org.apache.activemq

Class ActiveMQMessageConsumer

java.lang.Object

org.apache.activemq.ActiveMQMessageConsumer

All Implemented Interfaces:

MessageConsumer, ActiveMQDispatcher, StatsCapable, MessageAvailableConsumer

Direct Known Subclasses:

ActiveMQQueueReceiver, ActiveMQTopicSubscriber

public class ActiveMQMessageConsumer
extends Object
implements MessageAvailableConsumer, StatsCapable, ActiveMQDispatcher

A client uses a MessageConsumer object to receive messages from a destination. A MessageConsumer object is created by passing a Destination object to a message-consumer creation method supplied by a session.

MessageConsumer is the parent interface for all message consumers.

A message consumer can be created with a message selector. A message selector allows the client to restrict the messages delivered to the message consumer to those that match the selector.

A client may either synchronously receive a message consumer's messages or have the consumer asynchronously deliver them as they arrive.

For synchronous receipt, a client can request the next message from a message consumer using one of its receive methods. There are several variations of receive that allow a client to poll or wait for the next message.

For asynchronous delivery, a client can register a MessageListener object with a message consumer. As messages arrive at the message consumer, it delivers them by calling the MessageListener's onMessage method.

It is a client programming error for a MessageListener to throw an exception.

See Also:

MessageConsumer, QueueReceiver, TopicSubscriber, Session

Field Summary

Fields

Modifier and Type	Field and Description
protected LinkedList<MessageDispatch>	deliveredMessages
protected ConsumerInfo	info
protected ActiveMQSession	session
protected MessageDispatchChannel	unconsumedMessages

Constructor Summary

Constructors

Constructor and Description
ActiveMQMessageConsumer(ActiveMQSession session, ConsumerId consumerId, ActiveMQDestination dest, String name, String selector, int prefetch, int maximumPendingMessageCount, boolean noLocal, boolean browser, boolean dispatchAsync, MessageListener messageListener) Create a MessageConsumer

Method Summary

Modifier and Type	Method and Description
void	acknowledge() Acknowledge all the messages that have been delivered to the client up to this point.
protected void	checkClosed()
protected void	checkMessageListener()
void	close() Closes the message consumer.
void	commit()
void	dispatch(MessageDispatch md)
void	dispose()
MessageAvailableListener	getAvailableListener() Gets the listener used to notify synchronous consumers that there is a message available so that the MessageConsumer.receiveNoWait() can be called.
ConsumerId	getConsumerId()
String	getConsumerName()
JMSConsumerStatsImpl	getConsumerStats()
protected ActiveMQDestination	getDestination()
IOException	getFailureError()
long	getLastDeliveredSequenceId()
MessageListener	getMessageListener() Gets the message consumer's MessageListener.
String	getMessageSelector() Gets this message consumer's message selector expression.
int	getMessageSize()
long	getOptimizedAckScheduledAckInterval()
int	getPrefetchNumber()
RedeliveryPolicy	getRedeliveryPolicy()
StatsImpl	getStats()
MessageTransformer	getTransformer()
boolean	hasMessageListener()
protected boolean	isBrowser() Retrieve is a browser
boolean	isConsumerExpiryCheckEnabled()
boolean	isDurableSubscriber()
boolean	isInUse(ActiveMQTempDestination destination)
protected boolean	isNoLocal()
boolean	iterate() Delivers a message to the message listener.
Message	receive() Receives the next message produced for this message consumer.
Message	receive(long timeout) Receives the next message that arrives within the specified timeout interval.
Message	receiveNoWait() Receives the next message if one is immediately available.
void	rollback()
protected void	sendPullCommand(long timeout) If we have a zero prefetch specified then send a pull command to the broker to pull a message we are about to receive
void	setAvailableListener(MessageAvailableListener availableListener) Sets the listener used to notify synchronous consumers that there is a message available so that the MessageConsumer.receiveNoWait() can be called.
void	setConsumerExpiryCheckEnabled(boolean consumerExpiryCheckEnabled)
void	setFailureError(IOException failureError)
void	setMessageListener(MessageListener listener) Sets the message consumer's MessageListener.
protected void	setOptimizeAcknowledge(boolean value)
void	setOptimizedAckScheduledAckInterval(long optimizedAckScheduledAckInterval)
protected void	setPrefetchSize(int prefetch)
void	setRedeliveryPolicy(RedeliveryPolicy redeliveryPolicy) Sets the redelivery policy used when messages are redelivered
void	setTransformer(MessageTransformer transformer) Sets the transformer used to transform messages before they are sent on to the JMS bus
void	start()
void	stop()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

