Interface Session
-
- All Superinterfaces:
java.lang.Runnable
- All Known Subinterfaces:
QueueSession
,TopicSession
,XAQueueSession
,XASession
,XATopicSession
public interface Session extends java.lang.Runnable
A
Session
object is a single-threaded context for producing and consuming messages. Although it may allocate provider resources outside the Java virtual machine (JVM), it is considered a lightweight JMS object.A session serves several purposes:
- It is a factory for its message producers and consumers.
- It supplies provider-optimized message factories.
- It is a factory for
TemporaryTopics
andTemporaryQueues
. - It provides a way to create
Queue
orTopic
objects for those clients that need to dynamically manipulate provider-specific destination names. - It supports a single series of transactions that combine work spanning its producers and consumers into atomic units.
- It defines a serial order for the messages it consumes and the messages it produces.
- It retains messages it consumes until they have been acknowledged.
- It serializes execution of message listeners registered with its message consumers.
- It is a factory for
QueueBrowsers
.
A session can create and service multiple message producers and consumers.
One typical use is to have a thread block on a synchronous
MessageConsumer
until a message arrives. The thread may then use one or more of theSession
'sMessageProducer
s.If a client desires to have one thread produce messages while others consume them, the client should use a separate session for its producing thread.
Once a connection has been started, any session with one or more registered message listeners is dedicated to the thread of control that delivers messages to it. It is erroneous for client code to use this session or any of its constituent objects from another thread of control. The only exception to this rule is the use of the session or connection
close
method.It should be easy for most clients to partition their work naturally into sessions. This model allows clients to start simply and incrementally add message processing complexity as their need for concurrency grows.
The
close
method is the only session method that can be called while some other session method is being executed in another thread.A session may be specified as transacted. Each transacted session supports a single series of transactions. Each transaction groups a set of message sends and a set of message receives into an atomic unit of work. In effect, transactions organize a session's input message stream and output message stream into series of atomic units. When a transaction commits, its atomic unit of input is acknowledged and its associated atomic unit of output is sent. If a transaction rollback is done, the transaction's sent messages are destroyed and the session's input is automatically recovered.
The content of a transaction's input and output units is simply those messages that have been produced and consumed within the session's current transaction.
A transaction is completed using either its session's
commit
method or its session'srollback
method. The completion of a session's current transaction automatically begins the next. The result is that a transacted session always has a current transaction within which its work is done.The Java Transaction Service (JTS) or some other transaction monitor may be used to combine a session's transaction with transactions on other resources (databases, other JMS sessions, etc.). Since Java distributed transactions are controlled via the Java Transaction API (JTA), use of the session's
commit
androllback
methods in this context is prohibited.The JMS API does not require support for JTA; however, it does define how a provider supplies this support.
Although it is also possible for a JMS client to handle distributed transactions directly, it is unlikely that many JMS clients will do this. Support for JTA in the JMS API is targeted at systems vendors who will be integrating the JMS API into their application server products.
