ActiveMQ example source code file (VMTransportFactory.java)

This example ActiveMQ source code file (VMTransportFactory.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

brokerfactoryhandler, brokerservice, brokerservice, concurrenthashmap, io, ioexception, map, net, network, string, string, threading, threads, transport, transportconnector, transportconnector, uri, util, vmtransportserver, vmtransportserver

The ActiveMQ VMTransportFactory.java source code

/**
 * 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.activemq.transport.vm;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.activemq.broker.BrokerFactory;
import org.apache.activemq.broker.BrokerFactoryHandler;
import org.apache.activemq.broker.BrokerRegistry;
import org.apache.activemq.broker.BrokerService;
import org.apache.activemq.broker.TransportConnector;
import org.apache.activemq.transport.MarshallingTransportFilter;
import org.apache.activemq.transport.Transport;
import org.apache.activemq.transport.TransportFactory;
import org.apache.activemq.transport.TransportServer;
import org.apache.activemq.util.IOExceptionSupport;
import org.apache.activemq.util.IntrospectionSupport;
import org.apache.activemq.util.ServiceSupport;
import org.apache.activemq.util.URISupport;
import org.apache.activemq.util.URISupport.CompositeData;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;

public class VMTransportFactory extends TransportFactory {
    
    public static final ConcurrentHashMap<String, BrokerService> BROKERS = new ConcurrentHashMap();
    public static final ConcurrentHashMap<String, TransportConnector> CONNECTORS = new ConcurrentHashMap();
    public static final ConcurrentHashMap<String, VMTransportServer> SERVERS = new ConcurrentHashMap();
    private static final Logger LOG = LoggerFactory.getLogger(VMTransportFactory.class);
    
    BrokerFactoryHandler brokerFactoryHandler;

    public Transport doConnect(URI location) throws Exception {
        return VMTransportServer.configure(doCompositeConnect(location));
    }

    public Transport doCompositeConnect(URI location) throws Exception {
        URI brokerURI;
        String host;
        Map<String, String> options;
        boolean create = true;
        int waitForStart = -1;
        CompositeData data = URISupport.parseComposite(location);
        if (data.getComponents().length == 1 && "broker".equals(data.getComponents()[0].getScheme())) {
            brokerURI = data.getComponents()[0];
            CompositeData brokerData = URISupport.parseComposite(brokerURI);
            host = (String)brokerData.getParameters().get("brokerName");
            if (host == null) {
                host = "localhost";
            }
            if (brokerData.getPath() != null) {
                host = brokerData.getPath();
            }
            options = data.getParameters();
            location = new URI("vm://" + host);
        } else {
            // If using the less complex vm://localhost?broker.persistent=true
            // form
            try {
                host = extractHost(location);
                options = URISupport.parseParameters(location);
                String config = (String)options.remove("brokerConfig");
                if (config != null) {
                    brokerURI = new URI(config);
                } else {
                    Map brokerOptions = IntrospectionSupport.extractProperties(options, "broker.");
                    brokerURI = new URI("broker://()/" + host + "?"
                                        + URISupport.createQueryString(brokerOptions));
                }
                if ("false".equals(options.remove("create"))) {
                    create = false;
                }
                String waitForStartString = options.remove("waitForStart");
                if (waitForStartString != null) {
                    waitForStart = Integer.parseInt(waitForStartString);
                }
            } catch (URISyntaxException e1) {
                throw IOExceptionSupport.create(e1);
            }
            location = new URI("vm://" + host);
        }
        if (host == null) {
            host = "localhost";
        }
        VMTransportServer server = SERVERS.get(host);
        // validate the broker is still active
        if (!validateBroker(host) || server == null) {
            BrokerService broker = null;
            // Synchronize on the registry so that multiple concurrent threads
            // doing this do not think that the broker has not been created and
            // cause multiple brokers to be started.
            synchronized (BrokerRegistry.getInstance().getRegistryMutext()) {
                broker = lookupBroker(BrokerRegistry.getInstance(), host, waitForStart);
                if (broker == null) {
                    if (!create) {
                        throw new IOException("Broker named '" + host + "' does not exist.");
                    }
                    try {
                        if (brokerFactoryHandler != null) {
                            broker = brokerFactoryHandler.createBroker(brokerURI);
                        } else {
                            broker = BrokerFactory.createBroker(brokerURI);
                        }
                        broker.start();
                        MDC.put("activemq.broker", broker.getBrokerName());
                    } catch (URISyntaxException e) {
                        throw IOExceptionSupport.create(e);
                    }
                    BROKERS.put(host, broker);
                    BrokerRegistry.getInstance().getRegistryMutext().notifyAll();
                }

                server = SERVERS.get(host);
                if (server == null) {
                    server = (VMTransportServer)bind(location, true);
                    TransportConnector connector = new TransportConnector(server);
                    connector.setBrokerService(broker);
                    connector.setUri(location);
                    connector.setTaskRunnerFactory(broker.getTaskRunnerFactory());
                    connector.start();
                    CONNECTORS.put(host, connector);
                }

