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<!DOCTYPE html>
<html lang="en" dir="ltr" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8">
<title>Object RTC (ORTC) API for WebRTC</title>
<script src="http://www.w3.org/Tools/respec/respec-w3c-common" async class="remove"></script>
<script src="respec-config.js" class="remove"></script>
</head>
<body>
<section id="abstract">
<p>
This document defines a set of ECMAScript APIs in WebIDL to allow media to be sent and received
from another browser or device implementing the appropriate set of real-time protocols. However,
unlike the WebRTC 1.0 API, Object Real-Time Communications (ORTC) does not
utilize Session Description Protocol (SDP) in the API,
nor does it mandate support for the Offer/Answer state machine (though an application
is free to choose SDP and Offer/Answer as an on-the-wire signaling mechanism).
Instead, ORTC uses "sender", "receiver" and "transport" objects, which have
"capabilities" describing what they are capable of doing,
as well as "parameters" which define what they are configured to do.
"Tracks" are encoded by senders and sent over transports, then decoded by receivers while
"data channels" are sent over transports directly.
</p>
</section>
<section id="sotd"></section>
<section id="overview*">
<h2><span class="secno"> </span>Overview</h2>
<p>
Object Real-Time Communications (ORTC) provides a powerful API for the development of WebRTC based applications.
ORTC does not utilize Session Description Protocol (SDP) in the API, nor does it mandate support for the Offer/Answer
state machine (though an application
is free to choose SDP and Offer/Answer as an on-the-wire signaling mechanism).
Instead, ORTC uses "sender", "receiver" and "transport" objects, which have
"capabilities" describing what they are capable of doing,
as well as "parameters" which define what they are configured to do.
"Tracks" are encoded by senders and sent over transports, then decoded by receivers while
"data channels" are sent over transports directly.
</p>
<p>
In a Javascript application utilizing the ORTC API,
the relationship between the application and the objects, as well
as between the objects themselves is shown below.
Horizontal or slanted arrows denote the flow of media or data,
whereas vertical arrows denote interactions via methods and events.
</p>
<figure>
<img alt="The non-normative ORTC Big Picture Diagram" src="images/ortc-bigy-picture.svg" style="width:100%" />
<figcaption>
Non-normative ORTC Big Picture Diagram
</figcaption>
</figure>
<p>
In the figure above, the <code><a>RTCRtpSender</a></code> (<a href="#rtcrtpsender*">Section 5</a>) encodes the
track provided as input, which is transported over a <code><a>RTCDtlsTransport</a></code>
(<a href="#rtcdtlstransport*">Section 4</a>).
An <code><a>RTCDataChannel</a></code> (<a href="#rtcdatachannel*">Section 11</a>) utilizes an
<code><a>RTCSctpTransport</a></code> (<a href="#sctp-transport*">Section 12</a>) which can also be multiplexed
over the <code><a>RTCDtlsTransport</a></code>.
Sending of Dual Tone Multi Frequency (DTMF) tones is supported via the
<code><a>RTCDtmfSender</a></code> (<a href="#rtcdtmfsender*">Section 10</a>).
</p>
<p>
The <code><a>RTCDtlsTransport</a></code> utilizes an <code><a>RTCIceTransport</a></code>
(<a href="#rtcicetransport*">Section 3</a>) to select a communication path to reach the
receiving peer's <code><a>RTCIceTransport</a></code>, which is in turn associated with
an <code><a>RTCDtlsTransport</a></code> which de-multiplexes
media to the <code><a>RTCRtpReceiver</a></code> (<a href="#rtcrtpreceiver*">Section 6</a>) and
data to the <code><a>RTCSctpTransport</a></code> and <code><a>RTCDataChannel</a></code>.
The <code><a>RTCRtpReceiver</a></code> then decodes media, producing a track which is rendered
by an audio or video tag.
</p>
<p>
Several other objects also play a role.
The <code><a>RTCIceGatherer</a></code> (<a href="#rtcicegatherer*">Section 2</a>) gathers local ICE candidates for use by one or
more <code><a>RTCIceTransport</a></code> objects, enabling forking scenarios.
The <code><a>RTCIceTransportController</a></code> (<a href="#rtcicetransportcontroller*">Section 7</a>)
manages freezing/unfreezing (defined in [[!RFC5245]]) and bandwidth estimation.
The <code><a>RTCRtpListener</a></code> (<a href="#rtcrtplistener*">Section 8</a>) detects whether an RTP stream is received that
cannot be delivered to any existing <code><a>RTCRtpReceiver</a></code>, providing an <code>onunhandledrtp</code> event handler that the application can use
to correct the situation.
</p>
<p>
Remaining sections of the specification fill in details relating to RTP capabilities and parameters,
operational statistics, media authentication via Certificates and Identity Providers (IdP) and compatibility with the
WebRTC 1.0 API.
RTP dictionaries are described in <a href="#rtcrtpdictionaries*">Section 9</a>,
the Statistics API is described in <a href="#statistics-api">Section 13</a>,
the Identity API is described in <a href="#identity-api">Section 14</a>,
the Certificate API is described in <a href="#certificate-api">Section 15</a>,
an event summary is provided in <a href="#event-summary">Section 16</a>,
WebRTC 1.0 compatibility issues are discussed in <a href="#webrtc-compat*">Section 17</a>,
and complete examples are provided in <a href="#examples*">Section 18</a>.
