javax.jms.QueueRequestor.java Source code

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Here is the source code for javax.jms.QueueRequestor.java

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package javax.jms;

/** The {@code QueueRequestor} helper class simplifies
  * making service requests.
  *
  * <P>The {@code QueueRequestor} constructor is given a non-transacted 
  * {@code QueueSession} and a destination {@code Queue}. It creates a
  * {@code TemporaryQueue} for the responses and provides a 
  * {@code request} method that sends the request message and waits 
  * for its reply.
  * <p>
  * This is a very basic request/reply abstraction which assumes the session 
  * is non-transacted with a delivery mode of either AUTO_ACKNOWLEDGE or 
  * DUPS_OK_ACKNOWLEDGE. It is expected that most applications will create 
  * less basic implementations.
  *
  * @see javax.jms.TopicRequestor
  * 
  * @version JMS 2.0
  * @since JMS 1.0
  * 
  */

public class QueueRequestor {

    QueueSession session; // The queue session the queue belongs to.
    TemporaryQueue tempQueue;
    QueueSender sender;
    QueueReceiver receiver;

    /** Constructor for the {@code QueueRequestor} class.
      *  
      * <P>This implementation assumes the session parameter to be non-transacted,
      * with a delivery mode of either {@code AUTO_ACKNOWLEDGE} or 
      * {@code DUPS_OK_ACKNOWLEDGE}.
      *
      * @param session the {@code QueueSession} the queue belongs to
      * @param queue the queue to perform the request/reply call on
      *  
      * @exception JMSException if the JMS provider fails to create the
      *                         {@code QueueRequestor} due to some internal
      *                         error.
      * @exception InvalidDestinationException if an invalid queue is specified.
      */

    public QueueRequestor(QueueSession session, Queue queue) throws JMSException {

        if (queue == null)
            throw new InvalidDestinationException("queue==null");

        this.session = session;
        tempQueue = session.createTemporaryQueue();
        sender = session.createSender(queue);
        receiver = session.createReceiver(tempQueue);
    }

    /** Sends a request and waits for a reply. The temporary queue is used for
      * the {@code JMSReplyTo} destination, and only one reply per request 
      * is expected.
      *  
      * @param message the message to send
      *  
      * @return the reply message
      *  
      * @exception JMSException if the JMS provider fails to complete the
      *                         request due to some internal error.
      */

    public Message request(Message message) throws JMSException {
        message.setJMSReplyTo(tempQueue);
        sender.send(message);
        return (receiver.receive());
    }

    /** Closes the {@code QueueRequestor} and its session.
      *
      * <P>Since a provider may allocate some resources on behalf of a 
      * {@code QueueRequestor} outside the Java virtual machine, clients 
      * should close them when they 
      * are not needed. Relying on garbage collection to eventually reclaim 
      * these resources may not be timely enough.
      *  
      * <P>Note that this method closes the {@code QueueSession} object 
      * passed to the {@code QueueRequestor} constructor.
      *
      * @exception JMSException if the JMS provider fails to close the
      *                         {@code QueueRequestor} due to some internal
      *                         error.
      */

    public void close() throws JMSException {

        // publisher and consumer created by constructor are implicitly closed.
        session.close();
        tempQueue.delete();
    }
}