org.apache.avalon.excalibur.datasource.cluster

Class DefaultIndexedDataSourceCluster

java.lang.Object

org.apache.avalon.framework.logger.AbstractLogEnabled

org.apache.avalon.excalibur.datasource.cluster.AbstractDataSourceCluster

org.apache.avalon.excalibur.datasource.cluster.DefaultIndexedDataSourceCluster

All Implemented Interfaces:

IndexedDataSourceCluster, DataSourceComponent, org.apache.avalon.framework.activity.Disposable, org.apache.avalon.framework.activity.Initializable, org.apache.avalon.framework.component.Component, org.apache.avalon.framework.configuration.Configurable, org.apache.avalon.framework.logger.LogEnabled, org.apache.avalon.framework.service.Serviceable, org.apache.avalon.framework.thread.ThreadSafe

public class DefaultIndexedDataSourceCluster
extends AbstractDataSourceCluster
implements IndexedDataSourceCluster

The DefaultIndexedDataSourceCluster requires that the user implement their own method of selecting which DataSource in the cluster to use for each connection request. Calls to getConnection() will throw an exception. Components which make use of this class must call the getConnectionForIndex(int index) method instead.

The Configuration for a 2 database cluster is like this:

   <datasources>
     <indexed-cluster name="mydb-cluster" size="2">
       <dbpool index="0">mydb-0</dbpool>
       <dbpool index="1">mydb-1</dbpool>
     </indexed-cluster>
   </datasources>
   <cluster-datasources>
     <jdbc name="mydb-0">
       <pool-controller min="1" max="10"/>
       <auto-commit>true</auto-commit>
       <driver>com.database.jdbc.JdbcDriver</driver>
       <dburl>jdbc:driver://host0/mydb</dburl>
       <user>username</user>
       <password>password</password>
     </jdbc>
     <jdbc name="mydb-1">
       <pool-controller min="1" max="10"/>
       <auto-commit>true</auto-commit>
       <driver>com.database.jdbc.JdbcDriver</driver>
       <dburl>jdbc:driver://host1/mydb</dburl>
       <user>username</user>
       <password>password</password>
     </jdbc>
   </cluster-datasources>
 

With the following roles declaration:

   <role name="org.apache.avalon.excalibur.datasource.DataSourceComponentSelector"
     shorthand="datasources"
     default-class="org.apache.avalon.excalibur.component.ExcaliburComponentSelector">
     <hint shorthand="jdbc" class="org.apache.avalon.excalibur.datasource.JdbcDataSource"/>
     <hint shorthand="j2ee" class="org.apache.avalon.excalibur.datasource.J2eeDataSource"/>
     <hint shorthand="indexed-cluster"
       class="org.apache.avalon.excalibur.datasource.cluster.DefaultIndexedDataSourceCluster"/>
   </role>
   <role name="org.apache.avalon.excalibur.datasource.DataSourceComponentClusterSelector"
       shorthand="cluster-datasources"
       default-class="org.apache.avalon.excalibur.component.ExcaliburComponentSelector">
     <hint shorthand="jdbc" class="org.apache.avalon.excalibur.datasource.JdbcDataSource"/>
     <hint shorthand="j2ee" class="org.apache.avalon.excalibur.datasource.J2eeDataSource"/>
   </role>
 

An indexed-cluster definition enforces that the configuration specify a size. This size must equal the number of datasources referenced as being members of the cluster. Any datasource can be a member of the cluster.

The indexed-cluster can be obtained in the same manner as a non-clustered datasource. The only difference is in how it is used. The IndexedDataSourceCluster requires that the caller specify the index of the cluster member to use when requesting a connection.

The following code demonstrates a change that can be made to database enabled components so that they will be able to work with both IndexedDataSourceCluster DataSources and regular DataSources.

old:

   Connection connection = m_dataSource.getConnection();
 

new:

   Connection connection;
   if ( m_dataSource instanceof IndexedDataSourceCluster )
   {
     connection = ((IndexedDataSourceCluster)m_dataSource).getConnectionForIndex( index );
   }
   else
   {
     connection = m_dataSource.getConnection();
   }
 

Since:

4.1

Version:

CVS $Revision: 1.4 $ $Date: 2004/02/28 11:47:20 $

Author:

Avalon Development Team

Field Summary

Fields inherited from class org.apache.avalon.excalibur.datasource.cluster.AbstractDataSourceCluster

m_size

Fields inherited from interface org.apache.avalon.excalibur.datasource.cluster.IndexedDataSourceCluster

ROLE

Constructor Summary

Constructors

Constructor and Description
DefaultIndexedDataSourceCluster()

Method Summary

Methods

Modifier and Type	Method and Description
java.sql.Connection	getConnection() Not supported in this component.

Methods inherited from class org.apache.avalon.excalibur.datasource.cluster.AbstractDataSourceCluster

configure, dispose, getClusterSize, getConnectionForIndex, initialize, service

Methods inherited from class org.apache.avalon.framework.logger.AbstractLogEnabled

enableLogging, getLogger, setupLogger, setupLogger, setupLogger

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.avalon.excalibur.datasource.cluster.IndexedDataSourceCluster

getClusterSize, getConnectionForIndex

Methods inherited from interface org.apache.avalon.framework.configuration.Configurable

configure

Constructor Detail

DefaultIndexedDataSourceCluster

public DefaultIndexedDataSourceCluster()

Method Detail

getConnection

public java.sql.Connection getConnection()
                                  throws java.sql.SQLException

Not supported in this component. Will throw a NoValidConnectionException.

Specified by:

getConnection in interface DataSourceComponent

Returns:

Connection a valid connection for you to use

Throws:

NoValidConnectionException - when there is no valid Connection wrapper available in the classloader.

NoAvailableConnectionException - when there are no more available Connections in the pool.

java.sql.SQLException