javax.jms

Interface TopicSession

All Superinterfaces:

AutoCloseable, Runnable, Session

public interface TopicSession
extends Session

A TopicSession object provides methods for creating TopicPublisher, TopicSubscriber, and TemporaryTopic objects. It also provides a method for deleting its client's durable subscribers.

A TopicSession is used for creating Pub/Sub specific objects. In general, use the Session object, and use TopicSession only to support existing code. Using the Session object simplifies the programming model, and allows transactions to be used across the two messaging domains.

A TopicSession cannot be used to create objects specific to the point-to-point domain. The following methods inherit from Session, but must throw an IllegalStateException if used from TopicSession:

• createBrowser
• createQueue
• createTemporaryQueue

Version:

1.1 - April 9, 2002

Author:

Mark Hapner, Rich Burridge, Kate Stout

See Also:

Session, Connection.createSession(boolean, int), TopicConnection.createTopicSession(boolean, int), XATopicSession.getTopicSession()

Field Summary

Fields inherited from interface javax.jms.Session

AUTO_ACKNOWLEDGE, CLIENT_ACKNOWLEDGE, DUPS_OK_ACKNOWLEDGE, SESSION_TRANSACTED

Method Summary

Methods

Modifier and Type	Method and Description
TopicSubscriber	createDurableSubscriber(Topic topic, String name) Creates a durable subscription with the specified name on the specified topic, and creates a TopicSubscriber on that durable subscription.
TopicSubscriber	createDurableSubscriber(Topic topic, String name, String messageSelector, boolean noLocal) Creates a durable subscription with the specified name on the specified topic (if one does not already exist), and creates a TopicSubscriber on that durable subscription, specifying a message selector and whether messages published by its own connection should be added to the durable subscription.
TopicPublisher	createPublisher(Topic topic) Creates a publisher for the specified topic.
TopicSubscriber	createSubscriber(Topic topic) Creates a nondurable subscriber to the specified topic.
TopicSubscriber	createSubscriber(Topic topic, String messageSelector, boolean noLocal) Creates a nondurable subscriber to the specified topic, using a message selector or specifying whether messages published by its own connection should be delivered to it.
TemporaryTopic	createTemporaryTopic() Creates a TemporaryTopic object.
Topic	createTopic(String topicName) Creates a topic identity given a Topic name.
void	unsubscribe(String name) Unsubscribes a durable subscription that has been created by a client.

Methods inherited from interface javax.jms.Session

close, commit, createBrowser, createBrowser, createBytesMessage, createConsumer, createConsumer, createConsumer, createDurableConsumer, createDurableConsumer, createMapMessage, createMessage, createObjectMessage, createObjectMessage, createProducer, createQueue, createSharedConsumer, createSharedConsumer, createSharedConsumer, createStreamMessage, createTemporaryQueue, createTextMessage, createTextMessage, getAcknowledgeMode, getMessageListener, getTransacted, recover, rollback, run, setMessageListener

Method Detail

createTopic

Topic createTopic(String topicName)
                  throws JMSException

Creates a topic identity given a Topic name.

This facility is provided for the rare cases where clients need to dynamically manipulate topic identity. This allows the creation of a topic identity with a provider-specific name. Clients that depend on this ability are not portable.

Note that this method is not for creating the physical topic. The physical creation of topics is an administrative task and is not to be initiated by the JMS API. The one exception is the creation of temporary topics, which is accomplished with the createTemporaryTopic method.

Specified by:

createTopic in interface Session

Parameters:

topicName - the name of this Topic

Returns:

a Topic with the given name

Throws:

JMSException - if the session fails to create a topic due to some internal error.

createSubscriber

TopicSubscriber createSubscriber(Topic topic)
                                 throws JMSException

Creates a nondurable subscriber to the specified topic.

A client uses a TopicSubscriber object to receive messages that have been published to a topic.

Regular TopicSubscriber objects are not durable. They receive only messages that are published while they are active.

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. The default value for this attribute is false.

