Java tutorial
/* * Copyright 2002-2013 the original author or authors. * * 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 * * https://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.springframework.messaging; /** * A {@link MessageChannel} that maintains a registry of subscribers and invokes * them to handle messages sent through this channel. * * @author Mark Fisher * @since 4.0 */ public interface SubscribableChannel extends MessageChannel { /** * Register a message handler. * @return {@code true} if the handler was subscribed or {@code false} if it * was already subscribed. */ boolean subscribe(MessageHandler handler); /** * Un-register a message handler. * @return {@code true} if the handler was un-registered, or {@code false} * if was not registered. */ boolean unsubscribe(MessageHandler handler); }