session

protected final ActiveMQSession session

info

protected final ConsumerInfo info

unconsumedMessages

protected final MessageDispatchChannel unconsumedMessages

deliveredMessages

protected final LinkedList<MessageDispatch> deliveredMessages

Constructor Detail

ActiveMQMessageConsumer

public ActiveMQMessageConsumer(ActiveMQSession session,
                               ConsumerId consumerId,
                               ActiveMQDestination dest,
                               String name,
                               String selector,
                               int prefetch,
                               int maximumPendingMessageCount,
                               boolean noLocal,
                               boolean browser,
                               boolean dispatchAsync,
                               MessageListener messageListener)
                        throws JMSException

Create a MessageConsumer

Parameters:

session -

dest -

name -

selector -

prefetch -

maximumPendingMessageCount -

noLocal -

browser -

dispatchAsync -

messageListener -

Throws:

JMSException

Method Detail

getStats

public StatsImpl getStats()

Specified by:

getStats in interface StatsCapable

Returns:

the Stats for this object

getConsumerStats

public JMSConsumerStatsImpl getConsumerStats()

getRedeliveryPolicy

public RedeliveryPolicy getRedeliveryPolicy()

setRedeliveryPolicy

public void setRedeliveryPolicy(RedeliveryPolicy redeliveryPolicy)

Sets the redelivery policy used when messages are redelivered

getTransformer

public MessageTransformer getTransformer()

setTransformer

public void setTransformer(MessageTransformer transformer)

Sets the transformer used to transform messages before they are sent on to the JMS bus

getConsumerId

public ConsumerId getConsumerId()

Returns:

Returns the value.

getConsumerName

public String getConsumerName()

Returns:

the consumer name - used for durable consumers

isNoLocal

protected boolean isNoLocal()

Returns:

true if this consumer does not accept locally produced messages

isBrowser

protected boolean isBrowser()

Retrieve is a browser

Returns:

true if a browser

getDestination

protected ActiveMQDestination getDestination()

Returns:

ActiveMQDestination

getPrefetchNumber

public int getPrefetchNumber()

Returns:

Returns the prefetchNumber.

isDurableSubscriber

public boolean isDurableSubscriber()

Returns:

true if this is a durable topic subscriber

getMessageSelector

public String getMessageSelector()
                          throws JMSException

Gets this message consumer's message selector expression.

Specified by:

getMessageSelector in interface MessageConsumer

Returns:

this message consumer's message selector, or null if no message selector exists for the message consumer (that is, if the message selector was not set or was set to null or the empty string)

Throws:

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

getMessageListener

public MessageListener getMessageListener()
                                   throws JMSException

Gets the message consumer's MessageListener.

Specified by:

getMessageListener in interface MessageConsumer

Returns:

the listener for the message consumer, or null if no listener is set

Throws:

JMSException - if the JMS provider fails to get the message listener due to some internal error.

See Also:

MessageConsumer.setMessageListener(javax.jms.MessageListener)

setMessageListener

public void setMessageListener(MessageListener listener)
                        throws JMSException

Sets the message consumer's MessageListener.

Setting the message listener to null is the equivalent of unsetting the message listener for the message consumer.

The effect of calling MessageConsumer.setMessageListener while messages are being consumed by an existing listener or the consumer is being used to consume messages synchronously is undefined.

