Interface Connection
- All Superinterfaces:
AutoCloseable
- All Known Subinterfaces:
QueueConnection
,TopicConnection
,XAConnection
,XAQueueConnection
,XATopicConnection
Connection
object is a client's active connection to its JMS
provider. It typically allocates provider resources outside the Java virtual
machine (JVM).
Connections support concurrent use.
A connection serves several purposes:
- It encapsulates an open connection with a JMS provider. It typically represents an open TCP/IP socket between a client and the service provider software.
- Its creation is where client authentication takes place.
- It can specify a unique client identifier.
- It provides a
ConnectionMetaData
object. - It supports an optional
ExceptionListener
object.
Because the creation of a connection involves setting up authentication and communication, a connection is a relatively heavyweight object. Most clients will do all their messaging with a single connection. Other more advanced applications may use several connections. The JMS API does not architect a reason for using multiple connections; however, there may be operational reasons for doing so.
A JMS client typically creates a connection, one or more sessions, and a number of message producers and consumers. When a connection is created, it is in stopped mode. That means that no messages are being delivered.
It is typical to leave the connection in stopped mode until setup
is complete (that is, until all message consumers have been
created). At that point, the client calls
the connection's start
method, and messages begin arriving at
the connection's consumers. This setup
convention minimizes any client confusion that may result from
asynchronous message delivery while the client is still in the process
of setting itself up.
A connection can be started immediately, and the setup can be done afterwards. Clients that do this must be prepared to handle asynchronous message delivery while they are still in the process of setting up.
A message producer can send messages while a connection is stopped.
- Since:
- JMS 1.0
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes the connection.createConnectionConsumer
(Destination destination, String messageSelector, ServerSessionPool sessionPool, int maxMessages) Creates a connection consumer for this connection (optional operation) on the specific destination.createDurableConnectionConsumer
(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) Creates a connection consumer for this connection (optional operation) on the specific topic using an unshared durable subscription with the specified name.Creates aSession
object, specifying no arguments.createSession
(boolean transacted, int acknowledgeMode) Creates aSession
object, specifyingtransacted
andacknowledgeMode
.createSession
(int sessionMode) Creates aSession
object, specifyingsessionMode
.createSharedConnectionConsumer
(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) Creates a connection consumer for this connection (optional operation) on the specific topic using a shared non-durable subscription with the specified name.createSharedDurableConnectionConsumer
(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) Creates a connection consumer for this connection (optional operation) on the specific topic using a shared durable subscription with the specified name.Gets the client identifier for this connection.Gets theExceptionListener
object for this connection.Gets the metadata for this connection.void
setClientID
(String clientID) Sets the client identifier for this connection.void
setExceptionListener
(ExceptionListener listener) Sets an exception listener for this connection.void
start()
Starts (or restarts) a connection's delivery of incoming messages.void
stop()
Temporarily stops a connection's delivery of incoming messages.
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Method Details
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createSession
Creates aSession
object, specifyingtransacted
andacknowledgeMode
.This method has been superseded by the method
createSession(int sessionMode)
which specifies the same information using a single argument, and by the methodcreateSession()
which is for use in a Java EE JTA transaction. Applications should consider using those methods instead of this one.The effect of setting the
transacted
andacknowledgeMode
arguments depends on whether this method is called in a Java SE environment, in the Java EE application client container, or in the Java EE web or EJB container. If this method is called in the Java EE web or EJB container then the effect of setting the transacted} andacknowledgeMode
arguments also depends on whether or not there is an active JTA transaction in progress.In a Java SE environment or in the Java EE application client container:
- If
transacted
is set totrue
then the session will use a local transaction which may subsequently be committed or rolled back by calling the session'scommit
orrollback
methods. The argumentacknowledgeMode
is ignored. - If
transacted
is set tofalse
then the session will be non-transacted. In this case the argumentacknowledgeMode
is used to specify how messages received by this session will be acknowledged. The permitted values areSession.CLIENT_ACKNOWLEDGE
,Session.AUTO_ACKNOWLEDGE
andSession.DUPS_OK_ACKNOWLEDGE
. For a definition of the meaning of these acknowledgement modes see the links below.