</p>
<section>
<h3>Terminology</h3>
<p>
The <code><a href="http://dev.w3.org/html5/spec/webappapis.html#eventhandler">EventHandler</a></code>
interface, representing a callback used for event handlers, and the
<a href="http://dev.w3.org/html5/spec/webappapis.html#errorevent"><code><dfn>ErrorEvent</dfn></code></a>
interface are defined in [[!HTML5]].
</p>
<p>
The concepts <dfn><a href="http://dev.w3.org/html5/spec/webappapis.html#queue-a-task">queue a task</a></dfn>,
<dfn><a href= "http://dev.w3.org/html5/spec/webappapis.html#fire-a-simple-event">fires a simple event</a></dfn>
and <dfn><a href="http://dev.w3.org/html5/spec/webappapis.html#networking-task-source">networking task source</a></dfn>
are defined in [[!HTML5]].
</p>
<p>
The terms <dfn>event</dfn>,
<dfn><a href="http://dev.w2.org/html5/spec/webappapis.html#event-handlers">event handlers</a></dfn>
and <dfn><a href= "http://dev.w3.org/html5/spec/webappapis.html#event-handler-event-type">event handler event types</a></dfn>
are defined in [[!HTML5]].
</p>
<p>
The terms <dfn>MediaStream</dfn>, <dfn>MediaStreamTrack</dfn>, and <dfn>MediaStreamConstraints</dfn> are defined in [[!GETUSERMEDIA]].
</p>
</section>
<section>
<h3>Scope</h3>
<p>
For Scalable Video Coding (SVC), the terms single-session transmission (<dfn>SST</dfn>) and multi-session transmission (<dfn>MST</dfn>)
are defined in [[RFC6190]]. This specification only supports <a>SST</a> but not <a>MST</a>.
The term Single Real-time transport protocol stream Single Transport (<dfn>SRST</dfn>),
defined in [[RFC7656]] Section 3.7, refers to an SVC implementation that transmits all layers within a
single transport, using a single Real-time Transport Protocol (RTP) stream and synchronization source (SSRC).
The term Multiple RTP stream Single Transport (<dfn>MRST</dfn>), also defined in [[RFC7656]] Section 3.7, refers
to an implementation that transmits all layers within a single transport, using multiple RTP streams with
a distinct SSRC for each layer. This specification supports SVC codecs utilizing <a>SRST</a> transport
(such as with H.264/SVC, VP8 and VP9). Also, sending of simulcast is supported. SVC codecs supporting
<a>MRST</a> transport (such as H.264/SVC and HEVC) can also be supported, along with reception of simulcast.
However, these features should be considered experimental, since implementation experience is limited.
</p>
<div class="note">
At the time of publication, there were two ORTC implementations supporting simulcast reception.
Since neither implementation supported [[!RFC6051]], mechanisms needed to be provided to handle
intermingling of received simulcast streams due to reordering. The ORTC Lib
implementation deals with this by utilizing timing heuristics as well as "hidden" receivers
for each received simulcast stream, with each "hidden" receiver producing a "hidden" track.
The "hidden" tracks are then mixed internally to produce a single
<code><a>MediaStreamTrack</a></code> <code>RTCRtpReceiver.track</code>.
</div>
</section>
</section>
<section id="rtcicegatherer*">
<h2>The RTCIceGatherer Object</h2>
<p>
The <dfn><code>RTCIceGatherer</code></dfn> gathers local host, server reflexive and relay candidates, as
well as enabling the retrieval of local Interactive Connectivity Establishment (ICE) parameters which can be exchanged in signaling.
By enabling an endpoint to use a set of local candidates to construct
multiple <code><a>RTCIceTransport</a></code> objects, the <code><a>RTCIceGatherer</a></code>
enables support for scenarios such as parallel forking.
</p>
<section id="rtcicegatherer-overview*">
<h3>Overview</h3>
<p>
An <code><a>RTCIceGatherer</a></code> instance can be associated to multiple <code><a>RTCIceTransport</a></code> objects.
The <code><a>RTCIceGatherer</a></code> does not prune local candidates until at least one <code><a>RTCIceTransport</a></code>
object has become associated and all associated <code><a>RTCIceTransport</a></code> objects are in the <code>completed</code> or
<code>failed</code> state.
</p>
<p>
As noted in [[!RFC5245]] Section 7.1.2.2, an incoming connectivity check contains an <code>ICE-CONTROLLING</code>
or <code>ICE-CONTROLLED</code> attribute, depending on the role of the ICE agent initiating the check.
Since an <code><a>RTCIceGatherer</a></code> object does not have a role, it cannot determine whether
to respond to an incoming connectivity check with a 487 (Role Conflict) error; however, it can validate
that an incoming connectivity check utilizes the correct local username fragment and password,
and if not, can respond with an
401 (Unauthorized) error, as described in [[!RFC5389]] Section 10.1.2.
</p>
<p>
For incoming connectivity checks that pass validation, the <code><a>RTCIceGatherer</a></code>
<em class="rfc2119" title="MUST">MUST</em>
buffer the incoming connectivity checks so as to be able to provide them to associated
<code><a>RTCIceTransport</a></code> objects so that they can respond.
