1 /*
2 * Copyright 2002-2013 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.messaging;
18
19 /**
20 * A {@link MessageChannel} that maintains a registry of subscribers and invokes
21 * them to handle messages sent through this channel.
22 *
23 * @author Mark Fisher
24 * @since 4.0
25 */
26 public interface SubscribableChannel extends MessageChannel {
27
28 /**
29 * Register a message handler.
30 * @return {@code true} if the handler was subscribed or {@code false} if it
31 * was already subscribed.
32 */
33 boolean subscribe(MessageHandler handler);
34
35 /**
36 * Un-register a message handler.
37 * @return {@code true} if the handler was un-registered, or {@code false}
38 * if was not registered.
39 */
40 boolean unsubscribe(MessageHandler handler);
41
42 }