- See Also:
QueueSession
,TopicSession
,XASession
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Field Summary
Fields Modifier and Type Field Description static int
AUTO_ACKNOWLEDGE
With this acknowledgment mode, the session automatically acknowledges a client's receipt of a message either when the session has successfully returned from a call toreceive
or when the message listener the session has called to process the message successfully returns.static int
CLIENT_ACKNOWLEDGE
With this acknowledgment mode, the client acknowledges a consumed message by calling the message'sacknowledge
method.static int
DUPS_OK_ACKNOWLEDGE
This acknowledgment mode instructs the session to lazily acknowledge the delivery of messages.static int
SESSION_TRANSACTED
This value is returned from the methodgetAcknowledgeMode
if the session is transacted.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
close()
Closes the session.void
commit()
Commits all messages done in this transaction and releases any locks currently held.QueueBrowser
createBrowser(Queue queue)
Creates aQueueBrowser
object to peek at the messages on the specified queue.QueueBrowser
createBrowser(Queue queue, java.lang.String messageSelector)
Creates aQueueBrowser
object to peek at the messages on the specified queue using a message selector.BytesMessage
createBytesMessage()
Creates aBytesMessage
object.MessageConsumer
createConsumer(Destination destination)
Creates aMessageConsumer
for the specified destination.MessageConsumer
createConsumer(Destination destination, java.lang.String messageSelector)
Creates aMessageConsumer
for the specified destination, using a message selector.MessageConsumer
createConsumer(Destination destination, java.lang.String messageSelector, boolean NoLocal)
CreatesMessageConsumer
for the specified destination, using a message selector.TopicSubscriber
createDurableSubscriber(Topic topic, java.lang.String name)
Creates a durable subscriber to the specified topic.TopicSubscriber
createDurableSubscriber(Topic topic, java.lang.String name, java.lang.String messageSelector, boolean noLocal)
Creates a durable subscriber to the specified topic, using a message selector and specifying whether messages published by its own connection should be delivered to it.MapMessage
createMapMessage()
Creates aMapMessage
object.Message
createMessage()
Creates aMessage
object.ObjectMessage
createObjectMessage()
Creates anObjectMessage
object.ObjectMessage
createObjectMessage(java.io.Serializable object)
Creates an initializedObjectMessage
object.MessageProducer
createProducer(Destination destination)
Creates aMessageProducer
to send messages to the specified destination.Queue
createQueue(java.lang.String queueName)
Creates a queue identity given aQueue
name.StreamMessage
createStreamMessage()
Creates aStreamMessage
object.TemporaryQueue
createTemporaryQueue()
Creates aTemporaryQueue
object.TemporaryTopic
createTemporaryTopic()
Creates aTemporaryTopic
object.TextMessage
createTextMessage()
Creates aTextMessage
object.TextMessage
createTextMessage(java.lang.String text)
Creates an initializedTextMessage
object.Topic
createTopic(java.lang.String topicName)
Creates a topic identity given aTopic
name.int
getAcknowledgeMode()
Returns the acknowledgement mode of the session.MessageListener
getMessageListener()
Returns the session's distinguished message listener (optional).boolean
getTransacted()
Indicates whether the session is in transacted mode.void
recover()
Stops message delivery in this session, and restarts message delivery with the oldest unacknowledged message.void
rollback()
Rolls back any messages done in this transaction and releases any locks currently held.void
run()
Optional operation, intended to be used only by Application Servers, not by ordinary JMS clients.void
setMessageListener(MessageListener listener)
Sets the session's distinguished message listener (optional).void
unsubscribe(java.lang.String name)
Unsubscribes a durable subscription that has been created by a client.
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Field Detail
-
AUTO_ACKNOWLEDGE
static final int AUTO_ACKNOWLEDGE
With this acknowledgment mode, the session automatically acknowledges a client's receipt of a message either when the session has successfully returned from a call toreceive
or when the message listener the session has called to process the message successfully returns.- See Also:
- Constant Field Values
-
CLIENT_ACKNOWLEDGE
static final int CLIENT_ACKNOWLEDGE
With this acknowledgment mode, the client acknowledges a consumed message by calling the message'sacknowledge
method. Acknowledging a consumed message acknowledges all messages that the session has consumed.When client acknowledgment mode is used, a client may build up a large number of unacknowledged messages while attempting to process them. A JMS provider should provide administrators with a way to limit client overrun so that clients are not driven to resource exhaustion and ensuing failure when some resource they are using is temporarily blocked.
