001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.messaging.simp.annotation;
018
019import java.lang.annotation.Documented;
020import java.lang.annotation.ElementType;
021import java.lang.annotation.Retention;
022import java.lang.annotation.RetentionPolicy;
023import java.lang.annotation.Target;
024
025import org.springframework.core.annotation.AliasFor;
026
027/**
028 * Indicates the return value of a message-handling method should be sent as a
029 * {@link org.springframework.messaging.Message} to the specified destination(s)
030 * further prepended with <code>"/user/{username}"</code> where the user name
031 * is extracted from the headers of the input message being handled.
032 *
033 * <p>Both {@code @SendTo} and {@code @SendToUser} may be used on the same method
034 * in which case a message is sent to the destinations of both annotations.
035 *
036 * <p>This annotation may be placed class-level in which case it is inherited
037 * by methods of the class. At the same time, method-level {@code @SendTo} or
038 * {@code @SendToUser} annotations override any such at the class level.
039
040 * @author Rossen Stoyanchev
041 * @author Sam Brannen
042 * @since 4.0
043 * @see org.springframework.messaging.simp.annotation.support.SendToMethodReturnValueHandler
044 * @see org.springframework.messaging.simp.user.UserDestinationMessageHandler
045 * @see org.springframework.messaging.simp.SimpMessageHeaderAccessor#getUser()
046 */
047@Target({ElementType.TYPE, ElementType.METHOD})
048@Retention(RetentionPolicy.RUNTIME)
049@Documented
050public @interface SendToUser {
051
052        /**
053         * Alias for {@link #destinations}.
054         * @see #destinations
055         */
056        @AliasFor("destinations")
057        String[] value() default {};
058
059        /**
060         * One or more destinations to send a message to.
061         * <p>If left unspecified, a default destination is selected based on the
062         * destination of the input message being handled.
063         * @since 4.2
064         * @see #value
065         * @see org.springframework.messaging.simp.annotation.support.SendToMethodReturnValueHandler
066         */
067        @AliasFor("value")
068        String[] destinations() default {};
069
070        /**
071         * Whether messages should be sent to all sessions associated with the user
072         * or only to the session of the input message being handled.
073         * <p>By default, this is set to {@code true} in which case messages are
074         * broadcast to all sessions.
075         */
076        boolean broadcast() default true;
077
078}