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git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@2797 4b5297f7-1745-476d-ba37-a9c6900126ab
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Peter Saint-Andre 2009-02-26 22:09:17 +00:00
parent c371ff767c
commit 57904ae359
1 changed files with 12 additions and 12 deletions
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xep-0176.xml
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@ -75,13 +75,13 @@
<version>0.19</version>
<date>2008-06-04</date>
<initials>psa</initials>
<remark><p>Allowed batching of multiple candidates in a single transport-info action for optional interworking with the SDP offer-answer model, and added urn:ietf:rfc:3264 service discovery feature to advertise such support; updated security considerations regarding sharing of IP addresses.</p></remark>
<remark><p>Allowed batching of multiple candidates in a single transport-info message for optional interworking with the SDP offer-answer model, and added urn:ietf:rfc:3264 service discovery feature to advertise such support; updated security considerations regarding sharing of IP addresses.</p></remark>
</revision>
<revision>
<version>0.18</version>
<date>2008-05-28</date>
<initials>psa</initials>
<remark><p>Removed content-replace action from acceptance flow, since in ICE that information is sent via STUN, not in the signalling channel.</p></remark>
<remark><p>Removed content-replace message from acceptance flow, since in ICE that information is sent via STUN, not in the signalling channel.</p></remark>
</revision>
<revision>
<version>0.17</version>
@ -451,8 +451,8 @@ INITIATOR RESPONDER
<section2 topic='Candidate Negotiation' anchor='protocol-candidates'>
<p>The initiator and responder negotiate connectivity over ICE by exchanging XML-formatted transport candidates for the channel. This negotiation proceeds immediately in order to maximize the possibility that connectivity can be established (and therefore media can be exchanged) as quickly as possible. In order to expedite session establishment, the initiator SHOULD include transport candidates in its session-initiate message but MAY also send additional transport candidates as soon as it learns of them, even before receiving acknowledgement of the session-initiate message (i.e., the initiator MUST consider the session to be live as soon as it sends the session-initiate message). <note>Given in-order delivery as mandated by &xmppcore;, the responder will 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 according to its state machine the session does not exist.</note></p>
<p>The first step in negotiating connectivity is for each party to send transport candidates to the other party. <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; (typically by communicating with a standalone STUN server in order to discover the client's public IP address and port) and prioritized by following the procedure specified in Section 4.1.2 of &icecore;.</p>
<p>Each candidate or set of candidates shall be sent as &lt;candidate/&gt; children of a &TRANSPORT; element qualified by the 'urn:xmpp:jingle:transports:ice-udp:1' namespace. The &TRANSPORT; element is sent via a Jingle action of session-initiate, session-accept, or transport-info.</p>
<p>Either party MAY include multiple &lt;candidate/&gt; elements in one &TRANSPORT; element, especially in the session-initiate and session-accept messages sent at the beginning of the session negotiation. Including multiple candidates in the session-initiate and session-accept messages can help to ensure interoperability with entities that implement the SDP offer/answer model described in <cite>RFC 3264</cite>; in particular, an entity SHOULD include multiple candidates in its session-initiate or session-accept message if the other party advertises support for the "urn:ietf:rfc:3264" service discovery feature as described in the <link url='#support-sdp'>SDP Offer / Answer Support</link> section of this document. However, including one candidate per subsequent transport-info action typically results in a faster negotiation because the candidates most likely to succeed are sent first (in the session-info and session-accept messages) and it is not necessary to gather all candidates before beginning to send any candidates; furthermore, because certain candidates can be more "expensive" in terms of bandwidth or processing power, either party might not want to advertise the existence of such candidates unless it is necessary to do so after other candidates have failed.</p>
<p>Each candidate or set of candidates shall be sent as &lt;candidate/&gt; children of a &TRANSPORT; element qualified by the 'urn:xmpp:jingle:transports:ice-udp:1' namespace. The &TRANSPORT; element is sent via a Jingle message of type session-initiate, session-accept, or transport-info.</p>
<p>Either party MAY include multiple &lt;candidate/&gt; elements in one &TRANSPORT; element, especially in the session-initiate and session-accept messages sent at the beginning of the session negotiation. Including multiple candidates in the session-initiate and session-accept messages can help to ensure interoperability with entities that implement the SDP offer/answer model described in <cite>RFC 3264</cite>; in particular, an entity SHOULD include multiple candidates in its session-initiate or session-accept message if the other party advertises support for the "urn:ietf:rfc:3264" service discovery feature as described in the <link url='#support-sdp'>SDP Offer / Answer Support</link> section of this document. However, including one candidate per subsequent transport-info message typically results in a faster negotiation because the candidates most likely to succeed are sent first (in the session-info and session-accept messages) and it is not necessary to gather all candidates before beginning to send any candidates; furthermore, because certain candidates can be more "expensive" in terms of bandwidth or processing power, either party might not want to advertise the existence of such candidates unless it is necessary to do so after other candidates have failed.</p>
