in.cs654.chariot.utils.AshvaClient.java Source code

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Here is the source code for in.cs654.chariot.utils.AshvaClient.java

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/*
 * Copyright (c) 2016 Abhilash Kumar and Saurav Kumar.
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package in.cs654.chariot.utils;

import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.QueueingConsumer;
import com.rabbitmq.client.AMQP.BasicProperties;
import in.cs654.chariot.avro.BasicRequest;
import in.cs654.chariot.avro.BasicResponse;
import in.cs654.chariot.ashva.AshvaServer;
import org.apache.avro.io.*;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.UUID;

/**
 * Client class to make calls to Ashva Server
 */
public class AshvaClient {

    private Connection connection;
    private Channel channel;
    private String replyQueueName;
    private QueueingConsumer consumer;
    private static final String requestQueueName = AshvaServer.RPC_QUEUE_NAME;
    private BinaryEncoder encoder = null;
    private BinaryDecoder decoder = null;
    private ByteArrayOutputStream baos;

    /**
     * Constructor to build AshvaClient
     * @param ipAddr IP address of the ashva server
     */
    public AshvaClient(String ipAddr) {
        final ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(ipAddr);
        try {
            connection = factory.newConnection();
            channel = connection.createChannel();
            replyQueueName = channel.queueDeclare().getQueue();
            consumer = new QueueingConsumer(channel);
            channel.basicConsume(replyQueueName, true, consumer);
            baos = new ByteArrayOutputStream();
        } catch (Exception ignore) {
        }
    }

    /**
     * Function to make RPC call to the server
     * @param request to make
     * @return response received
     */
    public BasicResponse call(BasicRequest request) {
        BasicResponse response = ResponseFactory.getEmptyResponse(request);
        final String corrId = UUID.randomUUID().toString();
        final BasicProperties props = new BasicProperties.Builder().correlationId(corrId).replyTo(replyQueueName)
                .build();
        baos.reset();
        final DatumWriter<BasicRequest> avroWriter = new SpecificDatumWriter<BasicRequest>(BasicRequest.class);
        encoder = EncoderFactory.get().binaryEncoder(baos, encoder);
        try {
            avroWriter.write(request, encoder);
            encoder.flush();
            channel.basicPublish("", requestQueueName, props, baos.toByteArray());
        } catch (IOException ignore) {
        }

        while (true) {
            QueueingConsumer.Delivery delivery;
            try {
                delivery = consumer.nextDelivery();
                if (delivery.getProperties().getCorrelationId().equals(corrId)) {
                    final DatumReader<BasicResponse> avroReader = new SpecificDatumReader<BasicResponse>(
                            BasicResponse.class);
                    decoder = DecoderFactory.get().binaryDecoder(delivery.getBody(), decoder);
                    response = avroReader.read(response, decoder);
                    break;
                }
            } catch (Exception ignore) {
            }
        }
        return response;
    }

    public void close() throws IOException {
        connection.close();
    }
}