- See Also:
Message.acknowledge()
, Constant Field Values
-
DUPS_OK_ACKNOWLEDGE
static final int DUPS_OK_ACKNOWLEDGE
This acknowledgment mode instructs the session to lazily acknowledge the delivery of messages. This is likely to result in the delivery of some duplicate messages if the JMS provider fails, so it should only be used by consumers that can tolerate duplicate messages. Use of this mode can reduce session overhead by minimizing the work the session does to prevent duplicates.- See Also:
- Constant Field Values
-
SESSION_TRANSACTED
static final int SESSION_TRANSACTED
This value is returned from the methodgetAcknowledgeMode
if the session is transacted. If aSession
is transacted, the acknowledgement mode is ignored.- See Also:
- Constant Field Values
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Method Detail
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createBytesMessage
BytesMessage createBytesMessage() throws JMSException
Creates aBytesMessage
object. ABytesMessage
object is used to send a message containing a stream of uninterpreted bytes.- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
-
createMapMessage
MapMessage createMapMessage() throws JMSException
Creates aMapMessage
object. AMapMessage
object is used to send a self-defining set of name-value pairs, where names areString
objects and values are primitive values in the Java programming language.- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
-
createMessage
Message createMessage() throws JMSException
Creates aMessage
object. TheMessage
interface is the root interface of all JMS messages. AMessage
object holds all the standard message header information. It can be sent when a message containing only header information is sufficient.- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
-
createObjectMessage
ObjectMessage createObjectMessage() throws JMSException
Creates anObjectMessage
object. AnObjectMessage
object is used to send a message that contains a serializable Java object.- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
-
createObjectMessage
ObjectMessage createObjectMessage(java.io.Serializable object) throws JMSException
Creates an initializedObjectMessage
object. AnObjectMessage
object is used to send a message that contains a serializable Java object.- Parameters:
object
- the object to use to initialize this message- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
-
createStreamMessage
StreamMessage createStreamMessage() throws JMSException
Creates aStreamMessage
object. AStreamMessage
object is used to send a self-defining stream of primitive values in the Java programming language.- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
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createTextMessage
TextMessage createTextMessage() throws JMSException
Creates aTextMessage
object. ATextMessage
object is used to send a message containing aString
object.- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
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createTextMessage
TextMessage createTextMessage(java.lang.String text) throws JMSException
Creates an initializedTextMessage
object. ATextMessage
object is used to send a message containing aString
.- Parameters:
text
- the string used to initialize this message- Throws:
JMSException
- if the JMS provider fails to create this message due to some internal error.
-
getTransacted
boolean getTransacted() throws JMSException
Indicates whether the session is in transacted mode.- Returns:
- true if the session is in transacted mode
- Throws:
JMSException
- if the JMS provider fails to return the transaction mode due to some internal error.
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getAcknowledgeMode
int getAcknowledgeMode() throws JMSException
Returns the acknowledgement mode of the session. The acknowledgement mode is set at the time that the session is created. If the session is transacted, the acknowledgement mode is ignored.- Returns:
- If the session is not transacted, returns the current acknowledgement mode for the session. If the session is transacted, returns SESSION_TRANSACTED.
- Throws:
JMSException
- if the JMS provider fails to return the acknowledgment mode due to some internal error.- Since:
- 1.1
- See Also:
Connection.createSession(boolean, int)
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commit
void commit() throws JMSException
Commits all messages done in this transaction and releases any locks currently held.- Throws:
JMSException
- if the JMS provider fails to commit the transaction due to some internal error.TransactionRolledBackException
- if the transaction is rolled back due to some internal error during commit.IllegalStateException
- if the method is not called by a transacted session.
-
rollback
void rollback() throws JMSException
Rolls back any messages done in this transaction and releases any locks currently held.- Throws:
JMSException
- if the JMS provider fails to roll back the transaction due to some internal error.IllegalStateException
- if the method is not called by a transacted session.
-
close
void close() throws JMSException
Closes the session.Since a provider may allocate some resources on behalf of a session outside the JVM, clients should close the resources when they are not needed. Relying on garbage collection to eventually reclaim these resources may not be timely enough.
There is no need to close the producers and consumers of a closed session.
This call will block until a
receive
call or message listener in progress has completed. A blocked message consumerreceive
call returnsnull
when this session is closed.Closing a transacted session must roll back the transaction in progress.
This method is the only
Session
method that can be called concurrently.Invoking any other
Session
method on a closed session must throw aJMSException.IllegalStateException
. Closing a closed session must not throw an exception.- Throws:
JMSException
- if the JMS provider fails to close the session due to some internal error.