In a Java EE web or EJB container, when there is an active JTA transaction in progress:
- Both arguments
transacted
andacknowledgeMode
are ignored. The session will participate in the JTA transaction and will be committed or rolled back when that transaction is committed or rolled back, not by calling the session'scommit
orrollback
methods. Since both arguments are ignored, developers are recommended to usecreateSession()
, which has no arguments, instead of this method.
In the Java EE web or EJB container, when there is no active JTA transaction in progress:
- The argument
transacted
is ignored. The session will always be non-transacted, using one of the two acknowledgement modes AUTO_ACKNOWLEDGE and DUPS_OK_ACKNOWLEDGE. - The argument
acknowledgeMode
is used to specify how messages received by this session will be acknowledged. The only permitted values in this case areSession.AUTO_ACKNOWLEDGE
andSession.DUPS_OK_ACKNOWLEDGE
. The valueSession.CLIENT_ACKNOWLEDGE
may not be used. For a definition of the meaning of these acknowledgement modes see the links below.
Applications running in the Java EE web and EJB containers must not attempt to create more than one active (not closed)
Session
object per connection. If this method is called in a Java EE web or EJB container when an activeSession
object already exists for this connection then aJMSException
will be thrown.- Parameters:
transacted
- indicates whether the session will use a local transaction. If this method is called in the Java EE web or EJB container then this argument is ignored.acknowledgeMode
- indicates how messages received by the session will be acknowledged.- If this method is called in a Java SE environment or in the Java EE application client container,
the permitted values are
Session.CLIENT_ACKNOWLEDGE
,Session.AUTO_ACKNOWLEDGE
andSession.DUPS_OK_ACKNOWLEDGE
. - If this method is called in the Java EE web or EJB container when there is an active JTA transaction in progress then this argument is ignored.
- If this method is called in the Java EE web or EJB container when there is no active JTA transaction in progress, the permitted values are
Session.AUTO_ACKNOWLEDGE
andSession.DUPS_OK_ACKNOWLEDGE
. In this caseSession.CLIENT_ACKNOWLEDGE
is not permitted.
- If this method is called in a Java SE environment or in the Java EE application client container,
the permitted values are
- Returns:
- a newly created session
- Throws:
JMSException
- if theConnection
object fails to create a session due to- some internal error,
- lack of support for the specific transaction and acknowledgement mode, or
- because this method is being called in a Java EE web or EJB application and an active session already exists for this connection.
- Since:
- JMS 1.1
- See Also:
- If
-
createSession
Creates aSession
object, specifyingsessionMode
.The effect of setting the
sessionMode
argument depends on whether this method is called in a Java SE environment, in the Java EE application client container, or in the Java EE web or EJB container. If this method is called in the Java EE web or EJB container then the effect of setting thesessionMode
argument also depends on whether or not there is an active JTA transaction in progress.In a Java SE environment or in the Java EE application client container:
- If
sessionMode
is set toSession.SESSION_TRANSACTED
then the session will use a local transaction which may subsequently be committed or rolled back by calling the session'scommit
orrollback
methods. - If
sessionMode
is set to any ofSession.CLIENT_ACKNOWLEDGE
,Session.AUTO_ACKNOWLEDGE
orSession.DUPS_OK_ACKNOWLEDGE
. then the session will be non-transacted and messages received by this session will be acknowledged according to the value ofsessionMode
. For a definition of the meaning of these acknowledgement modes see the links below.
In a Java EE web or EJB container, when there is an active JTA transaction in progress:
- The argument
sessionMode
is ignored. The session will participate in the JTA transaction and will be committed or rolled back when that transaction is committed or rolled back, not by calling the session'scommit
orrollback
methods. Since the argument is ignored, developers are recommended to usecreateSession()
, which has no arguments, instead of this method.
