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xep-0176.xml
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@ -8,7 +8,7 @@
<?xml-stylesheet type='text/xsl' href='xep.xsl'?> <?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep> <xep>
<header> <header>
<title>Jingle ICE Transport</title> <title>Jingle ICE Transport Methods</title>
<abstract>This document defines a Jingle transport method that results in sending data between two entities using the 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; &LEGALNOTICE;
<number>0176</number> <number>0176</number>
@ -28,6 +28,12 @@
&scottlu; &scottlu;
&hildjj; &hildjj;
&seanegan; &seanegan;
<revision>
<version>0.11</version>
<date>2007-11-27</date>
<initials>psa</initials>
<remark><p>Further editorial review; also added sections on modification of existing candidates and exchange of subsequent candidates.</p></remark>
</revision>
<revision> <revision>
<version>0.10</version> <version>0.10</version>
<date>2007-11-15</date> <date>2007-11-15</date>
@ -90,14 +96,20 @@
</revision> </revision>
</header> </header>
<section1 topic='Introduction' anchor='intro'> <section1 topic='Introduction' anchor='intro'>
<p><em>Note: This document depends on the IETF's specifications for &ice; and &ice-tcp; (the former has been approved but the latter is still a work in progress). Every effort has been made to keep this document synchronized with <cite>draft-ietf-mmusic-ice</cite> and <cite>draft-ietf-mmusic-ice-tcp</cite>. The interested reader is referred to &icecore; 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 application formats, leaving that up to separate specifications. The current document defines two transport methods for establishing and managing data connections between XMPP entities, using the ICE methodology developed within the IETF:</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 application formats, leaving that up to separate specifications. The current document defines two transport methods (ice-udp and ice-tcp) for establishing and managing data connections between XMPP entities, using the ICE methodology developed within the IETF. The ice-udp method results in a lossy transport suitable for use in media applications where some packet loss is tolerable (e.g., audio and video), whereas the ice-tcp method results in a reliable transport suitable for use in applications where packet loss is not tolerable (e.g., file transfer).</p> <ol>
<li><p>The <strong>ice-udp</strong> method is an XMPP profile of the core ICE methodology specified in &ice;. The IETF specification in question, hereafter referred to as &icecore;, has been approved for publication as an RFC but has not yet been so published. Use of the ice-udp method results in a lossy transport suitable for media applications where some packet loss is tolerable (e.g., audio and video).</p></li>
<li><p>The <strong>ice-tcp</strong> method is an XMPP profile of the ICE methodology as applied to TCP and specified in &ice-tcp;, hereafter referred to as &icetcp;. The IETF specification in question is still a work in progress. Use of the ice-tcp method results in a reliable transport suitable applications where packet loss is not tolerable (e.g., file transfer).</p></li>
</ol>
<p>The process for ICE negotiation is largely the same in Jingle as it is in ICE. There are several differences:</p> <p>The process for ICE negotiation is largely the same in Jingle as it is in ICE. There are several differences:</p>
<ul> <ul>
<li>Instead of using SIP as the signalling channel, Jingle uses XMPP as the signalling channel.</li> <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 &icecore;). <note>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, but implies that Jingle is not exactly an offer-answer protocol as specified in RFC 3264.</note></li> <li>In Jingle, each candidate transport is sent in a separate IQ exchange (rather than sending all candidates at once as in &icecore;). <note>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, but implies that Jingle is not exactly an offer-answer protocol as specified in RFC 3264.</note></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> <li>Syntax from the Session Description Protocol (see &rfc4566;) is mapped to an XML syntax suitable for sending over the XMPP signalling channel.</li>
<li>ICE candidates can be upgraded during a session (e.g., to change an IP address).</li>
<li>Either party can continue to send ICE candidates throughout a session and renegotiate which candidate will be used.</li>
</ul> </ul>
