javax.xml.xquery

Interface PooledXQConnection

public interface PooledXQConnection

An object that provides hooks for connection pool management. A 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.

Method Summary

Methods

Modifier and Type	Method and Description
void	addConnectionEventListener(XQConnectionEventListener listener) Registers the given event listener so that it will be notified when an event occurs on this PooledXQConnection object.
void	close() Closes the physical connection that this PooledXQConnection object represents.
XQConnection	getConnection() Creates and returns an XQConnection object that is a handle for the physical connection that this PooledXQConnection object represents.
void	removeConnectionEventListener(XQConnectionEventListener listener) Removes the given event listener from the list of components that will be notified when an event occurs on this PooledXQConnection object.

Method Detail

getConnection

XQConnection getConnection()
                           throws XQException

Creates and returns an XQConnection object that is a handle for the physical connection that this PooledXQConnection object represents. The connection pool manager calls this method when an application has called the XQDataSource method getConnection and there are no PooledXQConnection objects available.

Returns:

an XQConnection object that is a handle to this PooledXQConnection object

Throws:

XQException - if a datasource access error occurs

close

void close()
           throws XQException

Closes the physical connection that this PooledXQConnection 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

addConnectionEventListener

void addConnectionEventListener(XQConnectionEventListener listener)

Registers the given event listener so that it will be notified when an event occurs on this PooledXQConnection object.

Parameters:

listener - a component, usually the connection pool manager, that has implemented the XQConnectionEventListener interface and wants to be notified when the connection is closed or has an error

See Also:

removeConnectionEventListener(javax.xml.xquery.XQConnectionEventListener)

removeConnectionEventListener

void removeConnectionEventListener(XQConnectionEventListener listener)

Removes the given event listener from the list of components that will be notified when an event occurs on this PooledXQConnection object.

Parameters:

listener - a component, usually the connection pool manager, that has implemented the XQConnectionEventListener interface and been registered with this PooledXQConnection object as a listener

See Also:

addConnectionEventListener(javax.xml.xquery.XQConnectionEventListener)