Introduction: Data access resources
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 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 WAS ND V7.
- Java Persistence API (JPA) Architecture
- Data persistence, the ability to maintain data between application executions, is vital to enterprise apps because the required access to relational databases. Applications that are developed for this environment must manage persistence themselves or make use of third-party solutions to handle database updates and retrievals with persistence. JPA provides a mechanism for managing persistence and object-relational mapping and functions for the EJB 3.0 specifications.
- JPA for WAS
- JPA for WAS is built on the Apache OpenJPA open source project.
- Database generated version ID
- JPA for WAS has extended OpenJPA to work with database generated version IDs. These generated version fields (timestamp or token) can be used to efficiently detect changes to a given row.
- Relational resource adapters and JCA
- A resource adapter is a system-level software driver that a Java application uses to connect to an EIS. A resource adapter plugs into an appserver and provides connectivity between the EIS, the appserver, 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 Java Beansspecification.
- 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 appserver, 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.
- Cache instances
- An application uses a cache instance to store, retrieve, and share data objects within the dynamic cache.
- Application performance and entity bean behavior
- WAS allows you to override two behaviors that are required by the EJB specification, because the application might benefit from handling these aspects of bean data management in a slightly different manner.
- The benefits of using resource references
- Use a resource reference to access the data source or connection factory is required when running WAS.
- Connection management architecture
- The connection management architecture for both relational and procedural access to enterprise information systems (EIS) is based on the Java EE Connector Architecture (JCA) specification. The Connection Manager (CM), which pools and manages connections within an appserver, 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.
- 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.
- The appserver for z/OS® allows you to assign a thread identifier as an owner of a connection, when you first obtain the connection. The thread identity function only applies to Java EE JCA resource adapters and Relational Resource Adapter (RRA) wrappered JDBC providers that support the use of thread identity for connection ownership.
- Exceptions pertaining to data access
- All enterprise bean CMP beans under the EJB 2.x spec receive a standard EJB exception when an operation fails. JDBC applications receive a standard SQL exception if any JDBC operation fails.
- J2EE connector security
- The J2EE connector architecture defines a standard architecture for connecting J2EE to heterogeneous EIS. Examples of EIS include ERP, mainframe transaction processing (TP) and database systems.
- Test connection service
- WAS provides a test connection service for testing connections to the data sources that you configure for database access.
Related information
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