org.apache.xalan.lib.sql
Interface ConnectionPool

All Known Implementing Classes:

DefaultConnectionPool

public interface ConnectionPool

An interface used to build wrapper classes around existing Connection Pool libraries. Title: ConnectionPool

Author:

John Gentilin

Method Summary

void	freeUnused() Start downsizeing the pool, this usally happens right after the pool has been marked as Inactive and we are removing connections that are not currently inuse.
Connection	getConnection() Retrive a database connection from the pool
boolean	hasActiveConnections() Provide an indicator to the PoolManager when the Pool can be removed from the Pool Table.
boolean	isEnabled() Determine if a Connection Pool has been disabled.
void	releaseConnection(Connection con) Return a connection to the pool, the connection may be closed if the pool is inactive or has exceeded the max number of free connections
void	releaseConnectionOnError(Connection con) Provide a mechinism to return a connection to the pool on Error.
void	setDriver(String d) The Driver and URL are the only required parmeters.
void	setMinConnections(int n) Set tne minimum number of connections that are to be maintained in the pool.
void	setPassword(String p) The rest of the protocol parameters can eiter be passed in as just Username and Password or as a property collection.
void	setPoolEnabled(boolean flag) The Pool can be Enabled and Disabled.
void	setProtocol(Properties p) Used to pass in extra configuration options during the database connect phase.
void	setURL(String url)
void	setUser(String u)
boolean	testConnection() Test to see if the connection info is valid to make a real connection to the database.

Method Detail

isEnabled

public boolean isEnabled()

Determine if a Connection Pool has been disabled. If a Connection pool is disabled, then it will only manage connections that are in use.

Returns:

setDriver

public void setDriver(String d)

The Driver and URL are the only required parmeters.

Parameters:

d -

Returns:

setURL

public void setURL(String url)

Parameters:

url -

Returns:

freeUnused

public void freeUnused()

Start downsizeing the pool, this usally happens right after the pool has been marked as Inactive and we are removing connections that are not currently inuse.

Returns:

hasActiveConnections

public boolean hasActiveConnections()

Provide an indicator to the PoolManager when the Pool can be removed from the Pool Table.

Returns:

setPassword

public void setPassword(String p)

The rest of the protocol parameters can eiter be passed in as just Username and Password or as a property collection. If the property collection is used, then the sperate username and password may be ignored, it is up to the wrapper implementation to handle the situation. If the connection information changes while after the pool has been established, the wrapper implementation should ignore the change and throw an error.

Parameters:

p -

Returns:

setUser

public void setUser(String u)

Parameters:

u -

Returns:

setMinConnections

public void setMinConnections(int n)

Set tne minimum number of connections that are to be maintained in the pool.

Parameters:

n -

Returns:

testConnection

public boolean testConnection()

Test to see if the connection info is valid to make a real connection to the database. This method may cause the pool to be crated and filled with min connections.

Returns:

getConnection

public Connection getConnection()
                         throws SQLException

Retrive a database connection from the pool

Returns:

Throws:

SQLException

releaseConnection

public void releaseConnection(Connection con)
                       throws SQLException

Return a connection to the pool, the connection may be closed if the pool is inactive or has exceeded the max number of free connections

Parameters:

con -

Returns:

Throws:

SQLException

releaseConnectionOnError

public void releaseConnectionOnError(Connection con)
                              throws SQLException

Provide a mechinism to return a connection to the pool on Error. A good default behaviour is to close this connection and build a new one to replace it. Some JDBC impl's won't allow you to reuse a connection after an error occurs.

Parameters:

con -

Returns:

Throws:

SQLException

setPoolEnabled

public void setPoolEnabled(boolean flag)

The Pool can be Enabled and Disabled. Disabling the pool closes all the outstanding Unused connections and any new connections will be closed upon release.

Parameters:

flag - Control the Connection Pool. If it is enabled then Connections will actuall be held around. If disabled then all unused connections will be instantly closed and as connections are released they are closed and removed from the pool.

Returns:

setProtocol

public void setProtocol(Properties p)

Used to pass in extra configuration options during the database connect phase.