org.apache.activemq.ActiveMQTopicSubscriber Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq;
import javax.jms.JMSException;
import javax.jms.Topic;
import javax.jms.TopicSubscriber;
import org.apache.activemq.command.ActiveMQDestination;
import org.apache.activemq.command.ConsumerId;
/**
* A client uses a TopicSubscriber object to receive messages
* that have been published to a topic. A TopicSubscriber object
* is the publish/subscribe form of a message consumer. A
* MessageConsumer can be created by using
* Session.createConsumer.
*
*
* A TopicSession allows the creation of multiple
* TopicSubscriber 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.
*
*
* Regular TopicSubscriber objects are not durable. They receive
* only messages that are published while they are active.
*
*
* 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.
*
*
* In some cases, a connection may both publish and subscribe to a topic. The
* subscriber NoLocal attribute allows a subscriber to inhibit
* the delivery of messages published by its own connection.
*
*
* 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 TopicSubscriber. 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.
*
*
* 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 TopicSubscriber for a
* particular durable subscription.
*
*
* A client can change an existing durable subscription by creating a durable
* TopicSubscriber 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.
*
*
* The unsubscribe method is used to delete a durable
* subscription. The unsubscribe method can be used at the
* Session or TopicSession level. This method
* deletes the state being maintained on behalf of the subscriber by its
* provider.
*
*
* Creating a MessageConsumer provides the same features as
* creating a TopicSubscriber. To create a durable subscriber,
* use of Session.CreateDurableSubscriber is recommended. The
* TopicSubscriber is provided to support existing code.
*
* @see javax.jms.Session#createConsumer
* @see javax.jms.Session#createDurableSubscriber
* @see javax.jms.TopicSession
* @see javax.jms.TopicSession#createSubscriber
* @see javax.jms.TopicSubscriber
* @see javax.jms.MessageConsumer
*/
public class ActiveMQTopicSubscriber extends ActiveMQMessageConsumer implements
TopicSubscriber {
/**
* @param theSession
* @param value
* @param dest
* @param name
* @param selector
* @param cnum
* @param noLocalValue
* @param browserValue
* @param asyncDispatch
* @throws JMSException
*/
protected ActiveMQTopicSubscriber(ActiveMQSession theSession,
ConsumerId consumerId, ActiveMQDestination dest, String name, String selector, int prefetch, int maximumPendingMessageCount,
boolean noLocalValue, boolean browserValue, boolean asyncDispatch) throws JMSException {
super(theSession, consumerId, dest, name, selector, prefetch, maximumPendingMessageCount, noLocalValue, browserValue, asyncDispatch, null);
}
/**
* Gets the Topic associated with this subscriber.
*
* @return this subscriber's Topic
* @throws JMSException if the JMS provider fails to get the topic for this topic
* subscriber due to some internal error.
*/
public Topic getTopic() throws JMSException {
checkClosed();
return (Topic) super.getDestination();
}
/**
* Gets the NoLocal attribute for this subscriber. The
* default value for this attribute is false.
*
* @return true if locally published messages are being inhibited
* @throws JMSException if the JMS provider fails to get the NoLocal
* attribute for this topic subscriber due to some
* internal error.
*/
public boolean getNoLocal() throws JMSException {
checkClosed();
return super.isNoLocal();
}
}