<p><em>Note: This document depends the &icecore; and &icetcp; specifications developed by the IETF. While every effort has been made to keep this document synchronized with &icecore; and &icetcp;, the interested reader is referred to &icecore; for a detailed description of the ICE methodology.</em></p>
</section1> </section1>
<section1 topic='Glossary' anchor='terms'> <section1 topic='Glossary' anchor='terms'>
<p>The reader is referred to &icecore; and &icetcp; 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 &icecore; and &icetcp; for a description of various terms used in the context of ICE. Those terms are not reproduced here.</p>
@ -142,9 +154,9 @@
</iq> </iq>
]]></example> ]]></example>
</section2> </section2>
<section2 topic='Receiver Response' anchor='protocol-response'> <section2 topic='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> <p>As described in <cite>XEP-0166</cite>, to acknowledge receipt of the session initiation request, the responder returns an IQ-result:</p>
<example caption="Receiver provisionally accepts the session request"><![CDATA[ <example caption="Responder acknowledges receipt of session-initiate request"><![CDATA[
<iq from='juliet@capulet.com/balcony' <iq from='juliet@capulet.com/balcony'
id='jingle1' id='jingle1'
to='romeo@montague.net/orchard' to='romeo@montague.net/orchard'
@ -152,37 +164,23 @@
]]></example> ]]></example>
</section2> </section2>
<section2 topic='ICE Negotiation' anchor='protocol-negotiate'> <section2 topic='ICE Negotiation' anchor='protocol-negotiate'>
<p>If the responder provisionally accepts the session initiation request as shown above, both initiator and responder MUST immediately negotiate connectivity over the ICE transport by exchanging XML-formatted candidate transports for the channel. This negotiation proceeds immediately in order to maximize the possibility that media can be exchanged as quickly as possible. <note>Concurrent with negotiation of the ICE candidates, it is possible for the initiator and responder to negotiate which content types the session will include, which transport methods will be tried for each content type, etc. Those negotiation flows are shown in <cite>XEP-0166</cite>. This document specifies only negotiation of the ICE transport method.</note></p> <p>Once the responder acknowledges receipt of the session initiation request as shown above, both initiator and responder MUST immediately negotiate connectivity over the ICE transport by exchanging XML-formatted candidate transports for the channel. This negotiation proceeds immediately in order to maximize the possibility that media can be exchanged as quickly as possible. <note>Concurrent with negotiation of the ICE candidates, it is possible for the initiator and responder to negotiate which content types the session will include, which transport methods will be tried for each content type, etc. Those negotiation flows are shown in other specifications, such as <cite>XEP-0166</cite>. This document specifies only negotiation of the ICE transport method.</note></p>
<p>Note: In order to expedite session establishment, the initiator MAY send transport candidates immediately after sending the "session-initiate" message and before receiving acknowledgement from the receiver (i.e., the initiator MUST consider the session to be live even before receiving acknowledgement). Given in-order delivery, the receiver should receive such "transport-info" messages after receiving the "session-initiate" message; if not, it is appropriate for the receiver to return &lt;unknown-session/&gt; errors since it according to its state machine the session does not exist. If either party receives an &lt;unknown-session/&gt; from the other party, it MUST terminate the negotiation and the session.</p> <p>Note: In order to expedite session establishment, the initiator MAY send transport candidates immediately after sending the "session-initiate" message and before receiving acknowledgement from the responder (i.e., the initiator MUST consider the session to be live even before receiving acknowledgement). Given in-order delivery, the responder should receive such "transport-info" messages after receiving the "session-initiate" message; if not, it is appropriate for the responder to return &lt;unknown-session/&gt; errors since it according to its state machine the session does not exist. If either party receives an &lt;unknown-session/&gt; from the other party, it MUST terminate the negotiation and the session.</p>