Specified by:

setMessageListener in interface MessageConsumer

Parameters:

listener - the listener to which the messages are to be delivered

Throws:

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

See Also:

MessageConsumer.getMessageListener()

getAvailableListener

public MessageAvailableListener getAvailableListener()

Description copied from interface: MessageAvailableConsumer

Gets the listener used to notify synchronous consumers that there is a message available so that the MessageConsumer.receiveNoWait() can be called.

Specified by:

getAvailableListener in interface MessageAvailableConsumer

setAvailableListener

public void setAvailableListener(MessageAvailableListener availableListener)

Sets the listener used to notify synchronous consumers that there is a message available so that the MessageConsumer.receiveNoWait() can be called.

Specified by:

setAvailableListener in interface MessageAvailableConsumer

receive

public Message receive()
                throws 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.

If this receive is done within a transaction, the consumer retains the message until the transaction commits.

Specified by:

receive in interface MessageConsumer

Returns:

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

Throws:

JMSException

receive

public Message receive(long timeout)
                throws 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.

Specified by:

receive in interface MessageConsumer

Parameters:

timeout - the timeout value (in milliseconds), a time out of zero never expires.

Returns:

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

Throws:

JMSException

receiveNoWait

public Message receiveNoWait()
                      throws JMSException

Receives the next message if one is immediately available.

Specified by:

receiveNoWait in interface MessageConsumer

Returns:

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

Throws:

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

close

public void close()
           throws JMSException

Closes the message consumer.

Since a provider may allocate some resources on behalf of a MessageConsumer 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.

This call blocks until a receive or message listener in progress has completed. A blocked message consumer receive call returns null when this message consumer is closed.

Specified by:

close in interface MessageConsumer

Throws:

JMSException - if the JMS provider fails to close the consumer due to some internal error.

dispose

public void dispose()
             throws JMSException

Throws:

JMSException

checkClosed

protected void checkClosed()
                    throws IllegalStateException

Throws:

IllegalStateException

sendPullCommand

protected void sendPullCommand(long timeout)
                        throws JMSException

If we have a zero prefetch specified then send a pull command to the broker to pull a message we are about to receive

Throws:

JMSException

checkMessageListener

protected void checkMessageListener()
                             throws JMSException

Throws:

JMSException

setOptimizeAcknowledge

protected void setOptimizeAcknowledge(boolean value)

setPrefetchSize

protected void setPrefetchSize(int prefetch)

acknowledge

public void acknowledge()
                 throws JMSException

Acknowledge all the messages that have been delivered to the client up to this point.

Throws:

JMSException

commit

public void commit()
            throws JMSException

Throws:

JMSException

rollback

public void rollback()
              throws JMSException

Throws:

JMSException

dispatch

public void dispatch(MessageDispatch md)

Specified by:

dispatch in interface ActiveMQDispatcher

getMessageSize

public int getMessageSize()

start

public void start()
           throws JMSException

Throws:

JMSException

stop

public void stop()

toString

public String toString()

Overrides:

toString in class Object

iterate

public boolean iterate()

Delivers a message to the message listener.

Returns:

true if another execution is needed.

Throws:

JMSException

isInUse

public boolean isInUse(ActiveMQTempDestination destination)

getLastDeliveredSequenceId

public long getLastDeliveredSequenceId()

getFailureError

public IOException getFailureError()

setFailureError

public void setFailureError(IOException failureError)

getOptimizedAckScheduledAckInterval

public long getOptimizedAckScheduledAckInterval()

Returns:

the optimizedAckScheduledAckInterval

setOptimizedAckScheduledAckInterval

public void setOptimizedAckScheduledAckInterval(long optimizedAckScheduledAckInterval)
                                         throws JMSException

Parameters:

optimizedAckScheduledAckInterval - the optimizedAckScheduledAckInterval to set

Throws:

JMSException

hasMessageListener

public boolean hasMessageListener()

isConsumerExpiryCheckEnabled

public boolean isConsumerExpiryCheckEnabled()

setConsumerExpiryCheckEnabled

public void setConsumerExpiryCheckEnabled(boolean consumerExpiryCheckEnabled)