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Class com.studioitech.gulli.MJDBC.dbArbiterConnections

java.lang.Object
   |
   +----com.studioitech.gulli.MJDBC.dbArbiterConnections

public class dbArbiterConnections
extends Object

A Connection represents a session with a specific database. Within the context of a Connection, SQL statements are executed and results are returned.

This package allows user to init a lot of JDBC Connections to a database. These connections are never closed until the end of the user program and they are handled in mutex way: i mean, they are multi-thread safe.

An example of benefit of this, is servlet programming. In servlet model you have an init phase (during which servlet is allocated) a destroy phase (during which servlet is deallocated) and a doGet (or similiar ...). The init and destroy method are called by the HTTP server in single-thread enviroment. The doGet method works in a multi-thread enviroment.

The HTTP server for every incoming GET request directed to servlet create a new thread and execute the doGet code.

By using this package, you can open a lot of connection to the DB during the init phase. Use them in multi-thread safe mode during the doGet call. Only close them when the servlet is discarded from HTTP server.

Benefits are in term of performance. In fact, using traditional cgi-bin like paradigm, for every incoming request you have this cycle:

Open DB
Perform SQL Query and get Results
Close DB

Opening and Close a DB is a very costly operation. This is true in direct access to a given database via a propreatary API, This become most evident if you access the database via the JDBC layer because you have to count the time to load the JDBC driver. So is better to perform these costly operation at the init time once.

Using this package you can move to a new paradigm, for every incoming request you have this cycle:

Get an available connection to the DB and mark it as used
Perform SQL Query and get Results
Mark used connection as available

For a large volume of requests avoiding to load JDBC driver, open and close continuosly means to have a less latency in answering.

dbArbiterConnections(String, String, String, String, int): Constructor of the ArbiterConnections: It opens ncons dbConnection and init their multi-thread safe handling

getAnAvailableCon(): Get an available connection in the opened pool of dbConnection
getNumAllocatedCon(): Get the number of connection in the pool of opened dbConnection
shutdown(): Close all available dbConnection

dbArbiterConnections

 public dbArbiterConnections(String JDBC_DriverName,
                             String url,
                             String usr,
                             String pwd,
                             int ncons) throws SQLException, ClassNotFoundException

Constructor of the ArbiterConnections: It opens ncons dbConnection and init their multi-thread safe handling

Parameters:: JDBC_DriverName - the name of JDBC driver; url - the url to connect database (e.g.: jdbc:postgresql:database ); usr - the name of database's user (e.g.: test); pwd - the password database user (e.g.: test); ncons - number of connection to open
Throws: SQLException: if a database-access error occurs.
Throws: ClassNotFoundException: if the JDBC driver is not available

getAnAvailableCon

 public dbConnection getAnAvailableCon()

Get an available connection in the opened pool of dbConnection

Returns:: dbConnection, the chosen available connection
See Also:: dbConnection

shutdown

 public void shutdown() throws SQLException

Close all available dbConnection

Throws: SQLException: if a database-access error occurs

getNumAllocatedCon

 public int getNumAllocatedCon()

Get the number of connection in the pool of opened dbConnection

Returns:: dbConnection the number of available connections
See Also:: dbConnection

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