eu.semaine.jms.receiver
Class Receiver

java.lang.Object
  eu.semaine.jms.IOBase
      eu.semaine.jms.receiver.Receiver

All Implemented Interfaces:

javax.jms.MessageListener

Direct Known Subclasses:

BytesReceiver, FeatureReceiver, JMSLogReader, XMLReceiver

public class Receiver
extends IOBase
implements javax.jms.MessageListener

This class handles the common part to all message receivers in the SEMAINE system. Two models of use are possible:

• synchronous API: client code calls the methods receive(), receive(long) or receiveNoWait() directly;
• asynchronous API: client code registers a SEMAINEMessageAvailableListener; whenever a new message arrives, the Receiver thread will call that listener's SEMAINEMessageAvailableListener.messageAvailableFrom(Receiver) method. The listener code then calls the Receiver's getMessage() method from the thread that should actually do the processing of the message. Note that in the asynchronous API, the Receiver will block until getMessage() was called.

The Receiver itself covers basic text messages only. Subclasses should override createSEMAINEMessage(Message) to do a meaningful analysis of the JMS message in terms of a suitable subclass of SEMAINEMessage.

Author:

marc

Nested Class Summary

Nested classes/interfaces inherited from class eu.semaine.jms.IOBase

IOBase.Event

Field Summary

protected javax.jms.MessageConsumer	consumer
protected SEMAINEMessageAvailableListener	listener
protected JMSLogger	log
protected SEMAINEMessage	message

Fields inherited from class eu.semaine.jms.IOBase

connection, isConnectionStarted, jmsPassword, jmsUrl, jmsUser, session, topic

Constructor Summary

Receiver(java.lang.String topicName)
Create a receiver that will listen for all messages in the given Topic.

Receiver(java.lang.String topicName, java.lang.String messageSelector)
Create a receiver that will listen only to the messages in the given Topic that will pass the given messageSelector.

Method Summary

protected SEMAINEMessage	createSEMAINEMessage(javax.jms.Message message) Create a SEMAINE message from the given JMS message.
SEMAINEMessage	getMessage()
SEMAINEMessageAvailableListener	getMessageListener()
java.lang.String	getMessageSelector() Get the message selector pattern active in this receiver to filter messages.
static void	main(java.lang.String[] args)
boolean	notPickedUp()
void	onMessage(javax.jms.Message m)
SEMAINEMessage	receive() Receives the next message produced for this message consumer.
SEMAINEMessage	receive(long timeout) Receives the next message that arrives within the specified timeout interval.
SEMAINEMessage	receiveNoWait() Receives the next message if one is immediately available.
void	setMessageListener(SEMAINEMessageAvailableListener aListener)

Methods inherited from class eu.semaine.jms.IOBase

getConnection, getJMSUrl, getSession, getTopic, getTopicName, startConnection

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

consumer

protected javax.jms.MessageConsumer consumer

listener

protected SEMAINEMessageAvailableListener listener

log

protected JMSLogger log

message

protected SEMAINEMessage message

Constructor Detail

Receiver

public Receiver(java.lang.String topicName)
         throws javax.jms.JMSException

Create a receiver that will listen for all messages in the given Topic.

Parameters:

topic - the name of the JMS Topic to listen to.

Throws:

javax.jms.JMSException

Receiver

public Receiver(java.lang.String topicName,
                java.lang.String messageSelector)
         throws javax.jms.JMSException

Create a receiver that will listen only to the messages in the given Topic that will pass the given messageSelector.

Parameters:

topicName - the name of the JMS Topic to listen to.

messageSelector - a message selector expression, see e.g. http://java.sun.com/javaee/5/docs/api/javax/jms/Message.html for the detailed description.

Throws:

javax.jms.JMSException

Method Detail

getMessageSelector

public java.lang.String getMessageSelector()
                                    throws javax.jms.JMSException

Get the message selector pattern active in this receiver to filter messages.

Returns:

a string representation of the selector pattern.

Throws:

javax.jms.JMSException

createSEMAINEMessage

protected SEMAINEMessage createSEMAINEMessage(javax.jms.Message message)
                                       throws MessageFormatException

Create a SEMAINE message from the given JMS message. Subclasses may want to override this in order to provide subclasses of SEMAINEMessage for their data.

Parameters:

message - the JMS method to convert into a SEMAINE message.

Throws:

MessageFormatException - if the message format is problematic

java.lang.NullPointerException - if message is null.

receive

public SEMAINEMessage receive()
                       throws javax.jms.JMSException

Receives the next message produced for this message consumer. This call blocks indefinitely until a message is produced or until this message consumer is closed.

Returns:

the next message produced for this message consumer, or null if this message consumer is concurrently closed

Throws:

javax.jms.JMSException - if the JMS provider fails to receive the next message due to some internal error.

receive

public SEMAINEMessage receive(long timeout)
                       throws javax.jms.JMSException

Receives the next message that arrives within the specified timeout interval. This call blocks until a message arrives, the timeout expires, or this message consumer is closed. A timeout of zero never expires, and the call blocks indefinitely.

Parameters:

timeout - the timeout value (in milliseconds)

Returns:

the next message produced for this message consumer, or null if the timeout expires or this message consumer is concurrently closed

Throws:

javax.jms.JMSException - if the JMS provider fails to receive the next message due to some internal error.

receiveNoWait

public SEMAINEMessage receiveNoWait()
                             throws javax.jms.JMSException

Receives the next message if one is immediately available.

Returns:

the next message produced for this message consumer, or null if one is not available

Throws:

javax.jms.JMSException - if the JMS provider fails to receive the next message due to some internal error.

setMessageListener

public void setMessageListener(SEMAINEMessageAvailableListener aListener)
                        throws javax.jms.JMSException

Throws:

javax.jms.JMSException

getMessageListener

public SEMAINEMessageAvailableListener getMessageListener()

onMessage

public void onMessage(javax.jms.Message m)

Specified by:

onMessage in interface javax.jms.MessageListener

getMessage

public SEMAINEMessage getMessage()

notPickedUp

public boolean notPickedUp()

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Throws:

java.lang.Exception