do we need sessions in WebRTC? - webrtc

Question

I am creating a sample project for learning purpose(later on I will be working on project based on webrtc and kurento), I am using Kurento media server with it, I have modified the tutorial of the kurento server and made one sample out of it.
In all of the samples for Kurento Server they are using a UserRegistry.java where they are storing objects of UserSession as shown below:
public class UserSession {
private static final Logger log = LoggerFactory.getLogger(UserSession.class);
private final String name;
private final WebSocketSession session;
private String sdpOffer;
private String callingTo;
private String callingFrom;
private WebRtcEndpoint webRtcEndpoint;
private WebRtcEndpoint playingWebRtcEndpoint;
private final List<IceCandidate> candidateList = new ArrayList<>();
public UserSession(WebSocketSession session, String name) {
this.session = session;
this.name = name;
}
public void sendMessage(JsonObject message) throws IOException {
log.debug("Sending message from user '{}': {}", name, message);
session.sendMessage(new TextMessage(message.toString()));
}
public String getSessionId() {
return session.getId();
}
public void setWebRtcEndpoint(WebRtcEndpoint webRtcEndpoint) {
this.webRtcEndpoint = webRtcEndpoint;
if (this.webRtcEndpoint != null) {
for (IceCandidate e : candidateList) {
this.webRtcEndpoint.addIceCandidate(e);
}
this.candidateList.clear();
}
}
public void addCandidate(IceCandidate candidate) {
if (this.webRtcEndpoint != null) {
this.webRtcEndpoint.addIceCandidate(candidate);
} else {
candidateList.add(candidate);
}
if (this.playingWebRtcEndpoint != null) {
this.playingWebRtcEndpoint.addIceCandidate(candidate);
}
}
public void clear() {
this.webRtcEndpoint = null;
this.candidateList.clear();
}
}
I have two questions on this:
Why do we need session object?
What are the alternatives(if there are any) to manage session?
Let me give some more background on 2nd question. I found out that I can run the Kurento-JavaScript-Client(I need to convert it to browser version and then I can use it.) on the client side only (That way I won't require a backend server i.e. nodejs or tomcat - this is my assumption). So in this case how would I manage session or I can totally remove the UserRegistry concept and use some other way.
Thanks & Regards

Answer 1

You need to store sessions to implement signalling between the clients and the application server. See for example here. The signalling diagram describes the messages required to start/stop/etc the WebRTC video communication.
If you are planing to get rid of the application server (i.e. move to JavaScript client completely) you can take a look to a publish/subscribe API such as PubNub.