1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.mina.handler.demux;
21
22 import org.apache.mina.core.session.IoSession;
23
24 /**
25 * A handler interface that {@link DemuxingIoHandler} forwards
26 * <tt>messageReceived</tt> or <tt>messageSent</tt> events to. You have to
27 * register your handler with the type of the message you want to get notified
28 * using {@link DemuxingIoHandler#addReceivedMessageHandler(Class, MessageHandler)}
29 * or {@link DemuxingIoHandler#addSentMessageHandler(Class, MessageHandler)}.
30 *
31 * @param <M> The message type
32 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
33 */
34 public interface MessageHandler<M> {
35 /**
36 * A {@link MessageHandler} that does nothing. This is useful when
37 * you want to ignore a message of a specific type silently.
38 */
39 MessageHandler<Object> NOOP = new MessageHandler<Object>() {
40 /**
41 * {@inheritDoc}
42 */
43 @Override
44 public void handleMessage(IoSession session, Object message) {
45 // Do nothing
46 }
47 };
48
49 /**
50 * Invoked when the specific type of message is received from or sent to
51 * the specified <code>session</code>.
52 *
53 * @param session the associated {@link IoSession}
54 * @param message the message to decode. Its type is set by the implementation
55 * @throws Exception if there is an error during the message processing
56 */
57 void handleMessage(IoSession session, M message) throws Exception;
58 }