In the Java EE web or EJB container, when there is no active JTA transaction in progress:
- The argument
acknowledgeMode
must be set to either ofSession.AUTO_ACKNOWLEDGE
orSession.DUPS_OK_ACKNOWLEDGE
. The session will be non-transacted and messages received by this session will be acknowledged automatically according to the value ofacknowledgeMode
. For a definition of the meaning of these acknowledgement modes see the links below. The valuesSession.SESSION_TRANSACTED
andSession.CLIENT_ACKNOWLEDGE
may not be used.
Applications running in the Java EE web and EJB containers must not attempt to create more than one active (not closed)
Session
object per connection. If this method is called in a Java EE web or EJB container when an activeSession
object already exists for this connection then aJMSException
will be thrown.- Parameters:
sessionMode
- indicates which of four possible session modes will be used.- If this method is called in a Java SE environment or in the Java EE application client container,
the permitted values are
Session.SESSION_TRANSACTED
,Session.CLIENT_ACKNOWLEDGE
,Session.AUTO_ACKNOWLEDGE
andSession.DUPS_OK_ACKNOWLEDGE
. - If this method is called in the Java EE web or EJB container when there is an active JTA transaction in progress then this argument is ignored.
- If this method is called in the Java EE web or EJB container when there is no active JTA transaction in progress, the permitted values are
Session.AUTO_ACKNOWLEDGE
andSession.DUPS_OK_ACKNOWLEDGE
. In this case the valuesSession.TRANSACTED
andSession.CLIENT_ACKNOWLEDGE
are not permitted.
- If this method is called in a Java SE environment or in the Java EE application client container,
the permitted values are
- Returns:
- a newly created session
- Throws:
JMSException
- if theConnection
object fails to create a session due to- some internal error,
- lack of support for the specific transaction and acknowledgement mode, or
- because this method is being called in a Java EE web or EJB application and an active session already exists for this connection.
- Since:
- JMS 2.0
- See Also:
- If
-
createSession
Creates aSession
object, specifying no arguments.The behaviour of the session that is created depends on whether this method is called in a Java SE environment, in the Java EE application client container, or in the Java EE web or EJB container. If this method is called in the Java EE web or EJB container then the behaviour of the session also depends on whether or not there is an active JTA transaction in progress.
In a Java SE environment or in the Java EE application client container:
- The session will be non-transacted and received messages will be acknowledged automatically
using an acknowledgement mode of
Session.AUTO_ACKNOWLEDGE
For a definition of the meaning of this acknowledgement mode see the link below.
In a Java EE web or EJB container, when there is an active JTA transaction in progress:
- The session will participate in the JTA transaction and will be committed or rolled back
when that transaction is committed or rolled back,
not by calling the session's
commit
orrollback
methods.
In the Java EE web or EJB container, when there is no active JTA transaction in progress:
- The session will be non-transacted and received messages will be acknowledged automatically
using an acknowledgement mode of
Session.AUTO_ACKNOWLEDGE
For a definition of the meaning of this acknowledgement mode see the link below.
Applications running in the Java EE web and EJB containers must not attempt to create more than one active (not closed)
Session
object per connection. If this method is called in a Java EE web or EJB container when an activeSession
object already exists for this connection then aJMSException
will be thrown.- Returns:
- a newly created session
- Throws:
JMSException
- if theConnection
object fails to create a session due to- some internal error or
- because this method is being called in a Java EE web or EJB application and an active session already exists for this connection.
- Since:
- JMS 2.0
- See Also:
- The session will be non-transacted and received messages will be acknowledged automatically
using an acknowledgement mode of
-
getClientID
Gets the client identifier for this connection.This value is specific to the JMS provider. It is either preconfigured by an administrator in a
ConnectionFactory
object or assigned dynamically by the application by calling thesetClientID
method.- Returns:
- the unique client identifier
- Throws:
JMSException
- if the JMS provider fails to return the client ID for this connection due to some internal error.
