/*******************************************************************************
* Copyright (c) 2016 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*******************************************************************************/
package org.gameontext.sample.protocol;
import java.io.Closeable;
import java.io.IOException;
import java.util.logging.Level;
import javax.inject.Inject;
import javax.websocket.CloseReason;
import javax.websocket.CloseReason.CloseCodes;
import javax.websocket.EncodeException;
import javax.websocket.EndpointConfig;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.RemoteEndpoint.Basic;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
import org.gameontext.sample.Log;
import org.gameontext.sample.RoomImplementation;
import org.eclipse.microprofile.metrics.annotation.Timed;
import org.eclipse.microprofile.metrics.annotation.Metered;
import org.eclipse.microprofile.metrics.annotation.Counted;
/**
* This is the WebSocket endpoint for a room. Java EE WebSockets
* use simple annotations for event driven methods. An instance of this class
* will be created for every connected client.
* https://book.gameontext.org/microservices/WebSocketProtocol.html
*/
@ServerEndpoint(value = "/room", decoders = MessageDecoder.class, encoders = MessageEncoder.class)
public class RoomEndpoint {
@Inject
protected RoomImplementation roomImplementation;
@Timed(name = "websocket_onOpen_timer",
reusable = true,
tags = "label=websocket")
@Counted(name = "websocket_onOpen_count",
monotonic = true,
reusable = true,
tags = "label=websocket")
@Metered(name = "websocket_onOpen_meter",
reusable = true,
tags = "label=websocket")
@OnOpen
public void onOpen(Session session, EndpointConfig ec) {
Log.log(Level.FINE, this, "A new connection has been made to the room.");
// All we have to do in onOpen is send the acknowledgement
sendMessage(session, Message.ACK_MSG);
}
@Timed(name = "websocket_onClose_timer",
reusable = true,
tags = "label=websocket")
@Counted(name = "websocket_onClose_count",
monotonic = true,
reusable = true,
tags = "label=websocket")
@Metered(name = "websocket_onClose_meter",
reusable = true,
tags = "label=websocket")
@OnClose
public void onClose(Session session, CloseReason r) {
Log.log(Level.FINE, this, "A connection to the room has been closed with reason " + r);
}
@Timed(name = "websocket_onError_timer",
reusable = true,
tags = "label=websocket")
@Counted(name = "websocket_onError_count",
monotonic = true,
reusable = true,
tags = "label=websocket")
@Metered(name = "websocket_onError_meter",
reusable = true,
tags = "label=websocket")
@OnError
public void onError(Session session, Throwable t) {
Log.log(Level.FINE, this, "A problem occurred on connection", t);
// TODO: Careful with what might revealed about implementation details!!
// We're opting for making debug easy..
tryToClose(session,
new CloseReason(CloseReason.CloseCodes.UNEXPECTED_CONDITION,
trimReason(t.getClass().getName())));
}
/**
* The hook into the interesting room stuff.
* @param session
* @param message
* @throws IOException
*/
@Timed(name = "websocket_onMessage_timer",
reusable = true,
tags = "label=websocket")
@Counted(name = "websocket_onMessage_count",
monotonic = true,
reusable = true,
tags = "label=websocket")
@Metered(name = "websocket_onMessage_meter",
reusable = true,
tags = "label=websocket")
@OnMessage
public void receiveMessage(Session session, Message message) throws IOException {
roomImplementation.handleMessage(session, message, this);
}
/**
* Simple broadcast: loop over all mentioned sessions to send the message
* <p>
* We are effectively always broadcasting: a player could be connected
* to more than one device, and that could correspond to more than one connected
* session. Allow topic filtering on the receiving side (Mediator and browser)
* to filter out and display messages.
*
* @param session Target session (used to find all related sessions)
* @param message Message to send
* @see #sendRemoteTextMessage(Session, Message)
*/
@Timed(name = "websocket_sendMessage_timer",
reusable = true,
tags = "label=websocket")
@Counted(name = "websocket_sendMessage_count",
monotonic = true,
reusable = true,
tags = "label=websocket")
@Metered(name = "websocket_sendMessage_meter",
reusable = true,
tags = "label=websocket")
public void sendMessage(Session session, Message message) {
for (Session s : session.getOpenSessions()) {
sendMessageToSession(s, message);
}
}
/**
* Try sending the {@link Message} using
* {@link Session#getBasicRemote()}, {@link Basic#sendObject(Object)}.
*
* @param session Session to send the message on
* @param message Message to send
* @return true if send was successful, or false if it failed
*/
private boolean sendMessageToSession(Session session, Message message) {
if (session.isOpen()) {
try {
session.getBasicRemote().sendObject(message);
return true;
} catch (EncodeException e) {
// Something was wrong encoding this message, but the connection
// is likely just fine.
Log.log(Level.FINE, this, "Unexpected condition writing message", e);
} catch (IOException ioe) {
// An IOException, on the other hand, suggests the connection is
// in a bad state.
Log.log(Level.FINE, this, "Unexpected condition writing message", ioe);
tryToClose(session, new CloseReason(CloseCodes.UNEXPECTED_CONDITION, trimReason(ioe.toString())));
}
}
return false;
}
/**
* @param message String to trim
* @return a string no longer than 123 characters (limit of value length for {@code CloseReason})
*/
private String trimReason(String message) {
return message.length() > 123 ? message.substring(0, 123) : message;
}
/**
* Try to close the WebSocket session and give a reason for doing so.
*
* @param s Session to close
* @param reason {@link CloseReason} the WebSocket is closing.
*/
public void tryToClose(Session s, CloseReason reason) {
try {
s.close(reason);
} catch (IOException e) {
tryToClose(s);
}
}
/**
* Try to close a {@code Closeable} (usually once an error has already
* occurred).
*
* @param c Closable to close
*/
public void tryToClose(Closeable c) {
if (c != null) {
try {
c.close();
} catch (IOException e1) {
}
}
}
}