<p>If the party that receives a candidate in a Jingle message can successfully process a given candidate or set of candidates, it returns an IQ-result (if not, for example because the candidate data is improperly formatted, it returns an IQ-error). At this point, the receiving entity is only indicating receipt of the candidate or set of candidates, not telling the other party that the candidate will be used.</p>
<p>The initiator can keep sending candidates (without stopping to receive an acknowledgement of receipt from the responder for each candidate) until it has exhausted its supply of possible or desirable transport candidates; for each candidate or set of candidates, the responder acknowledges receipt. The responder can also keep sending potential candidates, which the initiator will acknowledge.</p>
</section2>
@ -556,7 +556,7 @@ INITIATOR NAT RESPONDER
<p>In the unlikely event that one of the parties determines that it cannot establish connectivity even after sending and checking lower-priority candidates, it SHOULD terminate the session as described in <cite>XEP-0166</cite>.</p>
</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 transport-replace action with the changed candidate information, where the value of the 'generation' attribute is incremented to specify that the candidate information is a modification to an existing candidate.</p>
<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 transport-replace message with the changed candidate information, where the value of the 'generation' attribute 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.lit/orchard'
@ -593,7 +593,7 @@ INITIATOR NAT RESPONDER
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>If the transport-replace is acceptable, the recipient then sends a transport-accept action (if not, the recipient sends a transport-reject action).</p>
<p>If the transport-replace is acceptable, the recipient then sends a transport-accept message (if not, the recipient sends a transport-reject message).</p>
<example caption="Responder definitively accepts the replaced candidate"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept2'
@ -633,7 +633,7 @@ INITIATOR NAT RESPONDER
<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 media has begun to flow, 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 network interface card). As above, such candidates are shared by sending a transport-info action.</p>
<p>Even after media has begun to flow, 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 network interface card). As above, such candidates are shared by sending a transport-info message.</p>
<example caption="Initiator sends a subsequent candidate"><![CDATA[
<iq from='romeo@montague.lit/orchard'
id='info4'
@ -669,7 +669,7 @@ INITIATOR NAT RESPONDER
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>The parties SHOULD check the newly-offered candidate for connectivity, as described previously. If the parties determine that media can flow over the candidate, the initiating party MAY send a transport-replace action to the responder in order to use the new candidate.</p>
<p>The parties SHOULD check the newly-offered candidate for connectivity, as described previously. If the parties determine that media can flow over the candidate, the initiating party MAY send a transport-replace message to the responder in order to use the new candidate.</p>
<example caption="Initiator sends transport-replace"><![CDATA[
<iq from='romeo@montague.lit/orchard'
id='rep3'
@ -824,7 +824,7 @@ Romeo Gateway Juliet
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>Immediately the gateway sends a transport-replace action to Romeo, specifying a transport of Raw UDP with a candidate whose IP address and port identify a media relay at the gateway.</p>
<p>Immediately the gateway sends a transport-replace message to Romeo, specifying a transport of Raw UDP with a candidate whose IP address and port identify a media relay at the gateway.</p>
<example caption="Gateway sends transport-replace on behalf of responder"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='replace1'
@ -845,7 +845,7 @@ Romeo Gateway Juliet
</jingle>
</iq>
]]></example>
<p>Romeo then acknowledges the transport-replace action and immediately also sends a transport-accept.</p>
<p>Romeo then acknowledges the transport-replace message and immediately also sends a transport-accept.</p>
<example caption="Initiator acknowledges transport-replace"><![CDATA[
<iq from='romeo@montague.lit/orchard'
id='replace1'
@ -956,7 +956,7 @@ Romeo Gateway Juliet
<p>In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in &xep0115;. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.</p>
</section2>
<section2 topic='SDP Offer / Answer Support' anchor='support-sdp'>
<p>If an entity supports the SDP offer / answer model described in <cite>RFC 3264</cite> and therefore prefers to receive multiple candidates in a single "transport-info" action, it MUST advertise support for the "urn:ietf:rfc:3264" service discovery feature. Typically this feature will be advertised only by gateways between Jingle and SIP.</p>
<p>If an entity supports the SDP offer / answer model described in <cite>RFC 3264</cite> and therefore prefers to receive multiple candidates in a single transport-info message, it MUST advertise support for the "urn:ietf:rfc:3264" service discovery feature. Typically this feature will be advertised only by gateways between Jingle and SIP.</p>
<example caption="Service discovery information request"><![CDATA[
<iq from='romeo@montague.lit/orchard'
id='disco2'
@ -1019,7 +1019,7 @@ Romeo Gateway Juliet
&NSVER;
</section2>
<section2 topic='Service Discovery Features' anchor='registrar-features'>
<p>If an entity supports the SDP offer / answer model described in <cite>RFC 3264</cite> and therefore prefers to receive one "transport-info" action with multiple candidates, it MUST advertise support for the "urn:ietf:rfc:3264" feature.</p>
<p>If an entity supports the SDP offer / answer model described in <cite>RFC 3264</cite> and therefore prefers to receive one transport-info message with multiple candidates, it MUST advertise support for the "urn:ietf:rfc:3264" feature.</p>
<p>The registry submission is as follows.</p>
<code caption='Registry Submission'><![CDATA[
<var>