</p>
</section>
<section id="rtcicegatherer-operation*">
<h3>Operation</h3>
<p>
An <code><a>RTCIceGatherer</a></code> instance is constructed from an <code><a>RTCIceGatherOptions</a></code> object.
</p>
<p>
An <code><a>RTCIceGatherer</a></code> object in the <code>closed</code> state can be garbage-collected
when it is no longer referenced.
</p>
</section>
<section id="rtcicegatherer-interface-definition*">
<h3>Interface Definition</h3>
<dl class="idl" title="interface RTCIceGatherer : RTCStatsProvider">
<dt>Constructor(RTCIceGatherOptions options)</dt>
<dd></dd>
<dt>readonly attribute RTCIceComponent component</dt>
<dd>
<p>The component-id of the <code><a>RTCIceGatherer</a></code> object. In <code><a>RTCIceGatherer</a></code>
objects returned by <code>createAssociatedGatherer()</code> the value of <var>component</var> is <code>RTCP</code>.
In all other <code><a>RTCIceGatherer</a></code> objects, the value of <var>component</var> is <code>RTP</code>.
</p>
</dd>
<dt>readonly attribute RTCIceGathererState state</dt>
<dd>
<p>The current state of the ICE gatherer.</p>
</dd>
<dt>void close()</dt>
<dd>
<p>
Prunes all local candidates, and closes the port. Associated <code><a>RTCIceTransport</a></code>
objects transition to the <code>disconnected</code> state
(unless they were in the <code>failed</code> state).
Calling <code>close()</code> when <var>state</var> is <code>closed</code> has no effect.
</p>
</dd>
<dt>void gather(optional RTCIceGatherOptions options)</dt>
<dd>
<p>
Gather ICE candidates. If <var>options</var> is omitted, utilize the value
of <var>options</var> passed in the constructor.
</p>
</dd>
<dt>RTCIceParameters getLocalParameters()</dt>
<dd>
<p>Obtain the ICE parameters of the <code><a>RTCIceGatherer</a></code>.</p>
</dd>
<dt>sequence<RTCIceCandidate> getLocalCandidates()</dt>
<dd>
<p>
Retrieve the sequence of valid local candidates associated with the
<code><a>RTCIceGatherer</a></code>.
This retrieves all unpruned local candidates currently known (except for peer reflexive candidates),
even if an <code><a>onlocalcandidate</a></code>
event hasn't been processed yet. Prior to calling <code>gather()</code> an empty list
will be returned.
</p>
</dd>
<dt>RTCIceGatherer createAssociatedGatherer()</dt>
<dd>
<p>
Create an associated <code><a>RTCIceGatherer</a></code> for RTCP, with the same
<code><a>RTCIceParameters</a></code> and <code><a>RTCIceGatherOptions</a></code>.
If <var>state</var> is <code>closed</code>, throw an <code>InvalidStateError</code> exception.
If an <code><a>RTCIceGatherer</a></code> calls the method more than once,
or if <var>component</var> is <code>RTCP</code>, throw
an <code>InvalidStateError</code> exception.
</p>
</dd>
<dt>attribute EventHandler onstatechange</dt>
<dd>
<p>
This event handler, of event handler event type <code><a>statechange</a></code>,
<em class="rfc2119" title="MUST">MUST</em> be fired
any time the <code><a>RTCIceGathererState</a></code> changes.
<p>
</dd>
<dt>attribute EventHandler onerror</dt>
<dd>
<p>
This event handler, of event handler event type <code><a>icecandidateerror<a></code>,
<em class="rfc2119" title="MUST">MUST</em> be fired if an error occurs in the gathering
of ICE candidates (such as if TURN credentials are invalid).
</p>
</dd>
<dt>attribute EventHandler onlocalcandidate</dt>
<dd>
<p>
This event handler, of event handler event type <code>icecandidate</code>, uses
the <code><a>RTCIceGathererEvent</a></code> interface.
It <em class="rfc2119" title="MUST">MUST</em> be supported by all objects implementing the
<code><a>RTCIceGatherer</a></code> interface.
It receives events when a new local ICE candidate is available. Since ICE candidate gathering begins once
an <code><a>RTCIceGatherer</a></code> object is created,
<code>candidate</code> events are queued until an <code>onlocalcandidate</code> event handler is assigned.
When the final candidate is gathered, a <code>candidate</code> event occurs with an <code>RTCIceCandidateComplete</code> emitted.
</p>
</dd>
</dl>
</section>
<section id="rtciceparameters*">
<h3>The RTCIceParameters Object</h3>
<p>
The <dfn><code>RTCIceParameters</code></dfn> object includes the ICE username fragment
and password and other ICE-related parameters.
</p>
<dl class="idl" title="dictionary RTCIceParameters">
<dt>DOMString usernameFragment</dt>
<dd>
<p>ICE username fragment.</p>
</dd>
<dt>DOMString password</dt>
<dd>
<p>ICE password.</p>
</dd>
<dt>boolean iceLite</dt>
<dd>
<p>
If only ICE-lite is supported (<code>true</code>) or not (<code>false</code> or unset). Since
[[!RTCWEB-TRANSPORT]] Section 3.4 requires browser support for full ICE,
<var>iceLite</var> will only be <code>true</code> for a remote peer such as
a gateway. <code>getLocalParameters().iceLite</code> MUST NOT be set.
