Module jakarta.messaging

Package jakarta.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

Since:

JMS 1.0

Version:

Jakarta Messaging 2.0

See Also:

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

Field Summary

Fields inherited from interface jakarta.jms.Session

AUTO_ACKNOWLEDGE, CLIENT_ACKNOWLEDGE, DUPS_OK_ACKNOWLEDGE, SESSION_TRANSACTED

Method Summary

Modifier and Type	Method	Description
TopicSubscriber	createDurableSubscriber(Topic topic, String name)	Creates an unshared durable subscription on the specified topic (if one does not already exist) and creates a consumer on that durable subscription.
TopicSubscriber	createDurableSubscriber(Topic topic, String name, String messageSelector, boolean noLocal)	Creates an unshared durable subscription on the specified topic (if one does not already exist), specifying a message selector and the noLocal parameter, and creates a consumer on that 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 jakarta.jms.Session

close, commit, createBrowser, createBrowser, createBytesMessage, createConsumer, createConsumer, createConsumer, createDurableConsumer, createDurableConsumer, createMapMessage, createMessage, createObjectMessage, createObjectMessage, createProducer, createQueue, createSharedConsumer, createSharedConsumer, createSharedDurableConsumer, createSharedDurableConsumer, 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 Jakarta Messaging 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

Returns:

A nondurable subscriber to the specified topic.

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

Returns:

A nondurable subscriber to the specified topic.

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 an unshared durable subscription on the specified topic (if one does not already exist) and creates a consumer on that durable subscription. This method creates the durable subscription without a message selector and with a noLocal value of false.

A durable subscription is used by an application which needs to receive all the messages published on a topic, including the ones published when there is no active consumer associated with it. The Jakarta Messaging 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.

This method may only be used with non-shared durable subscriptions. Any durable subscription created using this method will be non-shared. This means that only one active (i.e. not closed) consumer on the subscription may exist at a time. The term "consumer" here means a TopicSubscriber, MessageConsumer or JMSConsumer object in any client.

An unshared durable subscription is identified by a name specified by the client and by the client identifier, which must be set. An application which subsequently wishes to create a consumer on that non-shared durable subscription must use the same client identifier.

If an unshared durable subscription already exists with the same name and client identifier and the same topic and message selector, and there is no consumer already active (i.e. not closed) 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, then this method creates a TopicSubscriber on the existing durable subscription.

If an unshared durable subscription already exists with the same name and client identifier, and there is a consumer already active (i.e. not closed) on the durable subscription, or consumed messages from that subscription are still part of a pending transaction or are not yet acknowledged in the session, then a JMSException will be thrown.

If an unshared durable subscription already exists with the same name and client identifier but a different topic, message selector or noLocal value has been specified, and there is no consumer already active (i.e. not closed) 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, then the durable subscription will be deleted and a new one created.

A shared durable subscription and an unshared durable subscription may not have the same name and client identifier. If a shared durable subscription already exists with the same name and client identifier then a JMSException is thrown.

There is no restriction on durable subscriptions and shared non-durable subscriptions having the same name and clientId. Such subscriptions would be completely separate.

This method is identical to the corresponding createDurableConsumer method except that it returns a TopicSubscriber rather than a MessageConsumer to represent the consumer.

Specified by:

createDurableSubscriber in interface Session

Parameters:

topic - the non-temporary Topic to subscribe to

name - the name used to identify this subscription

Returns:

An unshared durable subscription on the specified topic.

Throws:

InvalidDestinationException - if an invalid topic is specified.

JMSException -

• if the session fails to create the non-shared durable subscription and TopicSubscriber due to some internal error
• if the client identifier is unset
• if an unshared durable subscription already exists with the same name and client identifier, and there is a consumer already active
• if a shared durable subscription already exists with the same name and client identifier

createDurableSubscriber

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

Creates an unshared durable subscription on the specified topic (if one does not already exist), specifying a message selector and the noLocal parameter, and creates a consumer on that durable subscription.

A durable subscription is used by an application which needs to receive all the messages published on a topic, including the ones published when there is no active consumer associated with it. The Jakarta Messaging 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.

This method may only be used with non-shared durable subscriptions. Any durable subscription created using this method will be non-shared. This means that only one active (i.e. not closed) consumer on the subscription may exist at a time. The term "consumer" here means a TopicSubscriber, MessageConsumer or JMSConsumer object in any client.

An unshared durable subscription is identified by a name specified by the client and by the client identifier, which must be set. An application which subsequently wishes to create a consumer on that non-shared durable subscription must use the same client identifier.

If an unshared durable subscription already exists with the same name and client identifier and the same topic and message selector, and there is no consumer already active (i.e. not closed) 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, then this method creates a TopicSubscriber on the existing durable subscription.

If an unshared durable subscription already exists with the same name and client identifier, and there is a consumer already active (i.e. not closed) on the durable subscription, or consumed messages from that subscription are still part of a pending transaction or are not yet acknowledged in the session, then a JMSException will be thrown.

If an unshared durable subscription already exists with the same name and client identifier but a different topic, message selector or noLocal value has been specified, and there is no consumer already active (i.e. not closed) 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, then the durable subscription will be deleted and a new one created.

A shared durable subscription and an unshared durable subscription may not have the same name and client identifier. If a shared durable subscription already exists with the same name and client identifier then a JMSException is thrown.

If noLocal is set to true then any messages published to the topic using this session's connection, or any other connection with the same client identifier, will not be added to the durable subscription.

There is no restriction on durable subscriptions and shared non-durable subscriptions having the same name and clientId. Such subscriptions would be completely separate.

This method is identical to the corresponding createDurableConsumer method except that it returns a TopicSubscriber rather than a MessageConsumer to represent the consumer.

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 then any messages published to the topic using this session's connection, or any other connection with the same client identifier, will not be added to the durable subscription.

Returns:

An unshared durable subscription on the specified topic.

Throws:

InvalidDestinationException - if an invalid topic is specified.

InvalidSelectorException - if the message selector is invalid.

JMSException -

• if the session fails to create the non-shared durable subscription and TopicSubscriber due to some internal error
• if the client identifier is unset
• if an unshared durable subscription already exists with the same name and client identifier, and there is a consumer already active
• if a shared durable subscription already exists with the same name and client identifier

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

Returns:

A publisher for the specified topic.

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.