org.activemq
Class ActiveMQMessageConsumer

java.lang.Object
  org.activemq.ActiveMQMessageConsumer

All Implemented Interfaces:

MessageConsumer, Closeable, StatsCapable

Direct Known Subclasses:

ActiveMQQueueReceiver, ActiveMQTopicSubscriber

public class ActiveMQMessageConsumer
extends Object
implements MessageConsumer, StatsCapable, Closeable

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.

Version:

$Revision: 1.1.1.1 $

See Also:

MessageConsumer, QueueReceiver, TopicSubscriber, Session

Field Summary

protected boolean	browser
protected String	consumerIdentifier
protected String	consumerName
protected int	consumerNumber
protected ActiveMQDestination	destination
protected MemoryBoundedQueue	messageQueue
protected String	messageSelector
protected boolean	noLocal
protected int	prefetchNumber
protected ActiveMQSession	session
protected long	startTime

Constructor Summary

protected

ActiveMQMessageConsumer(ActiveMQSession theSession, ActiveMQDestination dest, String name, String selector, int cnum, int prefetch, boolean noLocalValue, boolean browserValue) Create a MessageConsumer

Method Summary

protected void	checkClosed()
protected void	clearMessagesInProgress()
void	close() Closes the message consumer.
protected String	getConsumerIdentifier()
protected String	getConsumerName()
protected int	getConsumerNumber()
JMSConsumerStatsImpl	getConsumerStats()
protected ActiveMQDestination	getDestination()
long	getLocalMemoryUsage()
MessageListener	getMessageListener() Gets the message consumer's MessageListener.
String	getMessageSelector() Gets this message consumer's message selector expression.
int	getPrefetchNumber()
protected long	getStartTime()
StatsImpl	getStats()
protected boolean	isBrowser() Retrive is a browser
boolean	isDurableSubscriber()
protected boolean	isNoLocal()
boolean	isTransientSubscriber()
protected void	processMessage(ActiveMQMessage message) Process a Message - passing either to the queue or 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.
protected void	setBrowser(boolean value) Set true if only a Browser
protected void	setConsumerName(String value) Set the name of the Consumer - used for durable subscribers
protected void	setConsumerNumber(int value) Set the locally unique consumer number
void	setMessageListener(MessageListener listener) Sets the message consumer's MessageListener.
void	setPrefetchNumber(int prefetchNumber)
int	size()
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 ActiveMQSession session

consumerIdentifier

protected String consumerIdentifier

messageQueue

protected MemoryBoundedQueue messageQueue

messageSelector

protected String messageSelector

consumerName

protected String consumerName

destination

protected ActiveMQDestination destination

consumerNumber

protected int consumerNumber

prefetchNumber

protected int prefetchNumber

startTime

protected long startTime

noLocal

protected boolean noLocal

browser

protected boolean browser

Constructor Detail

ActiveMQMessageConsumer

protected ActiveMQMessageConsumer(ActiveMQSession theSession,
                                  ActiveMQDestination dest,
                                  String name,
                                  String selector,
                                  int cnum,
                                  int prefetch,
                                  boolean noLocalValue,
                                  boolean browserValue)
                           throws JMSException

Create a MessageConsumer

Parameters:

theSession -

dest -

name -

selector -

cnum -

prefetch -

noLocalValue -

browserValue -

Throws:

JMSException

Method Detail

getLocalMemoryUsage

public long getLocalMemoryUsage()

Returns:

the memory used by the internal queue for this MessageConsumer

size

public int size()

Returns:

the number of messages enqueued by this consumer awaiting dispatch

getStats

public StatsImpl getStats()

Specified by:

getStats in interface StatsCapable

Returns:

Stats for this MessageConsumer

getConsumerStats

public JMSConsumerStatsImpl getConsumerStats()

Returns:

Stats for this MessageConsumer

toString

public String toString()

Overrides:

toString in class Object

Returns:

pretty print of this consumer

getPrefetchNumber

public int getPrefetchNumber()

Returns:

Returns the prefetchNumber.

setPrefetchNumber

public void setPrefetchNumber(int prefetchNumber)

Parameters:

prefetchNumber - The prefetchNumber to set.

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()

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)

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

Specified by:

close in interface Closeable

Throws:

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

isDurableSubscriber

public boolean isDurableSubscriber()

Returns:

true if this is a durable topic subscriber

isTransientSubscriber

public boolean isTransientSubscriber()

Returns:

true if this is a Transient Topic subscriber

checkClosed

protected void checkClosed()
                    throws IllegalStateException

Throws:

IllegalStateException

processMessage

protected void processMessage(ActiveMQMessage message)

Process a Message - passing either to the queue or message listener

Parameters:

message -

getConsumerIdentifier

protected String getConsumerIdentifier()

Returns:

Returns the consumerId.

getConsumerName

protected String getConsumerName()

Returns:

the consumer name - used for durable consumers

setConsumerName

protected void setConsumerName(String value)

Set the name of the Consumer - used for durable subscribers

Parameters:

value -

getConsumerNumber

protected int getConsumerNumber()

Returns:

the locally unique Consumer Number

setConsumerNumber

protected void setConsumerNumber(int value)

Set the locally unique consumer number

Parameters:

value -

isNoLocal

protected boolean isNoLocal()

Returns:

true if this consumer does not accept locally produced messages

isBrowser

protected boolean isBrowser()

Retrive is a browser

Returns:

true if a browser

setBrowser

protected void setBrowser(boolean value)

Set true if only a Browser

Parameters:

value -

See Also:

ActiveMQQueueBrowser

getDestination

protected ActiveMQDestination getDestination()

Returns:

ActiveMQDestination

getStartTime

protected long getStartTime()

Returns:

the startTime

clearMessagesInProgress

protected void clearMessagesInProgress()

start

public void start()

stop

public void stop()