</p>
</dd>
</dl>
</section>
<section id="rtcicecandidate*">
<h3>The RTCIceCandidate Object</h3>
<p>
The <dfn><code>RTCIceCandidate</code></dfn> object includes information relating to an ICE candidate.
</p>
<pre class="example highlight">
{
foundation: "abcd1234",
priority: 1694498815,
ip: "192.0.2.33",
protocol: "udp",
port: 10000,
type: "host"
};
</pre>
<dl class="idl" title="typedef (RTCIceCandidate or RTCIceCandidateComplete) RTCIceGatherCandidate">
</dl>
<dl class="idl" title="dictionary RTCIceCandidate">
<dt>DOMString foundation</dt>
<dd>
<p>A unique identifier that allows ICE to correlate candidates that appear on multiple <code><a>RTCIceTransport</a></code>s.</p>
</dd>
<dt>unsigned long priority</dt>
<dd>
<p>The assigned priority of the candidate. This is automatically populated by the browser.</p>
</dd>
<dt>DOMString ip</dt>
<dd>
<p>The IP address of the candidate.</p>
</dd>
<dt>RTCIceProtocol protocol</dt>
<dd>
<p>The protocol of the candidate (UDP/TCP).</p>
</dd>
<dt>unsigned short port</dt>
<dd>
<p>The port for the candidate.</p>
</dd>
<dt>RTCIceCandidateType type</dt>
<dd>
<p>The type of candidate.</p>
</dd>
<dt>RTCIceTcpCandidateType tcpType</dt>
<dd>
<p>The type of TCP candidate.</p>
</dd>
<dt>DOMString relatedAddress=""</dt>
<dd>
<p>
For candidates that are derived from others, such as relay or reflexive candidates, the <dfn><code>relatedAddress</code></dfn>
refers to the candidate that these are derived from. For host candidates, the <var>relatedAddress</var>
is set to the empty string.
</p>
</dd>
<dt>unsigned short relatedPort</dt>
<dd>
<p>
For candidates that are derived from others, such as relay or reflexive candidates, the <dfn><code>relatedPort</code></dfn>
refers to the host candidate that these are derived from. For host candidates, the <var>relatedPort</var>
is 0.
</p>
</dd>
</dl>
<section>
<h4>The RTCIceProtocol</h4>
<p>
The <dfn><code>RTCIceProtocol</code></dfn> includes the protocol of the ICE candidate.
</p>
<dl class="idl" title="enum RTCIceProtocol">
<dt>udp</dt>
<dd>
<p>A UDP candidate, as described in [[!RFC5245]].</p>
</dd>
<dt>tcp</dt>
<dd>
<p>A TCP candidate, as described in [[!RFC6544]].</p>
</dd>
</dl>
</section>
<section>
<h4>The RTCIceTcpCandidateType</h4>
<p>
The <dfn><code>RTCIceTcpCandidateType</code></dfn> includes the type of the ICE TCP candidate, as described in [[!RFC6544]].
Browsers MUST gather active TCP candidates and only active TCP candidates.
Servers and other endpoints MAY gather active, passive or so candidates.
</p>
<dl class="idl" title="enum RTCIceTcpCandidateType">
<dt>active</dt>
<dd>
<p>
An active TCP candidate is one for which the transport will
attempt to open an outbound connection but will not receive incoming
connection requests.
</p>
</dd>
<dt>passive</dt>
<dd>
<p>
A passive TCP candidate is one for which the transport
will receive incoming connection attempts but not attempt a
connection.
</p>
</dd>
<dt>so</dt>
<dd>
<p>
An so candidate is one for which the transport will attempt
to open a connection simultaneously with its peer.
</p>
</dd>
</dl>
</section>
<section>
<h4>The RTCIceCandidateType</h4>
<p>
The <dfn><code>RTCIceCandidateType</code></dfn> includes the type of the ICE candidate as defined in [[!RFC5245]] section 15.1.
</p>
<dl class="idl" title="enum RTCIceCandidateType">
<dt>host</dt>
<dd>
<p>A host candidate, as defined in Section 4.1.1.1 of [[!RFC5245]].</p>
</dd>
<dt>srflx</dt>
<dd>
<p>A server reflexive candidate, as defined in Section 4.1.1.2 of [[!RFC5245]].</p>
</dd>
<dt>prflx</dt>
<dd>
<p>A peer reflexive candidate, as defined in Section 4.1.1.2 of [[!RFC5245]].</p>
</dd>
<dt>relay</dt>
<dd>
<p>A relay candidate, as defined in Section 7.1.3.2.1 of [[!RFC5245]].</p>
</dd>
</dl>
</section>
</section>
<section id="rtcicecandidatecomplete*">
<h3>dictionary RTCIceCandidateComplete</h3>
<p>
<dfn><code>RTCIceCandidateComplete</code></dfn> is a dictionary signifying that all <code>RTCIceCandidate</code>s are gathered.
