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package javax.websocket;


/**
 * The Web Socket Endpoint represents an object that can handle a web socket conversations. When
 * deployed as a server endpoint, that is to say, the endpoint is registered to a URL, the server instantiates
 * a new endpoint instance for each client connection. If
 * deployed as a client, the endpoint will be instantiated once per single connection to the server.
 * If the endpoint is a server which will cater to multiple clients, each endpoint instance corresponding to each active client
 * is called by no more than one thread at a time. This means that when implementing/overriding the methods
 * of Endpoint, the developer is guaranteed that there will be at most one thread in each endpoint instance.
 * 

* Here is an example of a simple endpoint that echoes any incoming text message back to the sender. *

* public class EchoServer extends Endpoint { *


*  public void onOpen(Session session, EndpointConfig config) {

*   final RemoteEndpoint remote = session.getBasicRemote();
*   session.addMessageHandler(new MessageHandler.Basic() {
*    public void onMessage(String text) {
*     try {
*      remote.sendString("Got your message (" + text + "). Thanks !");
*     } catch (IOException ioe) {
*      // handle send failure here
*     }
*    }
*   });

* *  }
* } *
* * @author dannycoward */ public abstract class Endpoint { /** * Developers must implement this method to be notified when a new conversation has * just begun. * * @param session the session that has just been activated. * @param config the configuration used to configure this endpoint. */ public abstract void onOpen(Session session, EndpointConfig config); /** * This method is called immediately prior to the session with the remote * peer being closed. It is called whether the session is being closed * because the remote peer initiated a close and sent a close frame, or * whether the local websocket container or this endpoint requests to close * the session. The developer may take this last opportunity to retrieve * session attributes such as the ID, or any application data it holds before * it becomes unavailable after the completion of the method. Developers should * not attempt to send new messages from this call as the underlying * connection will not be able to send them at this stage. * * @param session the session about to be closed. * @param closeReason the reason the session was closed. */ public void onClose(Session session, CloseReason closeReason) { } /** * Developers may implement this method when the web socket session * creates some kind of error that is not modeled in the web socket protocol. This may for example * be a notification that an incoming message is too big to handle, or that the incoming message could not be encoded.

* There are a number of categories of exception that this method is (currently) defined to handle:-
* - connection problems, for example, a socket failure that occurs before * the web socket connection can be formally closed. These are modeled as * {@link SessionException}s
* - runtime errors thrown by developer created message handlers calls.
* - conversion errors encoding incoming messages before any message handler has been called. These * are modeled as {@link DecodeException}s
* * @param session the session in use when the error occurs. * @param thr the throwable representing the problem. */ public void onError(Session session, Throwable thr) { } }




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