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A 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:
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 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.
ConnectionFactory, 
QueueConnection, 
TopicConnection| Method Summary | |
|  void | close()Closes the connection. | 
|  ConnectionConsumer | createConnectionConsumer(Destination destination,
                         java.lang.String messageSelector,
                         ServerSessionPool sessionPool,
                         int maxMessages)Creates a connection consumer for this connection (optional operation). | 
|  ConnectionConsumer | createDurableConnectionConsumer(Topic topic,
                                java.lang.String subscriptionName,
                                java.lang.String messageSelector,
                                ServerSessionPool sessionPool,
                                int maxMessages)Create a durable connection consumer for this connection (optional operation). | 
|  Session | createSession(boolean transacted,
              int acknowledgeMode)Creates a Sessionobject. | 
|  java.lang.String | getClientID()Gets the client identifier for this connection. | 
|  ExceptionListener | getExceptionListener()Gets the ExceptionListenerobject for this connection. | 
|  ConnectionMetaData | getMetaData()Gets the metadata for this connection. | 
|  void | setClientID(java.lang.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. | 
| Method Detail | 
public Session createSession(boolean transacted,
                             int acknowledgeMode)
                      throws JMSException
Session object.
transacted - indicates whether the session is transactedacknowledgeMode - indicates whether the consumer or the
 client will acknowledge any messages it receives; ignored if the session
 is transacted. Legal values are Session.AUTO_ACKNOWLEDGE, 
 Session.CLIENT_ACKNOWLEDGE, and 
 Session.DUPS_OK_ACKNOWLEDGE.
JMSException - if the Connection object fails
                         to create a session due to some internal error or
                         lack of support for the specific transaction
                         and acknowledgement mode.Session.AUTO_ACKNOWLEDGE, 
Session.CLIENT_ACKNOWLEDGE, 
Session.DUPS_OK_ACKNOWLEDGE
public java.lang.String getClientID()
                             throws JMSException
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 the
 setClientID method.
JMSException - if the JMS provider fails to return
                         the client ID for this connection due
                         to some internal error.
public void setClientID(java.lang.String clientID)
                 throws JMSException
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 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 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
 an InvalidClientIDException.
clientID - the unique client identifier
JMSException - if the JMS provider fails to
                         set the client ID for this connection due
                         to some internal error.
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.
public ConnectionMetaData getMetaData()
                               throws JMSException
JMSException - if the JMS provider fails to
                         get the connection metadata for this connection.ConnectionMetaData
public 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 JMS provider fails to
                         get the ExceptionListener for this 
                         connection.setExceptionListener(javax.jms.ExceptionListener)
public void setExceptionListener(ExceptionListener listener)
                          throws JMSException
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'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 JMS provider should attempt to resolve connection problems itself before it notifies the client of them.
listener - the exception listener
JMSException - if the JMS provider fails to
                         set the exception listener for this connection.
public void start()
           throws JMSException
start on a connection that has already been
 started is ignored.
JMSException - if the JMS provider fails to start
                         message delivery due to some internal error.stop()
public 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.
 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 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.
JMSException - if the JMS provider fails to stop
                         message delivery due to some internal error.start()
public 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. 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. 
 
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. 
 
 
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.
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.
public ConnectionConsumer createConnectionConsumer(Destination destination,
                                                   java.lang.String messageSelector,
                                                   ServerSessionPool sessionPool,
                                                   int maxMessages)
                                            throws JMSException
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
JMSException - if the Connection object fails
                         to create a connection consumer due to some
                         internal error or invalid arguments for 
                         sessionPool and 
                         messageSelector.
InvalidDestinationException - if an invalid destination is specified.
InvalidSelectorException - if the message selector is invalid.ConnectionConsumer
public ConnectionConsumer createDurableConnectionConsumer(Topic topic,
                                                          java.lang.String subscriptionName,
                                                          java.lang.String messageSelector,
                                                          ServerSessionPool sessionPool,
                                                          int maxMessages)
                                                   throws JMSException
topic - topic to accesssubscriptionName - durable subscription namemessageSelector - 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
JMSException - if the Connection object fails
                         to create a connection consumer due to some
                         internal error or invalid arguments for 
                         sessionPool and 
                         messageSelector.
InvalidDestinationException - if an invalid destination
             is specified.
InvalidSelectorException - if the message selector is invalid.ConnectionConsumer| 
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Copyright 2003 Sun Microsystems, Inc. All rights reserved.