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recover
void recover() throws JMSException
Stops message delivery in this session, and restarts message delivery with the oldest unacknowledged message.All consumers deliver messages in a serial order. Acknowledging a received message automatically acknowledges all messages that have been delivered to the client.
Restarting a session causes it to take the following actions:
- Stop message delivery
- Mark all messages that might have been delivered but not acknowledged as "redelivered"
- Restart the delivery sequence including all unacknowledged messages that had been previously delivered. Redelivered messages do not have to be delivered in exactly their original delivery order.
- Throws:
JMSException
- if the JMS provider fails to stop and restart message delivery due to some internal error.IllegalStateException
- if the method is called by a transacted session.
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getMessageListener
MessageListener getMessageListener() throws JMSException
Returns the session's distinguished message listener (optional).- Returns:
- the message listener associated with this session
- Throws:
JMSException
- if the JMS provider fails to get the message listener due to an internal error.- See Also:
setMessageListener(javax.jms.MessageListener)
,ServerSessionPool
,ServerSession
-
setMessageListener
void setMessageListener(MessageListener listener) throws JMSException
Sets the session's distinguished message listener (optional).When the distinguished message listener is set, no other form of message receipt in the session can be used; however, all forms of sending messages are still supported.
This is an expert facility not used by regular JMS clients.
- Parameters:
listener
- the message listener to associate with this session- Throws:
JMSException
- if the JMS provider fails to set the message listener due to an internal error.- See Also:
getMessageListener()
,ServerSessionPool
,ServerSession
-
run
void run()
Optional operation, intended to be used only by Application Servers, not by ordinary JMS clients.- Specified by:
run
in interfacejava.lang.Runnable
- See Also:
ServerSession
-
createProducer
MessageProducer createProducer(Destination destination) throws JMSException
Creates aMessageProducer
to send messages to the specified destination.A client uses a
MessageProducer
object to send messages to a destination. SinceQueue
andTopic
both inherit fromDestination
, they can be used in the destination parameter to create aMessageProducer
object.- Parameters:
destination
- theDestination
to send to, or null if this is a producer which does not have a specified destination.- Throws:
JMSException
- if the session fails to create a MessageProducer due to some internal error.InvalidDestinationException
- if an invalid destination is specified.- Since:
- 1.1
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createConsumer
MessageConsumer createConsumer(Destination destination) throws JMSException
Creates aMessageConsumer
for the specified destination. SinceQueue
andTopic
both inherit fromDestination
, they can be used in the destination parameter to create aMessageConsumer
.- Parameters:
destination
- theDestination
to access.- Throws:
JMSException
- if the session fails to create a consumer due to some internal error.InvalidDestinationException
- if an invalid destination is specified.- Since:
- 1.1
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createConsumer
MessageConsumer createConsumer(Destination destination, java.lang.String messageSelector) throws JMSException
Creates aMessageConsumer
for the specified destination, using a message selector. SinceQueue
andTopic
both inherit fromDestination
, they can be used in the destination parameter to create aMessageConsumer
.A client uses a
MessageConsumer
object to receive messages that have been sent to a destination.- Parameters:
destination
- theDestination
to accessmessageSelector
- 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.- Throws:
JMSException
- if the session fails to create a MessageConsumer due to some internal error.InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.- Since:
- 1.1
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createConsumer
MessageConsumer createConsumer(Destination destination, java.lang.String messageSelector, boolean NoLocal) throws JMSException
CreatesMessageConsumer
for the specified destination, using a message selector. This method can specify whether messages published by its own connection should be delivered to it, if the destination is a topic.Since
Queue
andTopic
both inherit fromDestination
, they can be used in the destination parameter to create aMessageConsumer
.A client uses a
MessageConsumer
object to receive messages that have been published to a destination.In some cases, a connection may both publish and subscribe to a topic. The consumer
NoLocal
attribute allows a consumer to inhibit the delivery of messages published by its own connection. The default value for this attribute is False. ThenoLocal
value must be supported by destinations that are topics.- Parameters:
destination
- theDestination
to accessmessageSelector