<p>The candidate syntax and negotiation flow are described below. (This document shows negotiation for the ice-udp transport method, but the same principles apply to the ice-tcp transport method.)</p> <p>The candidate syntax and negotiation flow are described below. (This document shows negotiation for the ice-udp transport method, but the same principles apply to the ice-tcp transport method.)</p>
<section3 topic='Syntax of Candidate Element' anchor='protocol-negotiate-candidate'> <section3 topic='Syntax of Candidate Element' anchor='protocol-negotiate-candidate'>
<p>The following is an example of the candidate format:</p> <p>The following is an example of the candidate format:</p>
<example caption="Initiator sends a candidate transport"><![CDATA[ <example caption="A candidate transport"><![CDATA[
<iq from='romeo@montague.net/orchard' <candidate component='1'
id='info1' foundation='1'
to='juliet@capulet.com/balcony' generation='0'
type='set'> ip='10.0.1.1'
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns' network='0'
action='transport-info' port='8998'
initiator='romeo@montague.net/orchard' priority='2114978302'
sid='a73sjjvkla37jfea'> protocol='udp'
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'> pwd='asd88fgpdd777uzjYhagZg'
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'> type='host'
<candidate component='1' ufrag='8hhy'/>
foundation='1'
generation='0'
ip='10.0.1.1'
network='0'
port='8998'
priority='2114978302'
protocol='udp'
pwd='asd88fgpdd777uzjYhagZg'
type='host'
ufrag='8hhy'/>
</transport>
</content>
</jingle>
</iq>
]]></example> ]]></example>
<p>The attributes of the &lt;candidate/&gt; element are described in the following table:</p> <p>The attributes of the &lt;candidate/&gt; element are described in the following table:</p>
<table caption='Candidate Attributes'> <table caption='Candidate Attributes'>
@ -266,7 +264,7 @@
<p>The first step in negotiating connectivity is for both parties to immediately begin sending candidate transport methods to the other client. <note>The fact that both parties send candidates means that Jingle requires each party to be a full implementation of ICE, not a "lite" implementation as specified in &icecore;.</note> These candidates SHOULD be gathered by following the procedure specified in Section 4.1.1 of &icecore; and prioritized by following the procedure specified in Section 4.1.2 of &icecore;. 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 both parties to immediately begin sending candidate transport methods to the other client. <note>The fact that both parties send candidates means that Jingle requires each party to be a full implementation of ICE, not a "lite" implementation as specified in &icecore;.</note> These candidates SHOULD be gathered by following the procedure specified in Section 4.1.1 of &icecore; and prioritized by following the procedure specified in Section 4.1.2 of &icecore;. 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). Note: The responder is only indicating receipt of the candidate, not telling the initiator that the candidate will be used.</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). Note: 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>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>At the same time (i.e., immediately after acknowledging receipt of the session-initiate request, not waiting for the initiator to begin or finish sending candidates), the responder also begins sending potential candidates, in order of desirability according to the responder. 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, a client SHOULD follow the procedure specified in Section 7 of &icecore;.</p> <p>As the initiator and responder receive candidates, they probe the various candidate transports for connectivity. In performing these connectivity checks, a client SHOULD follow the procedure specified in Section 7 of &icecore;.</p>
<example caption="Initiator sends a candidate"><![CDATA[ <example caption="Initiator sends a candidate"><![CDATA[
<iq from='romeo@montague.net/orchard' <iq from='romeo@montague.net/orchard'
@ -283,9 +281,9 @@
foundation='1' foundation='1'
generation='0' generation='0'
ip='10.0.1.1' ip='10.0.1.1'
network='0' network='1'
port='8998' port='8998'
priority='2114978302' priority='2114453759'
protocol='udp' protocol='udp'
pwd='asd88fgpdd777uzjYhagZg' pwd='asd88fgpdd777uzjYhagZg'
type='host' type='host'
@ -351,27 +349,39 @@
]]></example> ]]></example>
<p>For each candidate received, the other party MUST acknowledge receipt or return an error:</p> <p>For each candidate received, the other party MUST acknowledge receipt or return an error:</p>
