Client API. The Codename One framework your app is built on: this runs on the device, not in a backend.

public final class PeerConnection

Object
PeerConnection

One end of a call: the media this device sends, what it receives, and the network path between the two.

The sequence is the standard one. The caller adds its tracks, creates an offer, sets it as its local description and sends it; the callee sets it as its remote description, adds its own tracks, creates an answer, sets that locally and sends it back; the caller sets it as remote. Meanwhile both sides send each other every candidate their listener is given. Carrying the descriptions and candidates is the app’s job – over its own server, a WebSocket, anything – and nothing here sends them.

import com.codename1.io.Log;
import com.codename1.webrtc.*;

WebRtc.openUserMedia(true, false, false).ready(media -> {
    PeerConnection pc = WebRtc.createPeerConnection(new PeerConnectionConfig(),
            new PeerConnection.Listener() {
                public void iceCandidate(PeerConnection connection, IceCandidate candidate) {
                    Log.p("send to the other side: " + candidate.getCandidate());
                }

                public void stateChanged(PeerConnection connection, String state) {
                    Log.p("state " + state);
                }

                public void remoteTrack(PeerConnection connection, MediaTrack track) {
                }
            });
    pc.addTrack(media.getAudio());
    pc.createOffer().ready(offer -> pc.setLocalDescription(offer)
            .ready(done -> Log.p("send to the other side: " + offer.getSdp())));
});

Nested types

interface PeerConnection.Listener What a peer connection tells the app as the call proceeds.

Fields

`public static final` `String NEW = "new"`	`getState()` before the two sides found each other.
`public static final` `String CONNECTING = "connecting"`	`getState()` while a path is being tried.
`public static final` `String CONNECTED = "connected"`	`getState()` while media flows.
`public static final` `String DISCONNECTED = "disconnected"`	`getState()` after the path was lost; it may come back by itself.
`public static final` `String FAILED = "failed"`	`getState()` when no path could be found or it was lost for good.
`public static final` `String CLOSED = "closed"`	`getState()` after `close()`.

Methods

`public` `String getState()`
`public void addTrack(MediaTrack track)`	Sends a local track to the other side.
`public` `AsyncResource<SessionDescription> createOffer()`	Describes this side for the caller’s half of the exchange.
`public` `AsyncResource<SessionDescription> createAnswer()`	Describes this side in answer to the remote offer already set.
`public` `AsyncResource<Boolean> setLocalDescription(SessionDescription description)`
`public` `AsyncResource<Boolean> setRemoteDescription(SessionDescription description)`
`public void addIceCandidate(IceCandidate candidate)`	Tries a path the other side found.
`public void restartIce()`	Gathers new paths on the next offer, for a connection whose path was lost – the device changed network, say, and the addresses the two sides agreed on no longer reach it.
`public void close()`	Ends the connection.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone, finalize

Field details

NEW

public static final String NEW = "new"

getState() before the two sides found each other.

CONNECTING

public static final String CONNECTING = "connecting"

getState() while a path is being tried.

CONNECTED

public static final String CONNECTED = "connected"

getState() while media flows.

DISCONNECTED

public static final String DISCONNECTED = "disconnected"

getState() after the path was lost; it may come back by itself. A phone moving from Wi-Fi to mobile data lands here, and the path it had is usually gone for good: see restartIce().

FAILED

public static final String FAILED = "failed"

getState() when no path could be found or it was lost for good.

CLOSED

public static final String CLOSED = "closed"

getState() after close().

Method details

getState

public String getState()

addTrack

public void addTrack(MediaTrack track)

Sends a local track to the other side. Add every track before creating the offer or the answer.

createOffer

public AsyncResource<SessionDescription> createOffer()

Describes this side for the caller’s half of the exchange.

createAnswer

public AsyncResource<SessionDescription> createAnswer()

Describes this side in answer to the remote offer already set.

setLocalDescription

public AsyncResource<Boolean> setLocalDescription(SessionDescription description)

setRemoteDescription

public AsyncResource<Boolean> setRemoteDescription(SessionDescription description)

addIceCandidate

public void addIceCandidate(IceCandidate candidate)

Tries a path the other side found. A candidate that arrives before the remote description is set is held by the port until it is.

restartIce

public void restartIce()

Gathers new paths on the next offer, for a connection whose path was lost – the device changed network, say, and the addresses the two sides agreed on no longer reach it.

Nothing changes until the offer is exchanged: call this, then createOffer(), and send the offer over the app’s signalling as at the start of the call. The other side answers it with setRemoteDescription(SessionDescription) and createAnswer() and sends that back; tracks, views and the call keep going, and the connection reports CONNECTED again once a new path is found.

Only one side restarts – by convention the one that made the first offer – or both offer at once and neither offer can be answered. DISCONNECTED is the cue to show “reconnecting”, and to restart if it does not recover within a second or two; FAILED is the cue to restart at once.

close

public void close()

Ends the connection. Local tracks stay open: release them separately.