            }
        }

        VMTransport vmtransport = server.connect();
        IntrospectionSupport.setProperties(vmtransport.peer, new HashMap<String,String>(options));
        IntrospectionSupport.setProperties(vmtransport, options);
        Transport transport = vmtransport;
        if (vmtransport.isMarshal()) {
            Map<String, String> optionsCopy = new HashMap(options);
            transport = new MarshallingTransportFilter(transport, createWireFormat(options),
                                                       createWireFormat(optionsCopy));
        }
        if (!options.isEmpty()) {
            throw new IllegalArgumentException("Invalid connect parameters: " + options);
        }
        return transport;
    }

   private static String extractHost(URI location) {
       String host = location.getHost();
       if (host == null || host.length() == 0) {
           host = location.getAuthority();
           if (host == null || host.length() == 0) {
               host = "localhost";
           }
       }
       return host;
    }

/**
    * @param registry
    * @param brokerName
    * @param waitForStart - time in milliseconds to wait for a broker to appear
    * @return
    */
    private BrokerService lookupBroker(final BrokerRegistry registry, final String brokerName, int waitForStart) {
        BrokerService broker = null;
        synchronized(registry.getRegistryMutext()) {
            broker = registry.lookup(brokerName);
            if (broker == null && waitForStart > 0) {
                final long expiry = System.currentTimeMillis() + waitForStart;
                while (broker == null  && expiry > System.currentTimeMillis()) {
                    long timeout = Math.max(0, expiry - System.currentTimeMillis());
                    try {
                        LOG.debug("waiting for broker named: " + brokerName + " to start");
                        registry.getRegistryMutext().wait(timeout);
                    } catch (InterruptedException ignored) {
                    }
                    broker = registry.lookup(brokerName);
                }
            }
        }
        return broker;
    }

    public TransportServer doBind(URI location) throws IOException {
        return bind(location, false);
    }

    /**
     * @param location
     * @return the TransportServer
     * @throws IOException
     */
    private TransportServer bind(URI location, boolean dispose) throws IOException {
        String host = extractHost(location);
        LOG.debug("binding to broker: " + host);
        VMTransportServer server = new VMTransportServer(location, dispose);
        Object currentBoundValue = SERVERS.get(host);
        if (currentBoundValue != null) {
            throw new IOException("VMTransportServer already bound at: " + location);
        }
        SERVERS.put(host, server);
        return server;
    }

    public static void stopped(VMTransportServer server) {
        String host = extractHost(server.getBindURI());
        stopped(host);
    }

    public static void stopped(String host) {
        SERVERS.remove(host);
        TransportConnector connector = CONNECTORS.remove(host);
        if (connector != null) {
            LOG.debug("Shutting down VM connectors for broker: " + host);
            ServiceSupport.dispose(connector);
            BrokerService broker = BROKERS.remove(host);
            if (broker != null) {
                ServiceSupport.dispose(broker);
            }
            MDC.remove("activemq.broker");
        }
    }

    public BrokerFactoryHandler getBrokerFactoryHandler() {
        return brokerFactoryHandler;
    }

    public void setBrokerFactoryHandler(BrokerFactoryHandler brokerFactoryHandler) {
        this.brokerFactoryHandler = brokerFactoryHandler;
    }

    private boolean validateBroker(String host) {
        boolean result = true;
        if (BROKERS.containsKey(host) || SERVERS.containsKey(host) || CONNECTORS.containsKey(host)) {
            // check the broker is still in the BrokerRegistry
            TransportConnector connector = CONNECTORS.get(host);
            if (BrokerRegistry.getInstance().lookup(host) == null
                || (connector != null && connector.getBroker().isStopped())) {
                result = false;
                // clean-up
                BROKERS.remove(host);
                SERVERS.remove(host);
                if (connector != null) {
                    CONNECTORS.remove(host);
                    if (connector != null) {
                        ServiceSupport.dispose(connector);
                    }
                }
            }
        }
        return result;
    }
}