<p>
<dl class="idl" title="dictionary RTCIceCandidateComplete">
<dt>boolean complete=true</dt>
<dd>
<p>This attribute is always present and set to <code>true</code>, indicating that ICE candidate gathering is complete.</p>
</dd>
</dl>
</section>
<section id="rtcicegathererstate*">
<h3>enum RTCIceGathererState</h3>
<p><dfn><code>RTCIceGathererState</code></dfn> represents the current state of the ICE gatherer.</p>
<dl class="idl" title="enum RTCIceGathererState">
<dt>new</dt>
<dd>
<p>
The object has been created but <code>gather()</code> has not been called.
</p>
</dd>
<dt>gathering</dt>
<dd>
<p>
<code>gather()</code> has been called, and the <code><a>RTCIceGatherer</a></code> is
in the process of gathering candidates (which includes adding new candidates and
removing invalidated candidates).
</p>
</dd>
<dt>complete</dt>
<dd>
<p>
The <code><a>RTCIceGatherer</a></code> has completed gathering. Events such as adding, updating or removing an interface,
or adding, changing or removing a TURN server will cause the state to go back to <code>gathering</code> before re-entering
<code>complete</code> once all candidate changes are finalized.
</p>
</dd>
<dt>closed</dt>
<dd>
<p>The <code><a>RTCIceGatherer</a></code> has been closed intentionally (by calling <code>close()</code>).</p>
</dd>
</dl>
</section>
<section>
<h4>RTCIceGathererIceErrorEvent</h4>
<p>
The <code><a>icecandidateerror</a></code> event of the <code><a>RTCIceGatherer</a></code> object uses
the <code><a>RTCIceGathererIceErrorEvent</a></code> interface.
</p>
<dl class="idl" data-merge="RTCIceGathererIceErrorEventInit"
title="interface RTCIceGathererIceErrorEvent : Event">
<dt>Constructor(DOMString type, RTCIceGathererIceErrorEventInit eventInitDict)</dt>
<dd></dd>
<dt>readonly attribute RTCIceCandidate? hostCandidate</dt>
<dd>
<p>
The <code><a>RTCIceCandidate</a></code> used to communicate with the
STUN or TURN server. On a multihomed system, multiple interfaces may be
used to contact the server, and this attribute allows the application to
figure out on which one the failure occurred. If the browser is in a
privacy mode disallowing host candidates, this attribute will be null.
</p>
<p>
If use of multiple interfaces has been prohibited for privacy reasons,
<var>hostCandidate</var> will be null.
</p>
</dd>
<dt>readonly attribute DOMString url</dt>
<dd>
<p>
The <code>url</code> attribute is the STUN or TURN URL identifying
the server on which the failure ocurred.
</p>
</dd>
<dt>readonly attribute unsigned short errorCode</dt>
<dd>
<p>
The <code>errorCode</code> attribute is the numeric STUN
error code returned by the STUN or TURN server [[STUN-PARAMETERS]].
</p>
<p>
If no host candidate can reach the server, <code>errorCode</code>
will be set to a value of 701, as this does not conflict
with the STUN error code range, and <var>hostCandidate</var> will be null.
This error is only fired once per server URL while in the
<code>RTCIceGathererState</code> of <code>gathering</code>.
</p>
</dd>
<dt>readonly attribute USVString errorText</dt>
<dd>
<p>
The <code>errorText</code> attribute is the STUN reason text
returned by the STUN or TURN server [[STUN-PARAMETERS]].
</p>
<p>
If the server could not be reached, <code>errorText</code> will be set
to an implementation-specific value providing details about the error.
</p>
</dd>
</dl>
<dl class="idl" title="dictionary RTCIceGathererIceErrorEventInit : EventInit">
<dt>RTCIceCandidate hostCandidate</dt>
<dd>
<p>
The <code><a>RTCIceCandidate</a></code> used to communicate with the
STUN or TURN server.
</p>
</dd>
<dt>DOMString url</dt>
<dd>
<p>
The <code>url</code> attribute is the STUN or TURN URL identifying
the server on which the failure ocurred.
</p>
</dd>
<dt>unsigned short errorCode</dt>
<dd>
<p>
The <code>errorCode</code> attribute is the numeric STUN
error code returned by the STUN or TURN server [[STUN-PARAMETERS]].
</p>
</dd>
<dt>USVString errorText</dt>
<dd>
<p>
The <code>errorText</code> attribute is the STUN reason text
returned by the STUN or TURN server [[STUN-PARAMETERS]].
</p>
</dd>
</dl>
</section>
<section>
<h4>RTCIceGathererEvent</h4>
<p>
The <code>icecandidate</code> event of the <code><a>RTCIceGatherer</a></code> object uses
the <code><a>RTCIceGathererEvent</a></code> interface.
</p>
<p>
Firing an
<code><a>RTCIceGathererEvent</a></code> event named
<var>e</var> with an <code><a>RTCIceCandidate</a></code>
<var>candidate</var> and URL <var>url</var> means that an event with the name <var>e</var>,
which does not bubble (except where otherwise stated) and is not
cancelable (except where otherwise stated), and which uses the
<code><a>RTCIceGathererEvent</a></code> interface with the
<code>candidate</code> attribute set to the new ICE candidate,
<em class="rfc2119" title="MUST">MUST</em> be
created and dispatched at the given target.
