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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The RTCSessionDescription interface represents the parameters of a session. Each RTCSessionDescription consists of a description type indicating which part of the offer/answer negotiation process it describes and of the SDP descriptor of the session.
The process of negotiating a connection between two peers involves exchanging RTCSessionDescription objects back and forth until the two peers agree upon a configuration for the connection.
Properties
The RTCSessionDescription interface doesn't inherit any properties.
RTCSessionDescription.typeRead only- An enum of type
RTCSdpTypedescribing the session description's type.
RTCSessionDescription.sdpRead only- A
DOMStringcontaining the SDP describing the session.
Constants
RTCSdpType
This enum defines strings that describe the current state of the session description The session description's type will be represented by one of these.
| Value | Description |
|---|---|
answer |
The session description is the definitive choice in the exchange. In other words, this response indicates that agreement has been reached, and is sent to let the other peer know how to configure itself. Negotiations are complete. |
offer |
The session description is the initial proposal in an offer/answer exchange. The session negotiation process begins with an offer being made. |
pranswer |
The session description is a provisional answer; that is, it's a response to a previous offer or provisional answer. |
rollback |
This session description is used to allow one peer to tell the other, in essence, that an impasse has been reached, and to roll back to the previous state and try again. |
Methods
The RTCSessionDescription doesn't inherit any methods.
RTCSessionDescription()- This constructor returns a new
RTCSessionDescription. The parameter is aRTCSessionDescriptionInitdictionary containing the (optional) values for the two properties. Any values not specified in the dictionary will be initialized tonull. RTCSessionDescription.toJSON()- Returns a JSON description of the object. The values of both properties,
typeandsdp, are contained in the generated JSON.
Example
signalingChannel.onmessage = function (evt) {
if (!pc)
start(false);
var message = JSON.parse(evt.data);
if (message.sdp)
pc.setRemoteDescription(new RTCSessionDescription(message.sdp), function () {
// if we received an offer, we need to answer
if (pc.remoteDescription.type == "offer")
pc.createAnswer(localDescCreated, logError);
}, logError);
else
pc.addIceCandidate(new RTCIceCandidate(message.candidate),
function () {}, logError);
};
Specifications
| Specification | Status | Comment |
|---|---|---|
| WebRTC 1.0: Real-time Communication Between Browser The definition of 'RTCSessionDescription' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) -moz | No support | (Yes) | ? |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | ? | ? | ? | No support | ? | ? |