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

Java tutorial

Introduction

Here is the source code for com.datatorrent.lib.io.WebSocketOutputOperator.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.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

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;
import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.common.util.BaseOperator;

/**
 * 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 Output
 * @category Output
 * @tags http, websocket
 *
 * @param <T> tuple type
 * @since 0.3.2
 */
@org.apache.hadoop.classification.InterfaceStability.Evolving
public class WebSocketOutputOperator<T> extends BaseOperator {
    private static final Logger LOG = LoggerFactory.getLogger(WebSocketOutputOperator.class);
    //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 int ioThreadMultiplier = 1;
    private int numRetries = 3;
    private int waitMillisRetry = 5000;
    private long count = 0;

    /**
     * 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 milliseconds to wait before retrying connection
     *
     * @return wait in milliseconds
     */
    public int getWaitMillisRetry() {
        return waitMillisRetry;
    }

    /**
     * Sets the milliseconds to wait before retrying connection
     *
     * @param waitMillisRetry
     */
    public void setWaitMillisRetry(int waitMillisRetry) {
        this.waitMillisRetry = waitMillisRetry;
    }

    /**
     * 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;
    }

    /**
     * Gets the number of retries of connection before the giving up
     *
     * @return the number of retries
     */
    public int getNumRetries() {
        return numRetries;
    }

    /**
     * Sets the number of retries of connection before the giving up
     *
     * @param numRetries
     */
    public void setNumRetries(int numRetries) {
        this.numRetries = numRetries;
    }

    /**
     * The input port
     */
    public final transient DefaultInputPort<T> input = new DefaultInputPort<T>() {
        @Override
        public void process(T t) {
            int countTries = 0;
            while (true) {
                try {
                    if (connection == null || !connection.isOpen()) {
                        LOG.warn("Connection is closed. Reconnecting...");
                        client.close();
                        openConnection();
                    }
                    connection.sendMessage(convertMapToMessage(t));
                    break;
                } catch (Exception ex) {
                    if (++countTries < numRetries) {
                        LOG.debug("Caught exception", ex);
                        LOG.warn("Send message failed ({}). Retrying ({}).", ex.getMessage(), countTries);
                        if (connection != null) {
                            connection.close();
                        }
                        if (waitMillisRetry > 0) {
                            try {
                                Thread.sleep(waitMillisRetry);
                            } catch (InterruptedException ex1) {
                                // continue
                            }
                        }
                    } else {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }

    };

    private void openConnection() throws IOException, ExecutionException, InterruptedException, TimeoutException {
        final AsyncHttpClientConfigBean config = new AsyncHttpClientConfigBean();
        config.setIoThreadMultiplier(ioThreadMultiplier);
        config.setApplicationThreadPool(Executors.newCachedThreadPool(new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
                Thread t = new Thread(r);
                t.setName(ClassUtils.getShortClassName(this.getClass()) + "-AsyncHttpClient-" + count++);
                return t;
            }

        }));
        client = new AsyncHttpClient(config);
        uri = URI.create(uri.toString()); // force reparse after deserialization
        LOG.info("Opening URL: {}", uri);
        connection = client.prepareGet(uri.toString())
                .execute(new WebSocketUpgradeHandler.Builder().addWebSocketListener(new WebSocketTextListener() {
                    @Override
                    public void onMessage(String string) {
                    }

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

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

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

                }).build()).get(5, TimeUnit.SECONDS);
    }

    @Override
    public void setup(OperatorContext context) {
        try {
            openConnection();
        } catch (Exception ex) {
            LOG.warn("Cannot establish connection:", ex);
        }
    }

    @Override
    public void teardown() {
        super.teardown();
        if (client != null) {
            client.close();
        }
    }

    public String convertMapToMessage(T t) throws IOException {
        return mapper.writeValueAsString(t);
    }

}