public interface Connection extends AutoCloseable
Connection
object is a client's active connection to its Jakarta Messaging provider. It typically allocates provider
resources outside the Java virtual machine (JVM).
Connections support concurrent use.
A connection serves several purposes:
ConnectionMetaData
object.
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 Jakarta Messaging API does not architect a reason for using multiple connections; however, there may be operational reasons for doing so.
A Jakarta Messaging 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.
ConnectionFactory
,
QueueConnection
,
TopicConnection
Modifier and Type | Method and Description |
---|---|
void |
close()
Closes the connection.
|
ConnectionConsumer |
createConnectionConsumer(Destination destination,
String messageSelector,
ServerSessionPool sessionPool,
int maxMessages)
Creates a connection consumer for this connection (optional operation) on the specific destination.
|
ConnectionConsumer |
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.
|
Session |
createSession()
Creates a
Session object, specifying no arguments. |
Session |
createSession(boolean transacted,
int acknowledgeMode)
Creates a
Session object, specifying transacted and acknowledgeMode . |
Session |
createSession(int sessionMode)
Creates a
Session object, specifying sessionMode . |
ConnectionConsumer |
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.
|
ConnectionConsumer |
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.
|
String |
getClientID()
Gets the client identifier for this connection.
|
ExceptionListener |
getExceptionListener()
Gets the
ExceptionListener object for this connection. |
ConnectionMetaData |
getMetaData()
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.
|
Session createSession(boolean transacted, int acknowledgeMode) throws JMSException
Session
object, specifying transacted
and acknowledgeMode
.
This method has been superseded by the method createSession(int sessionMode)
which specifies the same
information using a single argument, and by the method createSession()
which is for use in a Jakarta EE JTA
transaction. Applications should consider using those methods instead of this one.
The effect of setting the transacted
and acknowledgeMode
arguments depends on whether this method is
called in a Java SE environment, in the Jakarta EE application client container, or in the Jakarta EE web or EJB container.
If this method is called in the Jakarta EE web or EJB container then the effect of setting the transacted} and
acknowledgeMode
arguments also depends on whether or not there is an active JTA transaction in progress.
In a Java SE environment or in the Jakarta EE application client container:
transacted
is set to true
then the session will use a local transaction which may subsequently
be committed or rolled back by calling the session's commit
or rollback
methods. The argument
acknowledgeMode
is ignored.
transacted
is set to false
then the session will be non-transacted. In this case the argument
acknowledgeMode
is used to specify how messages received by this session will be acknowledged. The permitted
values are Session.CLIENT_ACKNOWLEDGE
, Session.AUTO_ACKNOWLEDGE
and
Session.DUPS_OK_ACKNOWLEDGE
. For a definition of the meaning of these acknowledgement modes see the links
below.
In a Jakarta EE web or EJB container, when there is an active JTA transaction in progress:
transacted
and acknowledgeMode
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's commit
or rollback
methods. Since both arguments are ignored, developers are
recommended to use createSession()
, which has no arguments, instead of this method.
In the Jakarta EE web or EJB container, when there is no active JTA transaction in progress:
transacted
is set to false and acknowledgeMode
is set to JMSContext.AUTO_ACKNOWLEDGE
or Session.DUPS_OK_ACKNOWLEDGE
then the session will be non-transacted and messages will be acknowledged
according to the value of acknowledgeMode
.
transacted
is set to false and acknowledgeMode
is set to JMSContext.CLIENT_ACKNOWLEDGE
then the Jakarta Messaging provider is recommended to ignore the specified parameters and instead provide a non-transacted,
auto-acknowledged session. However the Jakarta Messaging provider may alternatively provide a non-transacted session with client
acknowledgement.
transacted
is set to true, then the Jakarta Messaging provider is recommended to ignore the specified parameters and
instead provide a non-transacted, auto-acknowledged session. However the Jakarta Messaging provider may alternatively provide a
local transacted session.
transacted
to false and acknowledgeMode
to
JMSContext.AUTO_ACKNOWLEDGE
or Session.DUPS_OK_ACKNOWLEDGE
since since applications which set
transacted
to false and set acknowledgeMode
to JMSContext.CLIENT_ACKNOWLEDGE
, or which set
transacted
to true, may not be portable.
Applications running in the Jakarta 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 Jakarta EE web or EJB container when an
active Session
object already exists for this connection then a JMSException
may be thrown.
transacted
- indicates whether the session will use a local transaction, except in the cases described above
when this value is ignored..acknowledgeMode
- when transacted is false, indicates how messages received by the session will be acknowledged,
except in the cases described above when this value is ignored.JMSException
- if the Connection
object fails to create a session due to
Session.AUTO_ACKNOWLEDGE
,
Session.CLIENT_ACKNOWLEDGE
,
Session.DUPS_OK_ACKNOWLEDGE
,
createSession(int)
,
createSession()
Session createSession(int sessionMode) throws JMSException
Session
object, specifying sessionMode
.
