Signaling-Java

Signaling

This app shows how to utilize the OpenTok signaling API to send signals (text messages) to other clients connected to the OpenTok session. You can send a signal message to a specific client, or you can send a message to every client connected to the session.

Using signalling

Send a signal to all clients in a session

Signal can be send while client is connected to the Session (after Session.SessionListener.onConnected(session) has been called and before Session.SessionListener.onDisconnected(session) method is called), so you need to set Session.SessionListener:

session = new Session.Builder(this, OpenTokConfig.API_KEY, OpenTokConfig.SESSION_ID).build();
session.setSessionListener(sessionListener);
session.setSignalListener(signalListener);
session.connect(OpenTokConfig.TOKEN);

The sendSignal method (of the Session object_ is used to to send a signal to all clients in a session:

SignalMessage signal = new SignalMessage(mMessageEditTextView.getText().toString());
session.sendSignal(SIGNAL_TYPE, signal.getMessageText());

The SIGNAL_TYPE parameter is a string value that clients can filter on when listening for signals (You'll see later in the onSignalReceived method).

You can set SIGNAL_TYPE to an empty string if you do not need to set a type or define multiple different types of signals.

You can use a [REST API call(https://tokbox.com/developer/guides/signaling/rest/) to send a signal from your server, instead of from a client connected to the session.

Receive signals in a session

To listen for incomming signals set the Session.SignalListener interface of the Session object:

session = new Session.Builder(this, apiKey, sessionId).build();
session.setSessionListener(sessionListener);
session.setSignalListener(this);
session.connect(token);

The onSignalReceived method is called when the signal is received:

private Session.SignalListener signalListener = new Session.SignalListener() {
    @Override
    public void onSignalReceived(Session session, String type, String data, Connection connection) {

        boolean remote = !connection.equals(session.getConnection());
        if (type != null && type.equals(SIGNAL_TYPE)) {
            showMessage(data, remote);
        }
    }
};

The SIGNAL_TYPE check is performed before processing the signal.

Further Reading

• Review other sample projects
• Read Read more about OpenTok Android SDK