org.dawnsci.commandserver.core.producer.AliveConsumer.java Source code

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Here is the source code for org.dawnsci.commandserver.core.producer.AliveConsumer.java

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/*
 * Copyright (c) 2012 Diamond Light Source Ltd.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.dawnsci.commandserver.core.producer;

import java.net.InetAddress;
import java.net.URI;
import java.net.UnknownHostException;
import java.util.UUID;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.DeliveryMode;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.jms.Topic;

import org.dawnsci.commandserver.core.ConnectionFactoryFacade;
import org.dawnsci.commandserver.core.application.IConsumerExtension;
import org.dawnsci.commandserver.core.consumer.Constants;
import org.dawnsci.commandserver.core.consumer.ConsumerBean;
import org.dawnsci.commandserver.core.consumer.ConsumerStatus;

import com.fasterxml.jackson.databind.ObjectMapper;

public abstract class AliveConsumer implements IConsumerExtension {

    private URI uri;

    protected Connection aliveConnection;
    protected final String consumerId;
    protected String consumerVersion;

    private boolean active = true;

    private Connection terminateConnection;
    private ConsumerBean cbean;

    protected AliveConsumer() {
        this.consumerId = System.currentTimeMillis() + "_" + UUID.randomUUID().toString();
        this.consumerVersion = "1.0";
    }

    /**
     * 
     * @return the name which the user will see for this consumer.
     */
    public abstract String getName();

    protected void startNotifications() throws Exception {

        if (uri == null)
            throw new NullPointerException("Please set the URI before starting notifications!");
        this.cbean = new ConsumerBean();
        cbean.setStatus(ConsumerStatus.STARTING);
        cbean.setName(getName());
        cbean.setConsumerId(consumerId);
        cbean.setVersion(consumerVersion);
        cbean.setStartTime(System.currentTimeMillis());
        try {
            cbean.setHostName(InetAddress.getLocalHost().getHostName());
        } catch (UnknownHostException e) {
            // Not fatal but would be nice...
            e.printStackTrace();
        }

        System.out.println("Running events on topic " + Constants.ALIVE_TOPIC + " to notify of '" + getName()
                + "' service being available.");

        final Thread aliveThread = new Thread(new Runnable() {
            public void run() {

                try {
                    ConnectionFactory connectionFactory = ConnectionFactoryFacade.createConnectionFactory(uri);
                    aliveConnection = connectionFactory.createConnection();
                    aliveConnection.start();

                    final Session session = aliveConnection.createSession(false, Session.AUTO_ACKNOWLEDGE);
                    final Topic topic = session.createTopic(Constants.ALIVE_TOPIC);
                    final MessageProducer producer = session.createProducer(topic);

                    final ObjectMapper mapper = new ObjectMapper();

                    // Here we are sending the message out to the topic
                    while (isActive()) {
                        try {
                            Thread.sleep(Constants.NOTIFICATION_FREQUENCY);

                            TextMessage temp = session.createTextMessage(mapper.writeValueAsString(cbean));
                            producer.send(temp, DeliveryMode.NON_PERSISTENT, 1, 5000);

                            if (ConsumerStatus.STARTING.equals(cbean.getStatus())) {
                                cbean.setStatus(ConsumerStatus.RUNNING);
                            }

                        } catch (InterruptedException ne) {
                            break;
                        } catch (Exception neOther) {
                            neOther.printStackTrace();
                        }
                    }
                } catch (Exception ne) {
                    ne.printStackTrace();
                    setActive(false);
                }
            }
        });
        aliveThread.setName("Alive Notification Topic");
        aliveThread.setDaemon(true);
        aliveThread.setPriority(Thread.MIN_PRIORITY);
        aliveThread.start();
    }

    protected void createTerminateListener() throws Exception {

        ConnectionFactory connectionFactory = ConnectionFactoryFacade.createConnectionFactory(uri);
        this.terminateConnection = connectionFactory.createConnection();
        terminateConnection.start();

        Session session = terminateConnection.createSession(false, Session.AUTO_ACKNOWLEDGE);

        final Topic topic = session.createTopic(Constants.TERMINATE_CONSUMER_TOPIC);
        final MessageConsumer consumer = session.createConsumer(topic);

        final ObjectMapper mapper = new ObjectMapper();

        MessageListener listener = new MessageListener() {
            public void onMessage(Message message) {
                try {
                    if (message instanceof TextMessage) {
                        TextMessage t = (TextMessage) message;
                        final ConsumerBean bean = mapper.readValue(t.getText(), ConsumerBean.class);

                        if (bean.getStatus().isFinal()) { // Something else already happened
                            terminateConnection.close();
                            return;
                        }

                        if (consumerId.equals(bean.getConsumerId())) {
                            if (bean.getStatus() == ConsumerStatus.REQUEST_TERMINATE) {
                                System.out.println(getName() + " has been requested to terminate and will exit.");
                                cbean.setStatus(ConsumerStatus.REQUEST_TERMINATE);
                                Thread.currentThread().sleep(2500);
                                System.exit(0);
                            }
                        }

                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

        };
        consumer.setMessageListener(listener);

    }

    public void stop() throws Exception {
        if (aliveConnection != null)
            aliveConnection.close();
        if (terminateConnection != null)
            terminateConnection.close();
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    protected final static boolean checkArguments(String[] args, String usage) {

        if (args == null || args.length != 4) {
            System.out.println(usage);
            return false;
        }

        if (!args[0].startsWith("tcp://")) {
            System.out.println(usage);
            return false;
        }

        if ("".equals(args[1])) {
            System.out.println(usage);
            return false;
        }

        if ("".equals(args[2])) {
            System.out.println(usage);
            return false;
        }

        if ("".equals(args[3])) {
            System.out.println(usage);
            return false;
        }

        return true;

    }

    protected URI getUri() {
        return uri;
    }

    protected void setUri(URI uri) {
        this.uri = uri;
    }

}