javax.jms.MessageConsumer Maven / Gradle / Ivy
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package javax.jms;
/** 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 MessageConsumer 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 MessageConsumer's
* messages or have the MessageConsumer asynchronously deliver them
* as they arrive.
*
* For synchronous receipt, a client can request the next message from a
* MessageConsumer 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 MessageConsumer.
* As messages arrive at the MessageConsumer, it delivers them by calling
* the MessageListener's onMessage method.
*
* It is a client programming error for a MessageListener to throw an exception.
*
* @version 2.0
*
* @see javax.jms.QueueReceiver
* @see javax.jms.TopicSubscriber
* @see javax.jms.Session
*/
public interface MessageConsumer {
/** Gets this message consumer's message selector expression.
*
* @return 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)
*
* @exception JMSException if the JMS provider fails to get the message
* selector due to some internal error.
*/
String
getMessageSelector() throws JMSException;
/** Gets the MessageConsumer's MessageListener.
*
* This method must not be used in a Java EE web or EJB application.
* Doing so may cause a JMSException to be thrown though this is not guaranteed.
*
* @return the MessageConsumer's MessageListener, or null if one was not set
*
* @exception JMSException if the JMS provider fails to get the MessageListener
* for one of the following reasons:
*
* - an internal error has occurred or
*
- this method has been called in a Java EE web or EJB application
* (though it is not guaranteed that an exception is thrown in this case)
*
*
* @see javax.jms.MessageConsumer#setMessageListener(javax.jms.MessageListener)
*/
MessageListener getMessageListener() throws JMSException;
/** Sets the MessageConsumer's MessageListener.
*
* Setting the the MessageListener to null is the equivalent of
* unsetting the MessageListener for the MessageConsumer.
*
* The effect of calling this method
* while messages are being consumed by an existing listener
* or the MessageConsumer is being used to consume messages synchronously
* is undefined.
*
* This method must not be used in a Java EE web or EJB application.
* Doing so may cause a JMSException to be thrown though this is not guaranteed.
*
* @param listener the listener to which the messages are to be
* delivered
*
* @exception JMSException if the JMS provider fails to set the MessageConsumer's MessageListener
* for one of the following reasons:
*
* - an internal error has occurred or
*
- this method has been called in a Java EE web or EJB application
* (though it is not guaranteed that an exception is thrown in this case)
*
*
* @see javax.jms.MessageConsumer#getMessageListener()
*/
void setMessageListener(MessageListener listener) 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.
*
* @return the next message produced for this message consumer, or
* null if this message consumer is concurrently closed
*
* @exception JMSException if the JMS provider fails to receive the next
* message due to some internal error.
*
*/
Message
receive() 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.
*
* @param timeout the timeout value (in milliseconds)
*
* @return the next message produced for this message consumer, or
* null if the timeout expires or this message consumer is concurrently
* closed
*
* @exception JMSException if the JMS provider fails to receive the next
* message due to some internal error.
*/
Message
receive(long timeout) throws JMSException;
/** Receives the next message if one is immediately available.
*
* @return the next message produced for this message consumer, or
* null if one is not available
*
* @exception JMSException if the JMS provider fails to receive the next
* message due to some internal error.
*/
Message
receiveNoWait() 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.
*
* @exception JMSException if the JMS provider fails to close the consumer
* due to some internal error.
*/
void
close() throws JMSException;
}