| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package com.datatorrent.lib.helper; |
| |
| import java.io.IOException; |
| import java.util.HashMap; |
| |
| import javax.servlet.http.HttpServletRequest; |
| |
| import org.codehaus.jackson.map.ObjectMapper; |
| import org.eclipse.jetty.websocket.WebSocket; |
| import org.eclipse.jetty.websocket.WebSocketServlet; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import com.datatorrent.common.util.JacksonObjectMapperProvider; |
| |
| /** |
| * |
| */ |
| @SuppressWarnings("serial") |
| public class SamplePubSubWebSocketServlet extends WebSocketServlet |
| { |
| private static final Logger LOG = LoggerFactory.getLogger(SamplePubSubWebSocketServlet.class); |
| private ObjectMapper mapper = (new JacksonObjectMapperProvider()).getContext(null); |
| private PubSubWebSocket subscriber; |
| |
| @Override |
| public WebSocket doWebSocketConnect(HttpServletRequest hsr, String string) |
| { |
| return new PubSubWebSocket(); |
| } |
| |
| private class PubSubWebSocket implements WebSocket.OnTextMessage |
| { |
| private Connection connection; |
| |
| @SuppressWarnings("unchecked") |
| @Override |
| public void onMessage(String arg0) |
| { |
| // This parsing code will be handled by API in future in a manner that is transparent to the |
| // user and should not be relied upon |
| try { |
| HashMap<String, Object> map = mapper.readValue(arg0, HashMap.class); |
| String type = (String)map.get("type"); |
| String topic = (String)map.get("topic"); |
| if (type.equals("subscribe")) { |
| if (topic != null) { |
| subscriber = this; |
| } |
| } else if (type.equals("unsubscribe")) { |
| subscriber = null; |
| } else if (type.equals("publish")) { |
| Object data = map.get("data"); |
| if (data != null) { |
| if (subscriber != null) { |
| sendData(subscriber, topic, data); |
| } |
| } |
| } |
| } catch (Exception ex) { |
| LOG.warn("Data read error", ex); |
| } |
| } |
| |
| @Override |
| public void onOpen(Connection cnctn) |
| { |
| this.connection = cnctn; |
| } |
| |
| @Override |
| public void onClose(int i, String string) |
| { |
| if (subscriber == this) { |
| subscriber = null; |
| } |
| } |
| |
| } |
| |
| private synchronized void sendData(PubSubWebSocket webSocket, String topic, Object data) |
| { |
| // This composing code will be handled by API in future in a manner that is transparent to the |
| // user and should not be relied upon |
| HashMap<String, Object> map = new HashMap<String, Object>(); |
| map.put("type", "data"); |
| map.put("topic", topic); |
| map.put("data", data); |
| try { |
| webSocket.connection.sendMessage(mapper.writeValueAsString(map)); |
| } catch (IOException ex) { |
| LOG.warn("Connection send error", ex); |
| } |
| } |
| |
| public boolean hasSubscriber() |
| { |
| return subscriber != null; |
| } |
| |
| } |