</p>
<dl class="idl" data-merge="RTCIceGathererEventInit"
title="interface RTCIceGathererEvent : Event">
<dt>Constructor(DOMString type, RTCIceGathererEventInit eventInitDict)</dt>
<dd></dd>
<dt>readonly attribute RTCIceGatherCandidate candidate</dt>
<dd>
<p>
The <code>candidate</code> attribute is the
<code><a>RTCIceGatherCandidate</a></code> object with the new ICE
candidate that caused the event.
If <code>candidate</code> is of type <code>RTCIceCandidateComplete</code>,
there are no additional candidates.
</p>
</dd>
<dt>readonly attribute DOMString url</dt>
<dd>The URL of the server from which the candidate was obtained.</dd>
</dl>
<dl class="idl" title="dictionary RTCIceGathererEventInit : EventInit">
<dt>RTCIceGatherCandidate candidate</dt>
<dd>
<p>The ICE candidate that caused the event.</p>
</dd>
<dt>DOMString url</dt>
<dd>The URL of the server from which the candidate was obtained.</dd>
</dl>
</section>
<section id="rtcicegatheroptions*">
<h3>dictionary RTCIceGatherOptions</h3>
<p><dfn><code>RTCIceGatherOptions</code></dfn> provides options relating to the gathering of ICE candidates.</p>
<dl class="idl" title="dictionary RTCIceGatherOptions">
<dt>RTCIceGatherPolicy gatherPolicy</dt>
<dd>
<p>The ICE gather policy.</p>
</dd>
<dt>sequence<RTCIceServer> iceServers</dt>
<dd>
<p>Additional ICE servers to be configured. Since implementations MAY provide default ICE servers,
and applications can desire to restrict communications to the local LAN, <var>iceServers</var> need not
be set.
</p>
</dd>
</dl>
</section>
<section id="rtcicegatherpolicy*">
<h3>enum RTCIceGatherPolicy</h3>
<p><dfn><code>RTCIceGatherPolicy</code></dfn> denotes the policy relating to the gathering of ICE candidates.</p>
<dl class="idl" title="enum RTCIceGatherPolicy">
<dt>all</dt>
<dd>
<p>
The <code><a>RTCIceGatherer</a></code> gathers all types of candidates
when this value is specified. This will not include addresses that have been
filtered by the browser.
</p>
</dd>
<dt>nohost</dt>
<dd>
<p>
The <code><a>RTCIceGatherer</a></code> gathers all ICE candidate types
except for host candidates.
</p>
</dd>
<dt>relay</dt>
<dd>
<p>
The <code><a>RTCIceGatherer</a></code> <em class="rfc2119" title="MUST">MUST</em>
only gather media relay candidates such as candidates passing through a TURN server.
This can be used to reduce leakage of IP addresses in certain use cases.
</p>
</dd>
</dl>
</section>
<section id="rtcicecredentialtype*">
<h3>enum RTCIceCredentialType</h3>
<p><dfn><code>RTCIceCredentialType</code></dfn> represents the type of credential used by a TURN server.</p>
<dl class="idl" title="enum RTCIceCredentialType">
<dt>password</dt>
<dd>
<p>The credential is a long-term authentication password, as described in [[!RFC5389]], Section 10.2.</p>
</dd>
<dt>token</dt>
<dd>
<p>The credential is an access token, as described in [[RFC7635]], Section 6.2.</p>
</dd>
</dl>
</section>
<section id="rtciceserver*">
<h3>The RTCIceServer Object</h3>
<p>
The <dfn><code>RTCIceServer</code></dfn> is used to provide STUN or TURN server configuration.
In network topologies with multiple layers of NATs, it is desirable to have a STUN server
between every layer of NATs in addition to the TURN servers to minimize the peer to peer network latency.
</p>
<p>
An example of an array of <code><a>RTCIceServer</a></code> objects:
</p>
<pre class="example highlight">
[
{ urls: "stun:stun1.example.net" },
{ urls: "turn:turn.example.org", username: "user", credential: "myPassword",
credentialType: "password"}
]
</pre>
<dl class="idl" title="dictionary RTCIceServer">
<dt>required (DOMString or sequence<DOMString>) urls</dt>
<dd>
<p>STUN or TURN URI(s) as defined in [[!RFC7064]] and [[!RFC7065]] or other URI types.</p>
</dd>
<dt>DOMString username</dt>
<dd>
<p>
If this <code><a>RTCIceServer</a></code> object represents a TURN server, then this attribute specifies
the username to use with that TURN server.
</p>
</dd>
<dt>DOMString credential</dt>
<dd>
<p>If this <code><a>RTCIceServer</a></code> represents a TURN server, then this attribute specifies the credential to use with that TURN server.</p>
</dd>
<dt>RTCIceCredentialType credentialType = "password"</dt>
<dd>
<p>
If this <code><a>RTCIceServer</a></code> object represents a TURN Server, then this
attribute specifies how <var>credential</var> should be used when that TURN server requests authorization.
