TopicSubscriber.java

/*
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the License).  You may not use this file except in
 * compliance with the License.
 *
 * You can obtain a copy of the license at
 * https://glassfish.dev.java.net/public/CDDLv1.0.html or
 * glassfish/bootstrap/legal/CDDLv1.0.txt.
 * See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL
 * Header Notice in each file and include the License file
 * at glassfish/bootstrap/legal/CDDLv1.0.txt.
 * If applicable, add the following below the CDDL Header,
 * with the fields enclosed by brackets [] replaced by
 * you own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 */

package javax.jms;

/** A client uses a <CODE>TopicSubscriber</CODE> object to receive messages that
 * have been published to a topic. A <CODE>TopicSubscriber</CODE> object is the
 * publish/subscribe form of a message consumer. A <CODE>MessageConsumer</CODE>
 * can be created by using <CODE>Session.createConsumer</CODE>.
 *
 * <P>A <CODE>TopicSession</CODE> allows the creation of multiple
 * <CODE>TopicSubscriber</CODE> objects per topic.  It will deliver each
 * message for a topic to each
 * subscriber eligible to receive it. Each copy of the message
 * is treated as a completely separate message. Work done on one copy has
 * no effect on the others; acknowledging one does not acknowledge the
 * others; one message may be delivered immediately, while another waits
 * for its subscriber to process messages ahead of it.
 *
 * <P>Regular <CODE>TopicSubscriber</CODE> objects are not durable. They
 * receive only messages that are published while they are active.
 *
 * <P>Messages filtered out by a subscriber's message selector will never
 * be delivered to the subscriber. From the subscriber's perspective, they
 * do not exist.
 *
 * <P>In some cases, a connection may both publish and subscribe to a topic.
 * The subscriber <CODE>NoLocal</CODE> attribute allows a subscriber to inhibit
 * the
 * delivery of messages published by its own connection.
 *
 * <P>If a client needs to receive all the messages published on a topic,
 * including the ones published while the subscriber is inactive, it uses
 * a durable <CODE>TopicSubscriber</CODE>. The JMS provider retains a record of
 * this durable
 * subscription and insures that all messages from the topic's publishers
 * are retained until they are acknowledged by this durable
 * subscriber or they have expired.
 *
 * <P>Sessions with durable subscribers must always provide the same client
 * identifier. In addition, each client must specify a name that uniquely
 * identifies (within client identifier) each durable subscription it creates.
 * Only one session at a time can have a <CODE>TopicSubscriber</CODE> for a
 * particular durable subscription.
 *
 * <P>A client can change an existing durable subscription by creating a
 * durable <CODE>TopicSubscriber</CODE> with the same name and a new topic
 * and/or message
 * selector. Changing a durable subscription is equivalent to unsubscribing
 * (deleting) the old one and creating a new one.
 *
 * <P>The <CODE>unsubscribe</CODE> method is used to delete a durable
 * subscription. The <CODE>unsubscribe</CODE> method can be used at the
 * <CODE>Session</CODE> or <CODE>TopicSession</CODE> level.
 * This method deletes the state being
 * maintained on behalf of the subscriber by its provider.
 *
 * <P>Creating a <CODE>MessageConsumer</CODE> provides the same features as
 * creating a <CODE>TopicSubscriber</CODE>. To create a durable subscriber,
 * use of <CODE>Session.CreateDurableSubscriber</CODE> is recommended. The
 * <CODE>TopicSubscriber</CODE> is provided to support existing code.
 *
 *
 * @version     1.1 - February 2, 2002
 * @author      Mark Hapner
 * @author      Rich Burridge
 * @author      Kate Stout
 *
 * @see         javax.jms.Session#createConsumer
 * @see         javax.jms.Session#createDurableSubscriber
 * @see         javax.jms.TopicSession
 * @see         javax.jms.TopicSession#createSubscriber
 * @see         javax.jms.MessageConsumer
 */

public interface TopicSubscriber extends MessageConsumer
{

  /** Gets the <CODE>Topic</CODE> associated with this subscriber.
    *
    * @return this subscriber's <CODE>Topic</CODE>
    *
    * @exception JMSException if the JMS provider fails to get the topic for
    *                         this topic subscriber
    *                         due to some internal error.
    */

  Topic getTopic() throws JMSException;

  /** Gets the <CODE>NoLocal</CODE> attribute for this subscriber.
    * The default value for this attribute is false.
    *
    * @return true if locally published messages are being inhibited
    *
    * @exception JMSException if the JMS provider fails to get the
    *                         <CODE>NoLocal</CODE> attribute for
    *                         this topic subscriber
    *                         due to some internal error.
    */

  boolean getNoLocal() throws JMSException;
}