The effect of setting the sessionMode
argument depends on whether this method is called in a Java SE
environment, in the Jakarta EE application client container, or in the Jakarta EE web or EJB container. If this method is
called in the Jakarta EE web or EJB container then the effect of setting the sessionMode
argument also depends
on whether or not there is an active JTA transaction in progress.
In a Java SE environment or in the Jakarta EE application client container:
sessionMode
is set to Session.SESSION_TRANSACTED
then the session will use a local transaction
which may subsequently be committed or rolled back by calling the session's commit
or rollback
methods.
sessionMode
is set to any of Session.CLIENT_ACKNOWLEDGE
, Session.AUTO_ACKNOWLEDGE
or
Session.DUPS_OK_ACKNOWLEDGE
. then the session will be non-transacted and messages received by this session
will be acknowledged according to the value of sessionMode
. For a definition of the meaning of these
acknowledgement modes see the links below.
In a Jakarta EE web or EJB container, when there is an active JTA transaction in progress:
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's
commit
or rollback
methods. Since the argument is ignored, developers are recommended to use
createSession()
, which has no arguments, instead of this method.
In the Jakarta EE web or EJB container, when there is no active JTA transaction in progress:
sessionMode
is set to Session.AUTO_ACKNOWLEDGE
or Session.DUPS_OK_ACKNOWLEDGE
then the
session will be non-transacted and messages will be acknowledged according to the value of sessionMode
.
sessionMode
is set to Session.CLIENT_ACKNOWLEDGE
then the Jakarta Messaging provider is recommended to
ignore the specified parameter and instead provide a non-transacted, auto-acknowledged session. However the JMS
provider may alternatively provide a non-transacted session with client acknowledgement.
sessionMode
is set to Session.SESSION_TRANSACTED
, then the Jakarta Messaging provider is recommended to
ignore the specified parameter and instead provide a non-transacted, auto-acknowledged session. However the JMS
provider may alternatively provide a local transacted session.
Session.AUTO_ACKNOWLEDGE
and
Session.DUPS_OK_ACKNOWLEDGE
since applications which use Session.CLIENT_ACKNOWLEDGE
or
Session.SESSION_TRANSACTED
may not be portable.
Applications running in the Jakarta 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 Jakarta EE web or EJB container when an
active Session
object already exists for this connection then a JMSException
may be thrown.
sessionMode
- specifies the session mode that will be used, except in the cases described above when this value
is ignored. Legal values are JMSContext.SESSION_TRANSACTED
, JMSContext.CLIENT_ACKNOWLEDGE
,
JMSContext.AUTO_ACKNOWLEDGE
and JMSContext.DUPS_OK_ACKNOWLEDGE
.JMSException
- if the Connection
object fails to create a session due to
Session.SESSION_TRANSACTED
,
Session.AUTO_ACKNOWLEDGE
,
Session.CLIENT_ACKNOWLEDGE
,
Session.DUPS_OK_ACKNOWLEDGE
,
createSession(boolean, int)
,
createSession()
Session createSession() throws JMSException
Session
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 Jakarta EE application client container, or in the Jakarta EE web or EJB container. If this method is called in the Jakarta 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 Jakarta EE application client container:
Session.AUTO_ACKNOWLEDGE
For a definition of the meaning of this acknowledgement mode
see the link below.
In a Jakarta EE web or EJB container, when there is an active JTA transaction in progress:
commit
or rollback
methods.
In the Jakarta EE web or EJB container, when there is no active JTA transaction in progress:
Session.AUTO_ACKNOWLEDGE
For a definition of the meaning of this acknowledgement mode
see the link below.
Applications running in the Jakarta 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 Jakarta EE web or EJB container when an
active Session
object already exists for this connection then a JMSException
may be thrown.
JMSException
- if the Connection
object fails to create a session due to
Session.AUTO_ACKNOWLEDGE
,
createSession(boolean, int)
,
createSession(int)
String getClientID() throws JMSException
This value is specific to the Jakarta Messaging provider. It is either preconfigured by an administrator in a
ConnectionFactory
object or assigned dynamically by the application by calling the setClientID
method.
JMSException
- if the Jakarta Messaging provider fails to return the client ID for this connection due to some internal
error.void setClientID(String clientID) throws JMSException
The preferred way to assign a Jakarta Messaging client's client identifier is for it to be configured in a client-specific
ConnectionFactory
object and transparently assigned to the Connection
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 an IllegalStateException
.
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 Jakarta Messaging API is that required to support durable subscriptions.
If another connection with the same clientID
is already running when this method is called, the Jakarta Messaging provider
should detect the duplicate ID and throw an InvalidClientIDException
.