<example caption="Responder acknowledges receipt"><![CDATA[ <example caption="Responder acknowledges receipt"><![CDATA[
<iq from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='info1' type='result'/> <iq from='juliet@capulet.com/balcony'
id='info1'
to='romeo@montague.net/orchard'
type='result'/>
<iq from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='info2' type='result'/> <iq from='juliet@capulet.com/balcony'
id='info2'
to='romeo@montague.net/orchard'
type='result'/>
<iq from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='info3' type='result'/> <iq from='juliet@capulet.com/balcony'
id='info3'
to='romeo@montague.net/orchard'
type='result'/>
]]></example> ]]></example>
</section3> </section3>
</section2> </section2>
<section2 topic='Acceptance of Successful Candidate' anchor='protocol-acceptance'> <section2 topic='Acceptance of Successful Candidate' anchor='protocol-acceptance'>
<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 'content-accept' (or 'session-accept') to the initiator, specifying the candidate that succeeded:</p> <p>If, based on STUN connectivity checks (see &rfc3489; and &rfc3489bis;), 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 'content-accept' (or 'session-accept') to the initiator, specifying the candidate that succeeded:</p>
<example caption="Responder definitively accepts the successful candidate"><![CDATA[ <example caption="Responder definitively accepts the successful candidate"><![CDATA[
<iq from='juliet@capulet.com/balcony' <iq from='juliet@capulet.com/balcony'
id='accept1' id='accept1'
to='romeo@montague.net/orchard' to='romeo@montague.net/orchard'
type='set'> type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns' <jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-accept' action='session-accept'
initiator='romeo@montague.net/orchard' initiator='romeo@montague.net/orchard'
responder='juliet@capulet.com/balcony' responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'> sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'> <content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'> <transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1' <candidate component='1'
foundation='1' foundation='1'
@ -379,7 +389,7 @@
ip='192.0.2.3' ip='192.0.2.3'
network='1' network='1'
port='45664' port='45664'
priority='1107821052' priority='1678246398'
protocol='udp' protocol='udp'
pwd='asd88fgpdd777uzjYhagZg' pwd='asd88fgpdd777uzjYhagZg'
type='srflx' type='srflx'
@ -389,7 +399,7 @@
</jingle> </jingle>
</iq> </iq>
]]></example> ]]></example>
<p>The &JINGLE; element in the content-accept stanza SHOULD possess a 'responder' attribute that explicitly specifies the full JID of the responding entity. If the 'responder' attribute is provided, all future commmunications SHOULD be sent to the JID provided in the 'responder' attribute.</p> <p>The &JINGLE; element in the content-accept or session-accept stanza SHOULD possess a 'responder' attribute that explicitly specifies the full JID of the responding entity. If the 'responder' attribute is provided, all future commmunications SHOULD be sent to the JID provided in the 'responder' attribute.</p>
<p>If the initiator can also send data over that candidate, then it acknowledges the responder's acceptance:</p> <p>If the initiator can also send data over that candidate, then it acknowledges the responder's acceptance:</p>
<example caption="Initiator acknowledges acceptance of successful candidate"><![CDATA[ <example caption="Initiator acknowledges acceptance of successful candidate"><![CDATA[
<iq from='romeo@montague.net/orchard' <iq from='romeo@montague.net/orchard'
@ -411,6 +421,161 @@
]]></example> ]]></example>
<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 6.8 of <cite>XEP-0166</cite>.</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 6.8 of <cite>XEP-0166</cite>.</p>
</section2> </section2>
<section2 topic='Modifying an Existing Candidate' anchor='protocol-modify'>
<p>The creator of a content type MAY modify an existing, in-use candidate at any time during the session, for example to change the IP address or port. This is done by sending a content-modify action with the changed candidate information, where the value of the 'generation' is incremented to specify that the candidate information is a modification to an existing candidate.</p>
<p>An example follows (change to IP address and port).</p>
<example caption="Initiator modifies the in-use candidate"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='modify1'
to='juliet@capulet.com/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-modify'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1'
