org.apache.xalan.lib.sql

Interface ConnectionPool

public interface ConnectionPool

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

Version: 1.0

Author: John Gentilin

Method Summary
voidfreeUnused()
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.
ConnectiongetConnection()
Retrive a database connection from the pool
booleanhasActiveConnections()
Provide an indicator to the PoolManager when the Pool can be removed from the Pool Table.
booleanisEnabled()
Determine if a Connection Pool has been disabled.
voidreleaseConnection(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
voidreleaseConnectionOnError(Connection con)
Provide a mechinism to return a connection to the pool on Error.
voidsetDriver(String d)
The Driver and URL are the only required parmeters.
voidsetMinConnections(int n)
Set tne minimum number of connections that are to be maintained in the pool.
voidsetPassword(String p)
The rest of the protocol parameters can eiter be passed in as just Username and Password or as a property collection.
voidsetPoolEnabled(boolean flag)
The Pool can be Enabled and Disabled.
voidsetProtocol(Properties p)
Used to pass in extra configuration options during the database connect phase.
voidsetURL(String url)
voidsetUser(String u)
booleantestConnection()
Test to see if the connection info is valid to make a real connection to the database.

Method Detail

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.

getConnection

public Connection getConnection()
Retrive a database connection from the pool

Throws: SQLException

hasActiveConnections

public boolean hasActiveConnections()
Provide an indicator to the PoolManager when the Pool can be removed from the Pool Table.

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.

releaseConnection

public 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

Parameters: con

Throws: SQLException

releaseConnectionOnError

public void releaseConnectionOnError(Connection con)
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

Throws: SQLException

setDriver

public void setDriver(String d)
The Driver and URL are the only required parmeters.

Parameters: d

setMinConnections

public void setMinConnections(int n)
Set tne minimum number of connections that are to be maintained in the pool.

Parameters: n

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

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.

setProtocol

public void setProtocol(Properties p)
Used to pass in extra configuration options during the database connect phase.

setURL

public void setURL(String url)

Parameters: url

setUser

public void setUser(String u)

Parameters: u

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.
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