001/*
002 * Copyright 2002-2019 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.web.socket.sockjs.transport.handler;
018
019import java.util.Map;
020
021import org.springframework.http.MediaType;
022import org.springframework.http.server.ServerHttpRequest;
023import org.springframework.web.socket.WebSocketHandler;
024import org.springframework.web.socket.sockjs.frame.DefaultSockJsFrameFormat;
025import org.springframework.web.socket.sockjs.frame.SockJsFrameFormat;
026import org.springframework.web.socket.sockjs.transport.SockJsServiceConfig;
027import org.springframework.web.socket.sockjs.transport.SockJsSession;
028import org.springframework.web.socket.sockjs.transport.TransportType;
029import org.springframework.web.socket.sockjs.transport.session.StreamingSockJsSession;
030
031/**
032 * A TransportHandler for sending messages via Server-Sent Events:
033 * <a href="https://dev.w3.org/html5/eventsource/">https://dev.w3.org/html5/eventsource/</a>.
034 *
035 * @author Rossen Stoyanchev
036 * @since 4.0
037 */
038public class EventSourceTransportHandler extends AbstractHttpSendingTransportHandler {
039
040        @Override
041        public TransportType getTransportType() {
042                return TransportType.EVENT_SOURCE;
043        }
044
045        @Override
046        protected MediaType getContentType() {
047                return new MediaType("text", "event-stream", UTF8_CHARSET);
048        }
049
050        @Override
051        public boolean checkSessionType(SockJsSession session) {
052                return (session instanceof EventSourceStreamingSockJsSession);
053        }
054
055        @Override
056        public StreamingSockJsSession createSession(
057                        String sessionId, WebSocketHandler handler, Map<String, Object> attributes) {
058
059                return new EventSourceStreamingSockJsSession(sessionId, getServiceConfig(), handler, attributes);
060        }
061
062        @Override
063        protected SockJsFrameFormat getFrameFormat(ServerHttpRequest request) {
064                return new DefaultSockJsFrameFormat("data: %s\r\n\r\n");
065        }
066
067
068        private static class EventSourceStreamingSockJsSession extends StreamingSockJsSession {
069
070                public EventSourceStreamingSockJsSession(String sessionId, SockJsServiceConfig config,
071                                WebSocketHandler wsHandler, Map<String, Object> attributes) {
072
073                        super(sessionId, config, wsHandler, attributes);
074                }
075
076                @Override
077                protected byte[] getPrelude(ServerHttpRequest request) {
078                        return new byte[] {'\r', '\n'};
079                }
080        }
081
082}