001/*
002 * Copyright 2002-2017 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;
018
019import java.util.Map;
020
021import org.springframework.lang.Nullable;
022import org.springframework.messaging.MessagingException;
023import org.springframework.messaging.core.MessagePostProcessor;
024import org.springframework.messaging.core.MessageSendingOperations;
025
026/**
027 * A specialization of {@link MessageSendingOperations} with methods for use with
028 * the Spring Framework support for Simple Messaging Protocols (like STOMP).
029 *
030 * <p>For more on user destinations see
031 * {@link org.springframework.messaging.simp.user.UserDestinationResolver
032 * UserDestinationResolver}.
033 *
034 * <p>Generally it is expected the user is the one authenticated with the
035 * WebSocket session (or by extension the user authenticated with the
036 * handshake request that started the session). However if the session is
037 * not authenticated, it is also possible to pass the session id (if known)
038 * in place of the user name. Keep in mind though that in that scenario,
039 * you must use one of the overloaded methods that accept headers making sure the
040 * {@link org.springframework.messaging.simp.SimpMessageHeaderAccessor#setSessionId
041 * sessionId} header has been set accordingly.
042 *
043 * @author Rossen Stoyanchev
044 * @since 4.0
045 */
046public interface SimpMessageSendingOperations extends MessageSendingOperations<String> {
047
048        /**
049         * Send a message to the given user.
050         * @param user the user that should receive the message.
051         * @param destination the destination to send the message to.
052         * @param payload the payload to send
053         */
054        void convertAndSendToUser(String user, String destination, Object payload) throws MessagingException;
055
056        /**
057         * Send a message to the given user.
058         * <p>By default headers are interpreted as native headers (e.g. STOMP) and
059         * are saved under a special key in the resulting Spring
060         * {@link org.springframework.messaging.Message Message}. In effect when the
061         * message leaves the application, the provided headers are included with it
062         * and delivered to the destination (e.g. the STOMP client or broker).
063         * <p>If the map already contains the key
064         * {@link org.springframework.messaging.support.NativeMessageHeaderAccessor#NATIVE_HEADERS "nativeHeaders"}
065         * or was prepared with
066         * {@link org.springframework.messaging.simp.SimpMessageHeaderAccessor SimpMessageHeaderAccessor}
067         * then the headers are used directly. A common expected case is providing a
068         * content type (to influence the message conversion) and native headers.
069         * This may be done as follows:
070         * <pre class="code">
071         * SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
072         * accessor.setContentType(MimeTypeUtils.TEXT_PLAIN);
073         * accessor.setNativeHeader("foo", "bar");
074         * accessor.setLeaveMutable(true);
075         * MessageHeaders headers = accessor.getMessageHeaders();
076         * messagingTemplate.convertAndSendToUser(user, destination, payload, headers);
077         * </pre>
078         * <p><strong>Note:</strong> if the {@code MessageHeaders} are mutable as in
079         * the above example, implementations of this interface should take notice and
080         * update the headers in the same instance (rather than copy or re-create it)
081         * and then set it immutable before sending the final message.
082         * @param user the user that should receive the message (must not be {@code null})
083         * @param destination the destination to send the message to (must not be {@code null})
084         * @param payload the payload to send (may be {@code null})
085         * @param headers the message headers (may be {@code null})
086         */
087        void convertAndSendToUser(String user, String destination, Object payload, Map<String, Object> headers)
088                        throws MessagingException;
089
090        /**
091         * Send a message to the given user.
092         * @param user the user that should receive the message (must not be {@code null})
093         * @param destination the destination to send the message to (must not be {@code null})
094         * @param payload the payload to send (may be {@code null})
095         * @param postProcessor a postProcessor to post-process or modify the created message
096         */
097        void convertAndSendToUser(String user, String destination, Object payload, MessagePostProcessor postProcessor)
098                        throws MessagingException;
099
100        /**
101         * Send a message to the given user.
102         * <p>See {@link #convertAndSend(Object, Object, java.util.Map)} for important
103         * notes regarding the input headers.
104         * @param user the user that should receive the message
105         * @param destination the destination to send the message to
106         * @param payload the payload to send
107         * @param headers the message headers
108         * @param postProcessor a postProcessor to post-process or modify the created message
109         */
110        void convertAndSendToUser(String user, String destination, Object payload, @Nullable Map<String, Object> headers,
111                        @Nullable MessagePostProcessor postProcessor) throws MessagingException;
112
113}