Data sources

 

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Installed applications use a data source to obtain connections to a relational database. A data source is analogous to the J2EE Connector Architecture (JCA) connection factory, which provides connectivity to other types of enterprise information systems.

A data source is associated with a JDBC provider, which supplies the driver implementation classes that are required for JDBC connectivity with your specific vendor database. Application components transact directly with the data source to obtain connection instances to your database. The connection pool that corresponds to each data source provides connection management.

You can create multiple data sources with different settings, and associate them with the same JDBC provider. For example, you might use multiple data sources to access different databases within the same vendor database application. WAS requires JDBC providers to implement one or both of the following data source interfaces, which are defined by Sun Microsystems. These interfaces enable the application to run in a single-phase or two-phase transaction protocol.

ConnectionPoolDataSource Supports local and global transactions, excepting two-phase commit transactions.

Connection pool data sources support two-phase commit transactions in two cases:

When a connection pool data source is involved in a global transaction, transaction recovery is not provided by the transaction manager. The application is responsible for providing the backup recovery process if multiple resource managers are involved.

XADataSource Supports single-phase or two-phase transaction environment. In a global transaction, the WAS transaction manager provides transaction recovery.

In WAS releases prior to version 5.0, the function of data access was provided by a single connection manager (CM) architecture. This connection manager architecture remains available to support J2EE 1.2 applications, but another connection manager architecture is provided, based on the JCA architecture supporting the new J2EE 1.3 application style (also for J2EE 1.4 applications).

These two separate architectures are represented by two types of data sources. To choose the right data source, administrators must understand the nature of their applications, EJB modules, and enterprise beans.

Data source (WAS V4) This data source runs under the original CM architecture. Applications using this data source behave as if they were running in V4.0.
Data source This data source uses the JCA standard architecture to provide support for J2EE version 1.3 and 1.4 applications. It runs under the JCA connection manager and the relational resource adapter.

 

Choice of data source




 

Related concepts

Resource adapters
JDBC providers

 

Related tasks

Access data from application clients
Configure a JDBC provider using the console
Configure a data source using the console
Configure a JDBC provider using scripting
Configure new data sources using scripting
Configure new WAS40 data sources using scripting
Create a JDBC provider and data source using the Java Management Extensions API
Configure data access for application clients using the assembly tool and ACRCT
Create a resource reference using the assembly tool
Assemble data access applications using the assembly tool
Deploy data access applications
Develop data access applications
Configure a JDBC provider for a clustered environment
Migrate applications to use data sources of the current JCA
Configure a JDBC provider and data source