-
setClientID
Sets the client identifier for this connection.The preferred way to assign a JMS client's client identifier is for it to be configured in a client-specific
ConnectionFactory
object and transparently assigned to theConnection
object it creates.Alternatively, a client can set a connection's client identifier using a provider-specific value. The facility to set a connection's client identifier explicitly is not a mechanism for overriding the identifier that has been administratively configured. It is provided for the case where no administratively specified identifier exists. If one does exist, an attempt to change it by setting it must throw an
IllegalStateException
. If a client sets the client identifier explicitly, it must do so immediately after it creates the connection and before any other action on the connection is taken. After this point, setting the client identifier is a programming error that should throw anIllegalStateException
.The purpose of the client identifier is to associate a connection and its objects with a state maintained on behalf of the client by a provider. The only such state identified by the JMS API is that required to support durable subscriptions.
If another connection with the same
clientID
is already running when this method is called, the JMS provider should detect the duplicate ID and throw anInvalidClientIDException
.This method must not be used in a Java EE web or EJB application. Doing so may cause a
JMSException
to be thrown though this is not guaranteed.- Parameters:
clientID
- the unique client identifier- Throws:
JMSException
- if the JMS provider fails to set the client ID for the the connection for one of the following reasons:- an internal error has occurred or
- this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)
InvalidClientIDException
- if the JMS client specifies an invalid or duplicate client ID.IllegalStateException
- if the JMS client attempts to set a connection's client ID at the wrong time or when it has been administratively configured.
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getMetaData
Gets the metadata for this connection.- Returns:
- the connection metadata
- Throws:
JMSException
- if the JMS provider fails to get the connection metadata for this connection.- See Also:
-
getExceptionListener
Gets theExceptionListener
object for this connection. Not everyConnection
has anExceptionListener
associated with it.- Returns:
- the
ExceptionListener
for this connection, or null. if noExceptionListener
is associated with this connection. - Throws:
JMSException
- if the JMS provider fails to get theExceptionListener
for this connection.- See Also:
-
setExceptionListener
Sets an exception listener for this connection.If a JMS provider detects a serious problem with a connection, it informs the connection's
ExceptionListener
, if one has been registered. It does this by calling the listener'sonException
method, passing it aJMSException
object describing the problem.An exception listener allows a client to be notified of a problem asynchronously. Some connections only consume messages, so they would have no other way to learn their connection has failed.
A connection serializes execution of its
ExceptionListener
.A JMS provider should attempt to resolve connection problems itself before it notifies the client of them.
This method must not be used in a Java EE web or EJB application. Doing so may cause a
JMSException
to be thrown though this is not guaranteed.- Parameters:
listener
- the exception listener- Throws:
JMSException
- if the JMS provider fails to set the exception listener for one of the following reasons:- an internal error has occurred or
- this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)
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start
Starts (or restarts) a connection's delivery of incoming messages. A call tostart
on a connection that has already been started is ignored.- Throws:
JMSException
- if the JMS provider fails to start message delivery due to some internal error.- See Also:
-
stop
Temporarily stops a connection's delivery of incoming messages. Delivery can be restarted using the connection'sstart
method. When the connection is stopped, delivery to all the connection's message consumers is inhibited: synchronous receives block, and messages are not delivered to message listeners.This call blocks until receives and/or message listeners in progress have completed.
Stopping a connection has no effect on its ability to send messages. A call to
stop
on a connection that has already been stopped is ignored.A call to
stop
must not return until delivery of messages has paused. This means that a client can rely on the fact that none of its message listeners will be called and that all threads of control waiting forreceive
calls to return will not return with a message until the connection is restarted. The receive timers for a stopped connection continue to advance, so receives may time out while the connection is stopped.If message listeners are running when
stop
is invoked, thestop
call must wait until all of them have returned before it may return. While these message listeners are completing, they must have the full services of the connection available to them.A message listener must not attempt to stop its own connection as this would lead to deadlock. The JMS provider must detect this and throw a IllegalStateException.
