Interface PooledXQConnection
PooledXQConnection
object
represents a physical connection to a data source. The connection
can be recycled rather than being closed when an application is
finished with it, thus reducing the number of connections that
need to be made.
An application programmer does not use the PooledXQConnection
interface directly; rather, it is used by a middle tier infrastructure
that manages the pooling of connections.
When an application calls the method XQDataSource.getConnection
,
it gets back an XQConnection
object. If connection pooling is
being done, that XQConnection
object is actually a handle to
a PooledXQConnection
object, which is a physical connection.
The connection pool manager, typically the application server, maintains
a pool of PooledXQConnection
objects. If there is a
PooledXQConnection
object available in the pool, the
connection pool manager returns an XQConnection
object that
is a handle to that physical connection.
If no PooledXQConnection
object is available, the
connection pool manager calls the ConnectionPoolXQDataSource
method getPooledConnection
to create a new physical connection and
returns a handle to it.
When an application closes a connection, it calls the XQConnection
method close
. When connection pooling is being done,
the connection pool manager is notified because it has registered itself as
an XQConnectionEventListener
object using the
PooledXQConnection
method addConnectionEventListener
.
The connection pool manager deactivates the handle to
the PooledXQConnection
object and returns the
PooledXQConnection
object to the pool of connections so that
it can be used again. Thus, when an application closes its connection,
the underlying physical connection is recycled rather than being closed.
The physical connection is not closed until the connection pool manager
calls the PooledXQConnection
method close
.
This method is generally called to have an orderly shutdown of the server or
if a fatal error has made the physical connection unusable.
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Method Summary
Modifier and TypeMethodDescriptionvoid
Registers the given event listener so that it will be notified when an event occurs on thisPooledXQConnection
object.void
close()
Closes the physical connection that thisPooledXQConnection
object represents.Creates and returns anXQConnection
object that is a handle for the physical connection that thisPooledXQConnection
object represents.void
Removes the given event listener from the list of components that will be notified when an event occurs on thisPooledXQConnection
object.
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Method Details
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getConnection
Creates and returns anXQConnection
object that is a handle for the physical connection that thisPooledXQConnection
object represents. The connection pool manager calls this method when an application has called theXQDataSource
methodgetConnection
and there are noPooledXQConnection
objects available.- Returns:
- an
XQConnection
object that is a handle to thisPooledXQConnection
object - Throws:
XQException
- if a datasource access error occurs
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close
Closes the physical connection that thisPooledXQConnection
object represents. An application never calls this method directly; it is called by the connection pool manager.- Throws:
XQException
- if a datasource access error occurs
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addConnectionEventListener
Registers the given event listener so that it will be notified when an event occurs on thisPooledXQConnection
object.- Parameters:
listener
- a component, usually the connection pool manager, that has implemented theXQConnectionEventListener
interface and wants to be notified when the connection is closed or has an error- See Also:
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removeConnectionEventListener
Removes the given event listener from the list of components that will be notified when an event occurs on thisPooledXQConnection
object.- Parameters:
listener
- a component, usually the connection pool manager, that has implemented theXQConnectionEventListener
interface and been registered with thisPooledXQConnection
object as a listener- See Also:
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