com.datatorrent.lib.io.WebSocketInputOperator.java Source code

Java tutorial

Introduction

Here is the source code for com.datatorrent.lib.io.WebSocketInputOperator.java

Source

/**
 * 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.io;

import java.io.IOException;
import java.net.URI;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;

import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.map.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.apex.shaded.ning19.com.ning.http.client.AsyncHttpClient;
import org.apache.apex.shaded.ning19.com.ning.http.client.AsyncHttpClientConfigBean;
import org.apache.apex.shaded.ning19.com.ning.http.client.ws.WebSocket;
import org.apache.apex.shaded.ning19.com.ning.http.client.ws.WebSocketTextListener;
import org.apache.apex.shaded.ning19.com.ning.http.client.ws.WebSocketUpgradeHandler;
import org.apache.commons.lang3.ClassUtils;

import com.datatorrent.api.Context.OperatorContext;

/**
 * Reads via WebSocket from given URL as input stream. 
 * Incoming data is interpreted as JSONObject and converted to {@link java.util.Map}.
 * <p></p>
 * @displayName JSON Map Input
 * @category Input
 * @tags http, websocket
 *
 * @since 0.3.2
 */
public class WebSocketInputOperator<T> extends SimpleSinglePortInputOperator<T> implements Runnable {
    private static final long serialVersionUID = 201506160829L;
    private static final Logger LOG = LoggerFactory.getLogger(WebSocketInputOperator.class);
    /**
     * Timeout interval for reading from server. 0 or negative indicates no timeout.
     */
    public int readTimeoutMillis = 0;
    //Do not make this @NotNull since null is a valid value for some child classes
    private URI uri;
    private transient AsyncHttpClient client;
    private final transient JsonFactory jsonFactory = new JsonFactory();
    protected final transient ObjectMapper mapper = new ObjectMapper(jsonFactory);
    protected transient WebSocket connection;
    private transient boolean connectionClosed = false;
    private transient volatile boolean shutdown = false;
    private int ioThreadMultiplier = 1;
    protected boolean skipNull = false;

    /**
     * Gets the URI for WebSocket connection
     *
     * @return the URI
     */
    public URI getUri() {
        return uri;
    }

    /**
     * Sets the URI for WebSocket connection
     *
     * @param uri
     */
    public void setUri(URI uri) {
        this.uri = uri;
    }

    /**
     * Gets the IO Thread multiplier for AsyncWebSocket connection
     *
     * @return the IO thread multiplier
     */
    public int getIoThreadMultiplier() {
        return ioThreadMultiplier;
    }

    /**
     * The number of threads to use for the websocket connection.
     *
     * @param ioThreadMultiplier
     */
    public void setIoThreadMultiplier(int ioThreadMultiplier) {
        this.ioThreadMultiplier = ioThreadMultiplier;
    }

    @Override
    public void setup(OperatorContext context) {
        try {
            uri = URI.create(uri.toString()); // force reparse after deserialization

            //client = factory.newWebSocketClient();
            LOG.info("URL: {}", uri);
            // Handle asynchronous websocket client disconnects in future
            // differently to not use a monitor thread.
            shutdown = false;
            monThread = new MonitorThread();
            monThread.start();
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    @Override
    public void teardown() {
        shutdown = true;
        try {
            if (monThread != null) {
                monThread.join();
            }
        } catch (Exception ex) {
            LOG.error("Error joining monitor", ex);
        }

        if (connection != null) {
            connection.close();
        }

        if (client != null) {
            client.close();
        }

        super.teardown();
    }

    @SuppressWarnings("unchecked")
    protected T convertMessage(String message) throws IOException {
        return (T) mapper.readValue(message, Object.class);
    }

    private transient MonitorThread monThread;

    private class MonitorThread extends Thread {
        @Override
        public void run() {
            while (!WebSocketInputOperator.this.shutdown) {
                try {
                    sleep(1000);
                    if (connectionClosed && !WebSocketInputOperator.this.shutdown) {
                        connection.close();
                        WebSocketInputOperator.this.activate(null);
                    }
                } catch (Exception ex) {
                    //swallowing exception
                }
            }
        }

    }

    @Override
    public void run() {
        try {
            connectionClosed = false;
            AsyncHttpClientConfigBean config = new AsyncHttpClientConfigBean();
            config.setIoThreadMultiplier(ioThreadMultiplier);
            config.setApplicationThreadPool(Executors.newCachedThreadPool(new ThreadFactory() {
                private long count = 0;

                @Override
                public Thread newThread(Runnable r) {
                    Thread t = new Thread(r);
                    t.setName(ClassUtils.getShortClassName(this.getClass()) + "-AsyncHttpClient-" + count++);
                    return t;
                }

            }));

            if (client != null) {
                client.closeAsynchronously();
            }

            client = new AsyncHttpClient(config);
            connection = client.prepareGet(uri.toString()).execute(
                    new WebSocketUpgradeHandler.Builder().addWebSocketListener(new WebSocketTextListener() {
                        @Override
                        public void onMessage(String string) {
                            LOG.debug("Got: " + string);
                            try {
                                T o = convertMessage(string);
                                if (!(skipNull && o == null)) {
                                    outputPort.emit(o);
                                }
                            } catch (IOException ex) {
                                LOG.error("Got exception: ", ex);
                            }
                        }

                        @Override
                        public void onOpen(WebSocket ws) {
                            LOG.debug("Connection opened");
                        }

                        @Override
                        public void onClose(WebSocket ws) {
                            LOG.debug("Connection connectionClosed.");
                            connectionClosed = true;
                        }

                        @Override
                        public void onError(Throwable t) {
                            LOG.error("Caught exception", t);
                        }

                    }).build()).get(5, TimeUnit.SECONDS);
        } catch (Exception ex) {
            LOG.error("Error reading from " + uri, ex);
            if (client != null) {
                client.close();
            }
            connectionClosed = true;
        }

    }

}