For the avoidance of doubt, if an exception listener for this connection is running when
stop
is invoked, there is no requirement for thestop
call to wait until the exception listener has returned before it may return.This method must not be used in a Java EE web or EJB application. Doing so may cause a
JMSException
to be thrown though this is not guaranteed.- Throws:
IllegalStateException
- this method has been called by a MessageListener on its own ConnectionJMSException
- if the JMS provider fails to stop message delivery for one of the following reasons:- an internal error has occurred or
- this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)
- See Also:
-
close
Closes the connection.Since a provider typically allocates significant resources outside the JVM on behalf of a connection, clients should close these 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 sessions, producers, and consumers of a closed connection.
Closing a connection causes all temporary destinations to be deleted.
When this method is invoked, it should not return until message processing has been shut down in an orderly fashion. This means that all message listeners that may have been running have returned, and that all pending receives have returned. A close terminates all pending message receives on the connection's sessions' consumers. The receives may return with a message or with null, depending on whether there was a message available at the time of the close. If one or more of the connection's sessions' message listeners is processing a message at the time when connection
close
is invoked, all the facilities of the connection and its sessions must remain available to those listeners until they return control to the JMS provider.This method must not return until any incomplete asynchronous send operations for this Connection have been completed and any CompletionListener callbacks have returned. Incomplete sends should be allowed to complete normally unless an error occurs.
For the avoidance of doubt, if an exception listener for this connection is running when
close
is invoked, there is no requirement for theclose
call to wait until the exception listener has returned before it may return.Closing a connection causes any of its sessions' transactions in progress to be rolled back. In the case where a session's work is coordinated by an external transaction manager, a session's
commit
androllback
methods are not used and the result of a closed session's work is determined later by the transaction manager. Closing a connection does NOT force an acknowledgment of client-acknowledged sessions.A message listener must not attempt to close its own connection as this would lead to deadlock. The JMS provider must detect this and throw a IllegalStateException.
A CompletionListener callback method must not call close on its own Connection. Doing so will cause an IllegalStateException to be thrown.
Invoking the
acknowledge
method of a received message from a closed connection's session must throw anIllegalStateException
. Closing a closed connection must NOT throw an exception.- Specified by:
close
in interfaceAutoCloseable
- Throws:
IllegalStateException
-- this method has been called by a MessageListener on its own Connection
- this method has been called by a CompletionListener callback method on its own Connection
JMSException
- if the JMS provider fails to close the connection due to some internal error. For example, a failure to release resources or to close a socket connection can cause this exception to be thrown.
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createConnectionConsumer
ConnectionConsumer createConnectionConsumer(Destination destination, String messageSelector, ServerSessionPool sessionPool, int maxMessages) throws JMSException Creates a connection consumer for this connection (optional operation) on the specific destination.This is an expert facility not used by ordinary JMS clients.
This method must not be used in a Java EE web or EJB application. Doing so may cause a
JMSException
to be thrown though this is not guaranteed.- Parameters:
destination
- the destination 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.sessionPool
- the server session pool to associate with this connection consumermaxMessages
- the maximum number of messages that can be assigned to a server session at one time- Returns:
- the connection consumer
- Throws:
InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.JMSException
- if theConnection
object fails to create a connection consumer for one of the following reasons:- an internal error has occurred
- invalid arguments for
sessionPool
andmessageSelector
or - this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)
- Since:
- JMS 1.1
- See Also:
-
createDurableConnectionConsumer
ConnectionConsumer createDurableConnectionConsumer(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) throws JMSException Creates a connection consumer for this connection (optional operation) on the specific topic using an unshared durable subscription with the specified name.This is an expert facility not used by ordinary JMS clients.
This method must not be used in a Java EE web or EJB application. Doing so may cause a
JMSException
to be thrown though this is not guaranteed.- Parameters:
topic
- topic to accesssubscriptionName
- the name used to identify the unshared durable 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.sessionPool
- the server session pool to associate with this durable connection consumermaxMessages
- the maximum number of messages that can be assigned to a server session at one time- Returns:
- the durable connection consumer
- Throws:
IllegalStateException
- if called on aQueueConnection
InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.JMSException
- if theConnection
object fails to create a connection consumer for one of the following reasons:- an internal error has occurred
- invalid arguments
for
sessionPool
andmessageSelector
or - this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)
- Since:
- JMS 1.1
- See Also:
-