</p>
</dd>
</dl>
</section>
<section id="rtcicegatherer-initial-example*">
<h3>Example</h3>
<pre class="example highlight">
// Example to demonstrate use of RTCIceCandidateComplete
// Include some helper functions
import {trace, errorHandler, mySendLocalCandidate, myIceGathererStateChange,
myIceTransportStateChange, myDtlsTransportStateChange} from 'helper';
// Create ICE gather options
var gatherOptions = {
gatherPolicy: "relay",
iceServers: [
{ urls: "stun:stun1.example.net" },
{ urls: "turn:turn.example.org", username: "user", credential: "myPassword",
credentialType: "password" }
]
};
// Create IceGatherer object
var iceGatherer = new RTCIceGatherer(gatherOptions);
// Handle state changes
iceGatherer.onstatechange = function(event) {
myIceGathererStateChange("iceGatherer", event.state);
};
// Prepare to signal local candidates
iceGatherer.onlocalcandidate = function(event) {
mySendLocalCandidate(event.candidate);
};
// Start gathering
iceGatherer.gather();
// Set up response function
mySignaller.onResponse = function(responseSignaller, response) {
// We may get N responses
// ... deal with the N responses as shown in Example 5 of Section 3.11.
};
mySignaller.send({
"ice": iceGatherer.getLocalParameters()
});
</pre>
<pre class="example highlight">
// Helper functions used in all the examples (helper.js)
export function trace(text) {
// This function is used for logging.
text = text.trimRight();
if (window.performance) {
var now = (window.performance.now() / 1000).toFixed(3);
console.log(now + ": " + text);
} else {
console.log(text);
}
}
export function errorHandler(error) {
trace("Error encountered: " + error.name);
}
export function mySendLocalCandidate(candidate, component, kind, parameters) {
// Set default values
kind = kind || "all";
component = component || "RTP";
parameters = parameters || null;
// Signal the local candidate
mySignaller.mySendLocalCandidate({
"candidate": candidate,
"component": component,
"kind": kind,
"parameters": parameters
});
}
export function myIceGathererStateChange(name, state) {
switch (state) {
case "new":
trace("IceGatherer: " + name + " Has been created");
break;
case "gathering":
trace("IceGatherer: " + name + " Is gathering candidates");
break;
case "complete":
trace("IceGatherer: " + name + " Has finished gathering (for now)");
break;
case "closed":
trace("IceGatherer: " + name + " Is closed");
break;
default:
trace("IceGatherer: " + name + " Invalid state");
}
}
export function myIceTransportStateChange(name, state) {
switch (state) {
case "new":
trace("IceTransport: " + name + " Has been created");
break;
case "checking":
trace("IceTransport: " + name + " Is checking");
break;
case "connected":
trace("IceTransport: " + name + " Is connected");
break;
case "disconnected":
trace("IceTransport: " + name + " Is disconnected");
break;
case "completed":
trace("IceTransport: " + name + " Has finished checking (for now)");
break;
case "failed":
trace("IceTransport: " + name + " Has failed");
break;
case "closed":
trace("IceTransport: " + name + " Is closed");
break;
default:
trace("IceTransport: " + name + " Invalid state");
}
}
export function myDtlsTransportStateChange(name, state){
switch(state){
case "new":
trace('DtlsTransport: ' + name + ' Has been created');
break;
case "connecting":
trace('DtlsTransport: ' + name + ' Is connecting');
break;
case "connected":
trace('DtlsTransport: ' + name + ' Is connected');
break;
case "failed":
trace('DtlsTransport: ' + name + ' Has failed');
break;
case "closed":
trace('DtlsTransport: ' + name + ' Is closed');
break;
default:
trace('DtlsTransport: ' + name + ' Invalid state');
}
}
</pre>
</section>
</section>
<section id="rtcicetransport*">
<h2>The RTCIceTransport Object</h2>
<p>
The <dfn><code>RTCIceTransport</code></dfn> allows an application access to information about the Interactive
Connectivity Establishment (ICE) transport over which packets are sent and received.
In particular, ICE manages peer-to-peer connections which involve state which the application may want to access.
</p>
<section id="rtcicetransport-overview*">
<h3>Overview</h3>
<p>
An <code><a>RTCIceTransport</a></code> instance is associated to a transport object (such as <code><a>RTCDtlsTransport</a></code>),
and provides RTC related methods to it.
</p>
</section>
<section id="rtcicetransport-operation*">
<h3>Operation</h3>
<p>
An <code><a>RTCIceTransport</a></code> instance is constructed (optionally) from an <code><a>RTCIceGatherer</a></code>.
If <code>gatherer.state</code> is <code>closed</code> or <code>gatherer.component</code> is <code>RTCP</code>, then throw an <code>InvalidStateError</code> exception.
</p>
<p>
An <code><a>RTCIceTransport</a></code> object in the <code>closed</code> state can be garbage-collected
when it is no longer referenced.
</p>
</section>
<section id="rtcicetransport-interface-definition*">
<h3>Interface Definition</h3>
<dl class="idl" title="interface RTCIceTransport : RTCStatsProvider">
<dt>Constructor(optional RTCIceGatherer gatherer)</dt>
<dd></dd>
<dt>readonly attribute RTCIceGatherer? iceGatherer</dt>
<dd>
<p>
The <code>iceGatherer</code> attribute is set to the value of <var>gatherer</var> if passed in the constructor or in the latest call to <code>start()</code>.