Parameters:

topic - the Topic to subscribe to

Throws:

JMSException - if the session fails to create a subscriber due to some internal error.

InvalidDestinationException - if an invalid topic is specified.

createSubscriber

TopicSubscriber createSubscriber(Topic topic,
                               String messageSelector,
                               boolean noLocal)
                                 throws JMSException

Creates a nondurable subscriber to the specified topic, using a message selector or specifying whether messages published by its own connection should be delivered to it.

A client uses a TopicSubscriber object to receive messages that have been published to a topic.

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. The default value for this attribute is false.

Parameters:

topic - the Topic to subscribe to

messageSelector - only messages with properties matching the message selector expression are delivered. A value of null or an empty string indicates that there is no message selector for the message consumer.

noLocal - if set, inhibits the delivery of messages published by its own connection

Throws:

JMSException - if the session fails to create a subscriber due to some internal error.

InvalidDestinationException - if an invalid topic is specified.

InvalidSelectorException - if the message selector is invalid.

createDurableSubscriber

TopicSubscriber createDurableSubscriber(Topic topic,
                                      String name)
                                        throws JMSException

Creates a durable subscription with the specified name on the specified topic, and creates a TopicSubscriber on that durable subscription.

This method is identical to the corresponding createDurableConsumer method except that it returns a TopicSubscriber rather than a MessageConsumer. The term "consumer" applies to both TopicSubscriber and MessageConsumer objects.

If a durable subscription already exists with the same name and client identifier (if set) and the same topic and message selector then this method creates a TopicSubscriber on the existing durable subscription.

A durable subscription is used by a client which needs to receive all the messages published on a topic, including the ones published when there is no consumer associated with it. The JMS provider retains a record of this durable subscription and ensures that all messages from the topic's publishers are retained until they are delivered to, and acknowledged by, a consumer on this durable subscription or until they have expired.

A durable subscription will continue to accumulate messages until it is deleted using the unsubscribe method.

A consumer may be created on a durable subscription using the createDurableConsumer methods on JMSContext, or the createDurableConsumer and createDurableSubscriber methods on Session or TopicSession. A durable subscription which has a consumer associated with it is described as being active. A durable subscription which has no consumer associated with it is described as being inactive.

A durable subscription may have more than one active consumer (this was not permitted prior to JMS 2.0). Each message from the subscription will be delivered to only one of the consumers on that subscription.

A durable subscription is identified by a name specified by the client and by the client identifier if set. If the client identifier was set when the durable subscription was first created then a client which subsequently wishes to create a consumer on that durable subscription must use the same client identifier.

If there are no active consumers on the durable subscription (and no consumed messages from that subscription are still part of a pending transaction or are not yet acknowledged in the session), and this method is used to create a new consumer on that durable subscription, specifying the same name and client identifier (if set) but a different topic or message selector, then the durable subscription will be deleted and a new one created. However if there is an active consumer on the durable subscription (or a consumed message from that subscription is still part of a pending transaction or is not yet acknowledged in the session), and an attempt is made to create an additional consumer, specifying the same name and client identifier (if set) but a different topic or message selector, then a JMSException will be thrown.

Specified by:

createDurableSubscriber in interface Session

Parameters:

topic - the non-temporary Topic to subscribe to

name - the name used to identify this subscription

Throws:

JMSException - if the session fails to create the durable subscription and TopicSubscriber due to some internal error.

InvalidDestinationException - if an invalid topic is specified.

createDurableSubscriber

TopicSubscriber createDurableSubscriber(Topic topic,
                                      String name,
                                      String messageSelector,
                                      boolean noLocal)
                                        throws JMSException

Creates a durable subscription with the specified name on the specified topic (if one does not already exist), and creates a TopicSubscriber on that durable subscription, specifying a message selector and whether messages published by its own connection should be added to the durable subscription.

This method is identical to the corresponding createDurableConsumer method except that it returns a TopicSubscriber rather than a MessageConsumer. The term "consumer" applies to both TopicSubscriber and MessageConsumer objects.

