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.nio.charset.StandardCharsets;
020import java.util.Map;
021
022import org.springframework.http.MediaType;
023import org.springframework.http.server.ServerHttpRequest;
024import org.springframework.web.socket.WebSocketHandler;
025import org.springframework.web.socket.sockjs.frame.DefaultSockJsFrameFormat;
026import org.springframework.web.socket.sockjs.frame.SockJsFrameFormat;
027import org.springframework.web.socket.sockjs.transport.SockJsServiceConfig;
028import org.springframework.web.socket.sockjs.transport.SockJsSession;
029import org.springframework.web.socket.sockjs.transport.TransportType;
030import org.springframework.web.socket.sockjs.transport.session.StreamingSockJsSession;
031
032/**
033 * A TransportHandler for sending messages via Server-Sent Events:
034 * <a href="https://dev.w3.org/html5/eventsource/">https://dev.w3.org/html5/eventsource/</a>.
035 *
036 * @author Rossen Stoyanchev
037 * @since 4.0
038 */
039public class EventSourceTransportHandler extends AbstractHttpSendingTransportHandler {
040
041        @Override
042        public TransportType getTransportType() {
043                return TransportType.EVENT_SOURCE;
044        }
045
046        @Override
047        protected MediaType getContentType() {
048                return new MediaType("text", "event-stream", StandardCharsets.UTF_8);
049        }
050
051        @Override
052        public boolean checkSessionType(SockJsSession session) {
053                return (session instanceof EventSourceStreamingSockJsSession);
054        }
055
056        @Override
057        public StreamingSockJsSession createSession(
058                        String sessionId, WebSocketHandler handler, Map<String, Object> attributes) {
059
060                return new EventSourceStreamingSockJsSession(sessionId, getServiceConfig(), handler, attributes);
061        }
062
063        @Override
064        protected SockJsFrameFormat getFrameFormat(ServerHttpRequest request) {
065                return new DefaultSockJsFrameFormat("data: %s\r\n\r\n");
066        }
067
068
069        private static class EventSourceStreamingSockJsSession extends StreamingSockJsSession {
070
071                public EventSourceStreamingSockJsSession(String sessionId, SockJsServiceConfig config,
072                                WebSocketHandler wsHandler, Map<String, Object> attributes) {
073
074                        super(sessionId, config, wsHandler, attributes);
075                }
076
077                @Override
078                protected byte[] getPrelude(ServerHttpRequest request) {
079                        return new byte[] {'\r', '\n'};
080                }
081        }
082
083}