</p>
</dd>
<dt>readonly attribute RTCIceRole role</dt>
<dd>
<p>The current role of the ICE transport.</p>
</dd>
<dt>readonly attribute RTCIceComponent component</dt>
<dd>
<p>The component-id of the <code><a>RTCIceTransport</a></code> object. In <code><a>RTCIceTransport</a></code>
objects returned by <code>createAssociatedTransport()</code>, the value of <code>component</code> is
<code>RTCP</code>. In all other <code><a>RTCIceTransport</code></a> objects, the value of <code>component</code> is <code>RTP</code>.
</p>
</dd>
<dt>readonly attribute RTCIceTransportState state</dt>
<dd>
<p>The current state of the ICE transport.</p>
</dd>
<dt>sequence<RTCIceCandidate> getRemoteCandidates()</dt>
<dd>
<p>
Retrieve the sequence of candidates associated with the remote
<code><a>RTCIceTransport</a></code>. Only returns the candidates previously
added using <code>setRemoteCandidates()</code> or <code>addRemoteCandidate()</code>.
If there are no remote candidates, an empty list is returned.
</p>
</dd>
<dt>RTCIceCandidatePair? getSelectedCandidatePair()</dt>
<dd>
<p>
Retrieves the selected candidate pair on which packets are sent. If there is no selected pair yet,
or consent [[!RFC7675]] is lost on the selected pair, NULL is returned.
</p>
</dd>
<dt>void start(RTCIceGatherer gatherer, RTCIceParameters remoteParameters, optional RTCIceRole role)</dt>
<dd>
<p>
The first time <code>start()</code> is called, candidate connectivity checks are started and the
ICE transport attempts to connect to the remote <code><a>RTCIceTransport</a></code>.
If <code>start()</code> is called with invalid parameters, throw an <code>InvalidParameters</code> exception.
For example, if <var>gatherer.component</var> has a value different from <var>iceTransport.component</var>,
throw an <code>InvalidParameters</code> exception. If <var>state</var> or <var>gatherer.state</var> is <code>closed</code>,
throw an <code>InvalidStateError</code> exception. When <code>start()</code> is called again,
<code><a>RTCIceTransportState</a></code> transitions to the <code>connected</code> state, all remote candidates
are flushed, and <code>addRemoteCandidate()</code> or <code>setRemoteCandidates()</code> must be called
to add the remote candidates back or replace them.
</p>
<p>
If a newly constructed <code><a>RTCIceGatherer</a></code> object is passed as an argument when <code>start()</code>
is called again, an ICE restart as defined in [[!RFC5245]] Section 9.2.1.1 occurs.
Since <code>start()</code> does not change the username fragment and password of <var>gatherer</var>,
if <code>start()</code> is called again with the same value of <var>gatherer</var>,
the existing local candidates are reused and the ICE username fragment and password remains unchanged.
However, other aspects of the behavior are not currently defined.
</p>
<p>
As noted in [[!RFC5245]] Section 7.1.2.3, an incoming connectivity check utilizes the local/remote username fragment
and the local password, whereas an outgoing connectivity check utilizes the local/remote username fragment and the
remote password. Since <code>start()</code> provides role information, as well as the remote username fragment and password,
once <code>start()</code> is called an <code><a>RTCIceTransport</a></code> object
can respond to incoming connectivity checks based on its configured role, as well as initiating connectivity checks.
</p>
</dd>
<dt>void stop()</dt>
<dd>
<p>
Stops and closes the current object. Also removes the object from the
<code><a>RTCIceTransportController</a></code>.
Calling <code>stop()</code> when <var>state</var> is <code>closed</code> has no effect.
</p>
</dd>
<dt>RTCIceParameters? getRemoteParameters()</dt>
<dd>
<p>Obtain the current ICE parameters of the remote <code><a>RTCIceTransport</a></code>.</p>
</dd>
<dt>RTCIceTransport createAssociatedTransport ()</dt>
<dd>
<p>
Create an associated <code><a>RTCIceTransport</a></code> for RTCP.
If called more than once for the same component, or if <var>state</var> is <code>closed</code>,
throw an <code>InvalidStateError</code> exception. If called when
<code>component</code> is <code>RTCP</code>,
throw an <code>InvalidStateError</code> exception.
</p>
</dd>
<dt>void addRemoteCandidate(RTCIceGatherCandidate remoteCandidate)</dt>
<dd>
<p>
Add a remote candidate associated with the remote <code><a>RTCIceTransport</a></code>.
If <code>state</code> is <code>closed</code>, throw an <code>InvalidStateError</code> exception.
When the remote <code><a>RTCIceGatherer</a></code> emits its final candidate, <code>addRemoteCandidate()</code> should be called
with an <code>RTCIceCandidateComplete</code> dictionary as an argument, so that the local <code><a>RTCIceTransport</a></code> can
know there are no more remote candidates expected, and can enter the <code>completed</code> state.
</p>
</dd>
<dt>void setRemoteCandidates(sequence<RTCIceCandidate> remoteCandidates)</dt>
<dd>
<p>
Set the sequence of candidates associated with the remote <code><a>RTCIceTransport</a></code>.
If <code>state</code> is <code>closed</code>, throw an <code>InvalidStateError</code> exception.
</p>
</dd>
<dt>attribute EventHandler onstatechange</dt>
<dd>
<p>