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ActiveMQ example source code file (ActiveMQConnectionConsumer.java)

This example ActiveMQ source code file (ActiveMQConnectionConsumer.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

activemqconnectionconsumer, activemqconnectionconsumer, activemqqueuesession, activemqqueuesession, activemqsession, activemqtopicsession, connectionconsumer, consumerinfo, jmsexception, jmsexception, serversessionpool, serversessionpool, session, string, util

The ActiveMQ ActiveMQConnectionConsumer.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;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

import javax.jms.ConnectionConsumer;
import javax.jms.IllegalStateException;
import javax.jms.JMSException;
import javax.jms.ServerSession;
import javax.jms.ServerSessionPool;
import javax.jms.Session;

import org.apache.activemq.command.ConsumerInfo;
import org.apache.activemq.command.MessageDispatch;

/**
 * For application servers, <CODE>Connection objects provide a special
 * facility for creating a <CODE>ConnectionConsumer (optional). The
 * messages it is to consume are specified by a <CODE>Destination and a
 * message selector. In addition, a <CODE>ConnectionConsumer must be
 * given a <CODE>ServerSessionPool to use for processing its messages.
 * <p/>
 * <P>
 * Normally, when traffic is light, a <CODE>ConnectionConsumer gets a
 * <CODE>ServerSession from its pool, loads it with a single message,
 * and starts it. As traffic picks up, messages can back up. If this happens, a
 * <CODE>ConnectionConsumer can load each ServerSession
 * with more than one message. This reduces the thread context switches and
 * minimizes resource use at the expense of some serialization of message
 * processing.
 * 
 * @see javax.jms.Connection#createConnectionConsumer
 * @see javax.jms.Connection#createDurableConnectionConsumer
 * @see javax.jms.QueueConnection#createConnectionConsumer
 * @see javax.jms.TopicConnection#createConnectionConsumer
 * @see javax.jms.TopicConnection#createDurableConnectionConsumer
 */

public class ActiveMQConnectionConsumer implements ConnectionConsumer, ActiveMQDispatcher {

    private ActiveMQConnection connection;
    private ServerSessionPool sessionPool;
    private ConsumerInfo consumerInfo;
    private boolean closed;

    /**
     * Create a ConnectionConsumer
     * 
     * @param theConnection
     * @param theSessionPool
     * @param theConsumerInfo
     * @throws JMSException
     */
    protected ActiveMQConnectionConsumer(ActiveMQConnection theConnection, ServerSessionPool theSessionPool, ConsumerInfo theConsumerInfo) throws JMSException {
        this.connection = theConnection;
        this.sessionPool = theSessionPool;
        this.consumerInfo = theConsumerInfo;

        this.connection.addConnectionConsumer(this);
        this.connection.addDispatcher(consumerInfo.getConsumerId(), this);
        this.connection.asyncSendPacket(this.consumerInfo);
    }

    /**
     * Gets the server session pool associated with this connection consumer.
     * 
     * @return the server session pool used by this connection consumer
     * @throws JMSException if the JMS provider fails to get the server session
     *                 pool associated with this consumer due to some internal
     *                 error.
     */

    public ServerSessionPool getServerSessionPool() throws JMSException {
        if (closed) {
            throw new IllegalStateException("The Connection Consumer is closed");
        }
        return this.sessionPool;
    }

    /**
     * Closes the connection consumer. <p/>
     * <P>
     * Since a provider may allocate some resources on behalf of a connection
     * consumer outside the Java virtual machine, clients should close these
     * resources when they are not needed. Relying on garbage collection to
     * eventually reclaim these resources may not be timely enough.
     * 
     * @throws JMSException
     */

    public void close() throws JMSException {
        if (!closed) {
            dispose();
            this.connection.asyncSendPacket(this.consumerInfo.createRemoveCommand());
        }

    }

    public void dispose() {
        if (!closed) {
            this.connection.removeDispatcher(consumerInfo.getConsumerId());
            this.connection.removeConnectionConsumer(this);
            closed = true;
        }
    }

    public void dispatch(MessageDispatch messageDispatch) {
        try {
            messageDispatch.setConsumer(this);

            ServerSession serverSession = sessionPool.getServerSession();
            Session s = serverSession.getSession();
            ActiveMQSession session = null;

            if (s instanceof ActiveMQSession) {
                session = (ActiveMQSession)s;
            } else if (s instanceof ActiveMQTopicSession) {
                ActiveMQTopicSession topicSession = (ActiveMQTopicSession)s;
                session = (ActiveMQSession)topicSession.getNext();
            } else if (s instanceof ActiveMQQueueSession) {
                ActiveMQQueueSession queueSession = (ActiveMQQueueSession)s;
                session = (ActiveMQSession)queueSession.getNext();
            } else {
                connection.onClientInternalException(new JMSException("Session pool provided an invalid session type: " + s.getClass()));
                return;
            }

            session.dispatch(messageDispatch);
            serverSession.start();
        } catch (JMSException e) {
            connection.onAsyncException(e);
        }
    }

    public String toString() {
        return "ActiveMQConnectionConsumer { value=" + consumerInfo.getConsumerId() + " }";
    }

    public void clearMessagesInProgress() {
        // future: may want to deal with rollback of in progress messages to track re deliveries
        // before indicating that all is complete.        
        // Till there is a need, lets immediately allow dispatch
        this.connection.transportInterruptionProcessingComplete();
    }
}

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