javax.websocket.Endpoint Maven / Gradle / Ivy
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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) {
}
}