org.apache.nutch.publisher.rabbitmq.RabbitMQPublisherImpl.java Source code

Introduction

Here is the source code for org.apache.nutch.publisher.rabbitmq.RabbitMQPublisherImpl.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 org.apache.nutch.publisher.rabbitmq;

import java.lang.invoke.MethodHandles;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.StringUtils;
import org.apache.nutch.publisher.NutchPublisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class RabbitMQPublisherImpl implements NutchPublisher {

    private static String EXCHANGE_SERVER;
    private static String EXCHANGE_TYPE;

    private static String HOST;

    private static int PORT;
    private static String VIRTUAL_HOST;
    private static String USERNAME;
    private static String PASSWORD;

    private static String QUEUE_NAME;
    private static boolean QUEUE_DURABLE;
    private static String QUEUE_ROUTING_KEY;

    private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());

    private static Channel channel;

    @Override
    public boolean setConfig(Configuration conf) {
        try {
            EXCHANGE_SERVER = conf.get("rabbitmq.exchange.server", "fetcher_log");
            EXCHANGE_TYPE = conf.get("rabbitmq.exchange.type", "fanout");

            HOST = conf.get("rabbitmq.host", "localhost");
            PORT = conf.getInt("rabbitmq.port", 5672);
            VIRTUAL_HOST = conf.get("rabbitmq.virtualhost", null);
            USERNAME = conf.get("rabbitmq.username", null);
            PASSWORD = conf.get("rabbitmq.password", null);

            QUEUE_NAME = conf.get("rabbitmq.queue.name", "fanout.queue");
            QUEUE_DURABLE = conf.getBoolean("rabbitmq.queue.durable", true);
            QUEUE_ROUTING_KEY = conf.get("rabbitmq.queue.routingkey", "fanout.key");

            ConnectionFactory factory = new ConnectionFactory();
            factory.setHost(HOST);
            factory.setPort(PORT);

            if (VIRTUAL_HOST != null) {
                factory.setVirtualHost(VIRTUAL_HOST);
            }

            if (USERNAME != null) {
                factory.setUsername(USERNAME);
                factory.setPassword(PASSWORD);
            }

            Connection connection = factory.newConnection();
            channel = connection.createChannel();
            channel.exchangeDeclare(EXCHANGE_SERVER, EXCHANGE_TYPE);
            channel.queueDeclare(QUEUE_NAME, QUEUE_DURABLE, false, false, null);
            channel.queueBind(QUEUE_NAME, EXCHANGE_SERVER, QUEUE_ROUTING_KEY);

            LOG.info("Configured RabbitMQ publisher");
            return true;
        } catch (Exception e) {
            LOG.error("Could not initialize RabbitMQ publisher - {}", StringUtils.stringifyException(e));
            return false;
        }

    }

    @Override
    public void publish(Object event, Configuration conf) {
        try {
            channel.basicPublish(EXCHANGE_SERVER, QUEUE_ROUTING_KEY, null, getJSONString(event).getBytes());
        } catch (Exception e) {
            LOG.error("Error occured while publishing - {}", StringUtils.stringifyException(e));
        }
    }

    private String getJSONString(Object obj) {
        ObjectMapper mapper = new ObjectMapper();
        try {
            return mapper.writeValueAsString(obj);
        } catch (JsonProcessingException e) {
            LOG.error("Error converting event object to JSON String - {}", StringUtils.stringifyException(e));
        }
        return null;
    }

    @Override
    public void setConf(Configuration arg0) {

    }

    @Override
    public Configuration getConf() {
        return null;
    }

}