Data sources

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

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. WebSphere® Application Server requires JDBC providers to implement one or both of the following data source interfaces. These interfaces enable the application to run in a single-phase or two-phase transaction protocol.

• ConnectionPoolDataSource - a data source that supports application participation in local and global transactions, excepting two-phase commit transactions. 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.
  Note: A connection pool data source does support two-phase commit transactions in these cases:

  • the data source is making use of Last participant support. Last participant support enables a single one-phase commit resource to participate in a global transaction with one or more two-phase commit resources.
  • the JDBC provider is DB2® for z/OS® Local JDBC provider (RRS).

  For more information, see the topic about using one-phase and two-phase commit resources in the same transaction.
• XADataSource - a data source that supports application participation in any single-phase or two-phase transaction environment. When this data source is involved in a global transaction, the product transaction manager provides transaction recovery.

Prior to version 5.0 of the application server, the function of data access was provided by a single connection manager (CM) architecture. This connection manager architecture remains available to support Java 2 Platform, Enterprise Edition (J2EE) 1.2 applications, but another connection manager architecture is provided, based on the JCA architecture supporting the J2EE 1.3 application style, J2EE 1.4 and Java EE applications.

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