This method must not be used in a Jakarta EE web or EJB application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
clientID
- the unique client identifierJMSException
- if the Jakarta Messaging provider fails to set the client ID for the the connection for one of the
following reasons:
InvalidClientIDException
- if the Jakarta Messaging client specifies an invalid or duplicate client ID.IllegalStateException
- if the Jakarta Messaging client attempts to set a connection's client ID at the wrong time or when
it has been administratively configured.ConnectionMetaData getMetaData() throws JMSException
JMSException
- if the Jakarta Messaging provider fails to get the connection metadata for this connection.ConnectionMetaData
ExceptionListener getExceptionListener() throws JMSException
ExceptionListener
object for this connection. Not every Connection
has an
ExceptionListener
associated with it.ExceptionListener
for this connection, or null. if no ExceptionListener
is associated
with this connection.JMSException
- if the Jakarta Messaging provider fails to get the ExceptionListener
for this connection.setExceptionListener(javax.jms.ExceptionListener)
void setExceptionListener(ExceptionListener listener) throws JMSException
If a Jakarta Messaging 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's onException
method, passing it a
JMSException
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 Jakarta Messaging provider should attempt to resolve connection problems itself before it notifies the client of them.
This method must not be used in a Jakarta EE web or EJB application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
listener
- the exception listenerJMSException
- if the Jakarta Messaging provider fails to set the exception listener for one of the following reasons:
void start() throws JMSException
start
on a connection that has
already been started is ignored.JMSException
- if the Jakarta Messaging provider fails to start message delivery due to some internal error.stop()
void stop() throws JMSException
start
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.
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 for
receive
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, the stop
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.
However if the stop
method is called from a message listener on its own connection, then it will either fail
and throw a javax.jms.IllegalStateException
, or it will succeed and stop the connection, blocking until all
other message listeners that may have been running have returned.
Since two alternative behaviors are permitted in this case, applications should avoid calling stop
from a
message listener on its own Connection because this is not portable.
For the avoidance of doubt, if an exception listener for this connection is running when stop
is invoked,
there is no requirement for the stop
call to wait until the exception listener has returned before it may
return.
This method must not be used in a Jakarta EE web or EJB application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
IllegalStateException
- this method has been called by a MessageListener on its own
ConnectionJMSException
- if the Jakarta Messaging provider fails to stop message delivery for one of the following reasons:
start()
void close() throws JMSException
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.
However if the close method is called from a message listener on its own connection, then it will either fail and
throw a javax.jms.IllegalStateException
, or it will succeed and close the connection, blocking until all
other message listeners that may have been running have returned, and all pending receive calls have completed. If
close succeeds and the acknowledge mode of the session is set to AUTO_ACKNOWLEDGE
, the current message will
still be acknowledged automatically when the onMessage
call completes. Since two alternative behaviors are
permitted in this case, applications should avoid calling close from a message listener on its own connection because
this is not portable.
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 Jakarta Messaging 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 the close
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
and rollback
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 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 an
IllegalStateException
. Closing a closed connection must NOT throw an exception.
close
in interface AutoCloseable
IllegalStateException
- JMSException
- if the Jakarta Messaging 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.ConnectionConsumer createConnectionConsumer(Destination destination, String messageSelector, ServerSessionPool sessionPool, int maxMessages) throws JMSException
This is an expert facility not used by ordinary Jakarta Messaging clients.
This method must not be used in a Jakarta EE web or Enterprise Bean application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
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 timeInvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.JMSException
- if the Connection
object fails to create a connection consumer for one of the
following reasons:
sessionPool
and messageSelector
or
ConnectionConsumer
ConnectionConsumer createSharedConnectionConsumer(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) throws JMSException
This is an expert facility not used by ordinary Jakarta Messaging clients.
This method must not be used in a Jakarta EE web or EJB application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
topic
- the topic to accesssubscriptionName
- the name used to identify the shared non-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 connection consumermaxMessages
- the maximum number of messages that can be assigned to a server session at one timeIllegalStateException
- if called on a QueueConnection
InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.JMSException
- if the Connection
object fails to create a connection consumer for one of the
following reasons:
sessionPool
and messageSelector
or
ConnectionConsumer
ConnectionConsumer createDurableConnectionConsumer(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) throws JMSException
This is an expert facility not used by ordinary Jakarta Messaging clients.
This method must not be used in a Jakarta EE web or EJB application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
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 timeIllegalStateException
- if called on a QueueConnection
InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.JMSException
- if the Connection
object fails to create a connection consumer for one of the
following reasons:
sessionPool
and messageSelector
or
ConnectionConsumer
ConnectionConsumer createSharedDurableConnectionConsumer(Topic topic, String subscriptionName, String messageSelector, ServerSessionPool sessionPool, int maxMessages) throws JMSException
This is an expert facility not used by ordinary Jakarta Messaging clients.
This method must not be used in a Jakarta EE web or EJB application. Doing so may cause a JMSException
to be
thrown though this is not guaranteed.
topic
- topic to accesssubscriptionName
- the name used to identify the shared 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 timeIllegalStateException
- if called on a QueueConnection
InvalidDestinationException
- if an invalid destination is specified.InvalidSelectorException
- if the message selector is invalid.JMSException
- if the Connection
object fails to create a connection consumer for one of the
following reasons:
sessionPool
and messageSelector
or
ConnectionConsumer
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