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.web.socket.sockjs.transport.session;
018
019import java.io.IOException;
020import java.util.Map;
021
022import org.springframework.http.server.ServerHttpRequest;
023import org.springframework.http.server.ServerHttpResponse;
024import org.springframework.web.socket.WebSocketHandler;
025import org.springframework.web.socket.sockjs.SockJsTransportFailureException;
026import org.springframework.web.socket.sockjs.frame.SockJsFrame;
027import org.springframework.web.socket.sockjs.frame.SockJsMessageCodec;
028import org.springframework.web.socket.sockjs.transport.SockJsServiceConfig;
029
030/**
031 * A SockJS session for use with streaming HTTP transports.
032 *
033 * @author Rossen Stoyanchev
034 * @since 4.0
035 */
036public abstract class StreamingSockJsSession extends AbstractHttpSockJsSession {
037
038        private int byteCount;
039
040
041        public StreamingSockJsSession(String sessionId, SockJsServiceConfig config,
042                        WebSocketHandler wsHandler, Map<String, Object> attributes) {
043
044                super(sessionId, config, wsHandler, attributes);
045        }
046
047
048        /**
049         * Get the prelude to write to the response before any other data.
050         * @since 4.2
051         */
052        protected abstract byte[] getPrelude(ServerHttpRequest request);
053
054
055        @Override
056        protected void handleRequestInternal(ServerHttpRequest request, ServerHttpResponse response,
057                        boolean initialRequest) throws IOException {
058
059                byte[] prelude = getPrelude(request);
060                response.getBody().write(prelude);
061                response.flush();
062
063                if (initialRequest) {
064                        writeFrame(SockJsFrame.openFrame());
065                }
066                flushCache();
067        }
068
069        @Override
070        protected void flushCache() throws SockJsTransportFailureException {
071                while (!getMessageCache().isEmpty()) {
072                        String message = getMessageCache().poll();
073                        SockJsMessageCodec messageCodec = getSockJsServiceConfig().getMessageCodec();
074                        SockJsFrame frame = SockJsFrame.messageFrame(messageCodec, message);
075                        writeFrame(frame);
076
077                        this.byteCount += (frame.getContentBytes().length + 1);
078                        if (logger.isTraceEnabled()) {
079                                logger.trace(this.byteCount + " bytes written so far, " +
080                                                getMessageCache().size() + " more messages not flushed");
081                        }
082                        if (this.byteCount >= getSockJsServiceConfig().getStreamBytesLimit()) {
083                                logger.trace("Streamed bytes limit reached, recycling current request");
084                                resetRequest();
085                                this.byteCount = 0;
086                                break;
087                        }
088                }
089                scheduleHeartbeat();
090        }
091
092}