If a durable subscription already exists with the same name and client identifier (if set) and the same topic and message selector then this method creates a TopicSubscriber on the existing durable subscription.

A durable subscription is used by a client which needs to receive all the messages published on a topic, including the ones published when there is no consumer associated with it. The JMS provider retains a record of this durable subscription and ensures that all messages from the topic's publishers are retained until they are delivered to, and acknowledged by, a consumer on this durable subscription or until they have expired.

A durable subscription will continue to accumulate messages until it is deleted using the unsubscribe method.

A consumer may be created on a durable subscription using the createDurableConsumer methods on JMSContext, or the createDurableConsumer and createDurableSubscriber methods on Session or TopicSession. A durable subscription which has a consumer associated with it is described as being active. A durable subscription which has no consumer associated with it is described as being inactive.

A durable subscription may have more than one active consumer (this was not permitted prior to JMS 2.0). Each message from the subscription will be delivered to only one of the consumers on that subscription.

A durable subscription is identified by a name specified by the client and by the client identifier if set. If the client identifier was set when the durable subscription was first created then a client which subsequently wishes to create a consumer on that durable subscription must use the same client identifier.

If there are no active consumers on the durable subscription (and no consumed messages from that subscription are still part of a pending transaction or are not yet acknowledged in the session), and this method is used to create a new consumer on that durable subscription, specifying the same name and client identifier (if set) but a different topic or message selector, then the durable subscription will be deleted and a new one created. However if there is an active consumer on the durable subscription (or a consumed message from that subscription is still part of a pending transaction or is not yet acknowledged in the session), and an attempt is made to create an additional consumer, specifying the same name and client identifier (if set) but a different topic or message selector, then a JMSException will be thrown.

The NoLocal argument is for use when the session's connection is also being used to publish messages to the topic. If NoLocal is set to true then messages published to the topic by its own connection will not be added to the durable subscription. The default value of this argument is false.

Specified by:

createDurableSubscriber in interface Session

Parameters:

topic - the non-temporary Topic to subscribe to

name - the name used to identify this subscription

messageSelector - only messages with properties matching the message selector expression are added to the durable subscription. A value of null or an empty string indicates that there is no message selector for the durable subscription.

noLocal - if true, messages published by its own connection will not be added to the durable subscription.

Throws:

JMSException - if the session fails to create the durable subscription and TopicSubscriber due to some internal error.

InvalidDestinationException - if an invalid topic is specified.

InvalidSelectorException - if the message selector is invalid.

createPublisher

TopicPublisher createPublisher(Topic topic)
                               throws JMSException

Creates a publisher for the specified topic.

A client uses a TopicPublisher object to publish messages on a topic. Each time a client creates a TopicPublisher on a topic, it defines a new sequence of messages that have no ordering relationship with the messages it has previously sent.

Parameters:

topic - the Topic to publish to, or null if this is an unidentified producer

Throws:

JMSException - if the session fails to create a publisher due to some internal error.

InvalidDestinationException - if an invalid topic is specified.

createTemporaryTopic

TemporaryTopic createTemporaryTopic()
                                    throws JMSException

Creates a TemporaryTopic object. Its lifetime will be that of the TopicConnection unless it is deleted earlier.

Specified by:

createTemporaryTopic in interface Session

Returns:

a temporary topic identity

Throws:

JMSException - if the session fails to create a temporary topic due to some internal error.

unsubscribe

void unsubscribe(String name)
                 throws JMSException

Unsubscribes a durable subscription that has been created by a client.

This method deletes the state being maintained on behalf of the subscriber by its provider.

It is erroneous for a client to delete a durable subscription while there is an active TopicSubscriber for the subscription, or while a consumed message is part of a pending transaction or has not been acknowledged in the session.

Specified by:

unsubscribe in interface Session

Parameters:

name - the name used to identify this subscription

Throws:

JMSException - if the session fails to unsubscribe to the durable subscription due to some internal error.

InvalidDestinationException - if an invalid subscription name is specified.