Introduction: Data access resources



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Partial column updates for container managed persistence

Previously, the WAS implementation of the Container Managed Persistence (CMP) bean method ejbStore always stored all of the persistent attributes of the CMP bean to the database, even if only a subset of persistent attribute fields were changed. This needless performance degradation is eliminated in this release of the product.

Resource adapters

A resource adapter is a system-level software driver that a Java application uses to connect to an enterprise information system (EIS). A resource adapter plugs into an application server and provides connectivity between the EIS, the application server, and the enterprise application.

JDBC providers

Installed applications use JDBC providers to interact with relational databases. The JDBC provider object supplies the specific JDBC driver implementation class for access to a specific vendor database. To create a pool of connections to that database, you associate a data source with the JDBC provider. Together, the JDBC provider and the data source objects are functionally equivalent to the J2EE Connector Architecture (JCA) connection factory, which provides connectivity with a non-relational database.

Data sources

Installed applications use a data source to obtain connections to a relational database. A data source is analogous to the JCA connection factory, which provides connectivity to other types of EIS.

Data access beans

Data access beans provide a rich set of features and function, while hiding much of the complexity associated with accessing relational databases. They are Java classes written to the Enterprise JavaBeans specification.

Connection management architecture

The connection management architecture for both relational and procedural access to EIS is based on the JCA specification. The Connection Manager (CM), which pools and manages connections within an application server, is capable of managing connections obtained through both resource adapters (RAs) defined by the JCA specification, and data sources defined by the JDBC 2.0 (and later) Extensions specification.

Application performance and entity bean behavior

WAS allows you to override two behaviors that are required by the EJB specification, because your application might benefit from handling these aspects of bean data management in a slightly different manner.

The benefits of using resource references

Using a resource reference to access your data source or connection factory is required when running WAS.

Accessing data using J2EE Connector Architecture connectors

To access data from a JCA) compliant application in WAS, you configure and use resource adapters and connection factories.

Data access with Service DataObjects, API versions 1.0 and 2.01

The Service DataObjects (SDO) framework is a data-centric, disconnected, XML-integrated, data access mechanism that provides a source-independent result set.

Exceptions pertaining to data access

All enterprise bean CMP beans under the EJB 2.x specification receive a standard EJB exception when an operation fails. JDBC applications receive a standard SQL exception if any JDBC operation fails.

Test connection service

WAS provides a test connection service for testing connections to the data sources that you configure for database access.

Performing platform-specific tasks for JDBC access

Always consult the product documentation for a list of the database brands and versions that are supported by your particular WAS version, edition, and FixPak.

Related information

Data access resources