network 0 is stipulated to be "4096", for network 1 "2048", and for network 2 "1024".</note>
</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 &icecur; is used); "tcp", "tcp-act", and "tcp-pass" (when &ice-tcp; is used); and "ssltcp" (definition to follow)</td>
<td>The protocol to be used; allowable values are: "udp" (when standard &icecurr; 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 &icecur;</td>
<td>A Password as defined in &icecurr;</td>
<td>a=ice-pwd line</td>
<td>asd88fgpdd777uzjYhagZg</td>
</tr>
<tr>
<td>type</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>A Candidate Type as defined in &icecurr;; 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 &icecur;</td>
<td>A User Fragment as defined in &icecurr;</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 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>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 &icecurr; and prioritized by following the procedure specified in Section 5.2 of &icecurr;. 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 &icecur;.</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 &icecurr;.</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'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-info'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -240,11 +246,11 @@
]]></example>
<example caption="Initiating Entity Sends a Second Candidate"><![CDATA[
<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='info2' type='set'>
<jingle xmlns='http://jabber.org/protocol/jingle'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-info'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='2'
foundation='1'
generation='0'
@ -262,11 +268,11 @@
]]></example>
<example caption="Initiating Entity Sends a Third Candidate"><![CDATA[
<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='info3' type='set'>
<jingle xmlns='http://jabber.org/protocol/jingle'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-info'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='2'
foundation='1'
generation='0'
@ -296,12 +302,12 @@
<p>If, based on STUN connectivity checks, the responder determines that it will be able to establish a connection using a given candidate, it sends a &JINGLE; element with an action of 'transport-accept' to the initiator, specifying the candidate that succeeded:</p>
<example caption="Juliet Definitively Accepts the Successful Candidate"><![CDATA[
<iq type='set' from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='accept1'>
<jingle xmlns='http://jabber.org/protocol/jingle'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-accept'
initiator='romeo@montague.net/orchard'
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='2'
foundation='1'
generation='0'
@ -326,12 +332,12 @@
<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='error' to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='accept1'>
<jingle xmlns='http://jabber.org/protocol/jingle'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-accept'
initiator='romeo@montague.net/orchard'
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<transport xmlns='http://jabber.org/protocol/jingle/transport/ice'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='2'
foundation='1'
generation='0'
@ -355,7 +361,7 @@
</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>If an entity supports this specification, it MUST return a feature of "http://www.xmpp.org/extensions/xep-0176.html#ns" in response to &xep0030; information requests.</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>
@ -406,11 +412,11 @@
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
<section2 topic='Protocol Namespaces' anchor='registrar-ns'>
<p>The &REGISTRAR; shall include 'http://jabber.org/protocol/jingle/transport/ice' in its registry of protocol namespaces.</p>
<section2 topic='Protocol Namespaces' anchor='ns'>
<p>Until this specification advances to a status of Draft, its associated namespace shall be "http://www.xmpp.org/extensions/xep-0176.html#ns"; upon advancement of this specification, the &REGISTRAR; shall issue a permanent namespace in accordance with the process defined in Section 4 of &xep0053;.</p>
</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>
<p>The XMPP Registrar shall include "ice" in its registry of Jingle transport methods. The registry submission is as follows:</p>
<code><![CDATA[
<transport>
<name>ice</name>
@ -445,8 +451,8 @@
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='http://jabber.org/protocol/jingle/transport/ice'
xmlns='http://jabber.org/protocol/jingle/transport/ice'
targetNamespace='http://www.xmpp.org/extensions/xep-0176.html#ns'
xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'
elementFormDefault='qualified'>
<xs:element name='transport'>