Introduction: Data access resources

Explore the key concepts pertaining to applications that access data. Various enterprise information systems (EIS) use different methods for storing data. These backend data stores might be relational databases, procedural transaction programs, or object-oriented databases.

Partial column updates for container managed persistence

Previously, the WebSphere Application Server 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 J2EE Connector Architecture (JCA) connection factory, which provides connectivity to other types of enterprise information systems (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 enterprise information systems (EIS) is based on the J2EE Connector Architecture (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 Java Database Connectivity (JDBC) 2.0 (and later) Extensions specification.

Application performance and entity bean behavior

WebSphere Application Server 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 WebSphere Application Server.

Accessing data using J2EE Connector Architecture connectors

To access data from a J2EE Connector Architecture (JCA) compliant application in WebSphere Application Server, you configure and use resource adapters and connection factories.

Data access with Service DataObjects

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 container-managed persistence (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

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

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