- 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 true, and the destination is a topic, inhibits the delivery of messages published by its own connection. The behavior forNoLocal
is not specified if the destination is a queue.- Throws:
JMSException
- if the session fails to create a MessageConsumer due to some internal error.InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.- Since:
- 1.1
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createQueue
Queue createQueue(java.lang.String queueName) throws JMSException
Creates a queue identity given aQueue
name.This facility is provided for the rare cases where clients need to dynamically manipulate queue identity. It allows the creation of a queue 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 queue. The physical creation of queues is an administrative task and is not to be initiated by the JMS API. The one exception is the creation of temporary queues, which is accomplished with the
createTemporaryQueue
method.- Parameters:
queueName
- the name of thisQueue
- Returns:
- a
Queue
with the given name - Throws:
JMSException
- if the session fails to create a queue due to some internal error.- Since:
- 1.1
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createTopic
Topic createTopic(java.lang.String topicName) throws JMSException
Creates a topic identity given aTopic
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.- Parameters:
topicName
- the name of thisTopic
- Returns:
- a
Topic
with the given name - Throws:
JMSException
- if the session fails to create a topic due to some internal error.- Since:
- 1.1
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createDurableSubscriber
TopicSubscriber createDurableSubscriber(Topic topic, java.lang.String name) throws JMSException
Creates a durable subscriber to the specified topic.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 subscriber is equivalent to unsubscribing (deleting) the old one and creating a new one.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 non-temporaryTopic
to subscribe toname
- the name used to identify this subscription- Throws:
JMSException
- if the session fails to create a subscriber due to some internal error.InvalidDestinationException
- if an invalid topic is specified.- Since:
- 1.1
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createDurableSubscriber
TopicSubscriber createDurableSubscriber(Topic topic, java.lang.String name, java.lang.String messageSelector, boolean noLocal) throws JMSException
Creates a durable subscriber to the specified topic, using a message selector and specifying whether messages published by its own connection should be delivered to it.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 which 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. An inactive durable subscriber is one that exists but does not currently have a message consumer associated with it.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 subscriber is equivalent to unsubscribing (deleting) the old one and creating a new one.- Parameters:
topic
- the non-temporaryTopic
to subscribe toname
- the name used to identify this subscriptionmessageSelector
- 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.- Since:
- 1.1
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createBrowser
QueueBrowser createBrowser(Queue queue) throws JMSException
Creates aQueueBrowser
object to peek at the messages on the specified queue.- Parameters:
queue
- thequeue
to access- Throws:
JMSException
- if the session fails to create a browser due to some internal error.InvalidDestinationException
- if an invalid destination is specified- Since:
- 1.1
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createBrowser
QueueBrowser createBrowser(Queue queue, java.lang.String messageSelector) throws JMSException
Creates aQueueBrowser
object to peek at the messages on the specified queue using a message selector.- Parameters:
queue
- thequeue
to accessmessageSelector
- 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.- Throws:
JMSException
- if the session fails to create a browser due to some internal error.InvalidDestinationException
- if an invalid destination is specifiedInvalidSelectorException
- if the message selector is invalid.- Since:
- 1.1
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createTemporaryQueue
TemporaryQueue createTemporaryQueue() throws JMSException
Creates aTemporaryQueue
object. Its lifetime will be that of theConnection
unless it is deleted earlier.- Returns:
- a temporary queue identity
- Throws:
JMSException
- if the session fails to create a temporary queue due to some internal error.- Since:
- 1.1
-
createTemporaryTopic
TemporaryTopic createTemporaryTopic() throws JMSException
Creates aTemporaryTopic
object. Its lifetime will be that of theConnection
unless it is deleted earlier.- Returns:
- a temporary topic identity
- Throws:
JMSException
- if the session fails to create a temporary topic due to some internal error.- Since:
- 1.1
-
unsubscribe
void unsubscribe(java.lang.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
MessageConsumer
orTopicSubscriber
for the subscription, or while a consumed message is part of a pending transaction or has not been acknowledged in the 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.- Since:
- 1.1
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