- /*
- * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
-
- package javax.jms;
-
- /** A client uses a <CODE>MessageConsumer</CODE> object to receive messages
- * from a destination. A <CODE>MessageConsumer</CODE> object is created by
- * passing a <CODE>Destination</CODE> object to a message-consumer creation
- * method supplied by a session.
- *
- * <P><CODE>MessageConsumer</CODE> is the parent interface for all message
- * consumers.
- *
- * <P>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.
- *
- * <P>A client may either synchronously receive a message consumer's messages
- * or have the consumer asynchronously deliver them as they arrive.
- *
- * <P>For synchronous receipt, a client can request the next message from a
- * message consumer using one of its <CODE>receive</CODE> methods. There are
- * several variations of <CODE>receive</CODE> that allow a
- * client to poll or wait for the next message.
- *
- * <P>For asynchronous delivery, a client can register a
- * <CODE>MessageListener</CODE> object with a message consumer.
- * As messages arrive at the message consumer, it delivers them by calling the
- * <CODE>MessageListener</CODE>'s <CODE>onMessage</CODE> method.
- *
- * <P>It is a client programming error for a <CODE>MessageListener</CODE> to
- * throw an exception.
- *
- * @version 1.0 - 13 March 1998
- * @author Mark Hapner
- * @author Rich Burridge
- *
- * @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 message consumer's <CODE>MessageListener</CODE>.
- *
- * @return the listener for the message consumer, or null if no listener
- * is set
- *
- * @exception JMSException if the JMS provider fails to get the message
- * listener due to some internal error.
- * @see javax.jms.MessageConsumer#setMessageListener
- */
-
- MessageListener
- getMessageListener() throws JMSException;
-
-
- /** Sets the message consumer's <CODE>MessageListener</CODE>.
- *
- * <P>Setting the message listener to null is the equivalent of
- * unsetting the message listener for the message consumer.
- *
- * <P>The effect of calling <CODE>MessageConsumer.setMessageListener</CODE>
- * while messages are being consumed by an existing listener
- * or the consumer is being used to consume messages synchronously
- * is undefined.
- *
- * @param listener the listener to which the messages are to be
- * delivered
- *
- * @exception JMSException if the JMS provider fails to set the message
- * listener due to some internal error.
- * @see javax.jms.MessageConsumer#getMessageListener
- */
-
- void
- setMessageListener(MessageListener listener) throws JMSException;
-
-
- /** Receives the next message produced for this message consumer.
- *
- * <P>This call blocks indefinitely until a message is produced
- * or until this message consumer is closed.
- *
- * <P>If this <CODE>receive</CODE> 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.
- *
- * <P>This call blocks until a message arrives, the
- * timeout expires, or this message consumer is closed.
- * A <CODE>timeout</CODE> 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.
- *
- * <P>Since a provider may allocate some resources on behalf of a
- * <CODE>MessageConsumer</CODE> 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>This call blocks until a <CODE>receive</CODE> or message listener in
- * progress has completed. A blocked message consumer <CODE>receive</CODE>
- * 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;
- }