foundation='1'
generation='1'
ip='192.0.2.4'
network='1'
port='45665'
priority='1678246398'
protocol='udp'
pwd='asd88fgpdd777uzjYhagZg'
type='srflx'
ufrag='8hhy'/>
</transport>
</content>
</jingle>
</iq>
]]></example>
<p>The recipient then acknowledges receipt.</p>
<example caption="Recipient acknowledges content-modify"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='modify1'
to='romeo@montague.net/orchard'
type='result'/>
]]></example>
<p>If the modification is acceptable, the recipient then sends a content-accept action.</p>
<example caption="Responder definitively accepts the modified candidate"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='accept2'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-accept'
initiator='romeo@montague.net/orchard'
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1'
foundation='1'
generation='1'
ip='192.0.2.4'
network='1'
port='45665'
priority='1678246398'
protocol='udp'
pwd='asd88fgpdd777uzjYhagZg'
type='srflx'
ufrag='8hhy'/>
</transport>
</content>
</jingle>
</iq>
]]></example>
<p>The initiator then acknowledges the responder's acceptance:</p>
<example caption="Initiator acknowledges content-accept"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='accept2'
to='juliet@capulet.com/balcony'
type='result'/>
]]></example>
<p>The parties then use the modified candidate in subsequent communications.</p>
</section2>
<section2 topic='Negotiating a New Candidate' anchor='protocol-renegotiate'>
<p>Even after content acceptance or session acceptance, either party MAY continue to send additional candidates to the other party (e.g., because the user agent has become aware of a new media proxy or NIC). As above, such candidates are shared by sending a transport-info action.</p>
<example caption="Initiator sends a fourth candidate"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='info4'
to='juliet@capulet.com/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='transport-info'
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1'
foundation='1'
generation='0'
ip='10.0.1.2'
network='0'
port='9001'
priority='21149780477'
protocol='udp'
pwd='asd88fgpdd777uzjYhagZg'
type='host'
ufrag='8hhy'/>
</transport>
</content>
</jingle>
</iq>
]]></example>
<p>The receiving party MUST acknowledge receipt of the candidate.</p>
<example caption="Recipient acknowledges receipt"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='info4'
to='romeo@montague.net/orchard'
type='result'/>
]]></example>
<p>The receiving party SHOULD check the newly-offered candidate for connectivity, as above. If the candidate is acceptable, the receiving party shall send a content-accept action.</p>
<example caption="Responder definitively accepts the new candidate"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='accept3'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-accept'
initiator='romeo@montague.net/orchard'
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1'
foundation='1'
generation='0'
ip='10.0.1.2'
network='0'
port='9001'
priority='21149780477'
protocol='udp'
pwd='asd88fgpdd777uzjYhagZg'
type='host'
ufrag='8hhy'/>
</transport>
</content>
</jingle>
</iq>
]]></example>
<p>The other party then acknowledges the content-accept.</p>
<example caption="Initiator acknowledges content-accept"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='accept3'
to='juliet@capulet.com/balcony'
type='result'/>
]]></example>
<p>The parties then use the new candidate in subsequent communications.</p>
</section2>
</section1> </section1>
<section1 topic='Determining Support' anchor='support'> <section1 topic='Determining Support' anchor='support'>
@ -456,10 +621,11 @@
</query> </query>
</iq> </iq>
]]></example> ]]></example>
<p>Naturally, support MAY also be determined via the dynamic, presence-based profile of Service Discovery defined in &xep0115;.</p>
</section1> </section1>
<section1 topic='Implementation Notes' anchor='impl'> <section1 topic='Implementation Notes' anchor='impl'>
<p>In order to speed the negotiation process so that media can flow as quickly as possible, the initiatior should gather and priorities candidates in advance or as soon as the principal begins the process of initiating a session.</p> <p>In order to speed the negotiation process so that media can flow as quickly as possible, the initiatior should gather and prioritize candidates in advance or as soon as the principal begins the process of initiating a session.</p>
</section1> </section1>
<section1 topic='Deployment Notes' anchor='deploy'> <section1 topic='Deployment Notes' anchor='deploy'>