Introduction: EJB applications


 

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Based on the EJB specification, enterprise beans are Java components that typically implement the business logic of Java EE applications, as well as access data.

Authentication protocol for EJB security

WAS V7.0 servers support the CSIv2 authentication protocol only. SAS is only supported between V6.0.x and earlier version servers that have been federated in a V7.0 cell.

The option to select between SAS, CSIv2, or both is only available in the administration console when a V6.0.x or earlier release has been federated in a V 7.0 cell.

z/SAS is only supported between V6.0.x and earlier version servers that have been federated in a V7.0 cell. The option to select between z/SAS, CSIv2, or both is only available in the administration console when a V6.0.x or earlier release has been federated in a V 6.1 cell.

To be able to tune the processing of endpoint message-driven beans (MDBs), we need to understand the concepts and considerations for the MDB settings that you configure.

Enterprise beans

An enterprise bean is a Java component that can be combined with other resources to create Java EE applications. There are three types of enterprise beans:

EJBs 3.0 specification

The EJB 3.0 spec that is the foundation of the development and application model for the EJB 3.0 applications.

EJB 3.0 application bindings overview

Before an application that is installed on an appserver can start, all EJB references and resource references defined in the application must be bound to the actual artifacts, such as enterprise beans or resources, defined in the appserver.

EJB 3.0 module packaging overview

Packaging applications that use EJB 3.0 beans is similar to the assembly requirements for J2EE 1.4 applications: components are packaged into modules, and modules are packaged into EAR files. The components and modules both have describing metadata provided in an XML deployment descriptor.

The EJB 3.0 spec supports an additional method to describing metadata and for packaging persistence units.

EJB 3.0 deployment overview

Learn about the EJBs 3.0 deployment model, including to Just-In-Time (JIT) deployment.

Partial column updates for container managed persistence

The WAS implementation of the Container Managed Persistence (CMP) bean method, ejbStore, stored all of the persistent attributes of the CMP bean to the database, even if only a subset of persistent attribute fields were changed. Now we can make partial column updates to CMP beans.

Lightweight local operational mode for entity beans

WAS provides a special operational mode called lightweight local mode, which can improve the performance of entity bean methods. We can decide which entity beans in the application to run in this mode.

Access intent policies

An access intent policy is a named set of properties or access intents that govern data access for EJBs persistence. We can assign policies to an entity bean and to individual methods on an entity bean's home, remote, or local interfaces during assembly.

Access intent service

Access intent is a WAS runtime service that enables you to precisely manage an application's persistence.

EJB modules

An EJB module is used to assemble one or more enterprise beans into a single deployable unit. An EJB module is stored in a standard JAR file.

References

References are logical names used to locate external resources for enterprise applications. References are defined in the application's deployment descriptor file. At deployment, the references are bound to the physical location (global JNDI name) of the resource in the target operational environment.

Sequence grouping for container-managed persistence

After assembling an EJBs module that contains CMP beans, we can prevent certain types of database-related exceptions from occurring during application run time. Using sequence grouping, we can specify the order in which entity beans update relational database tables.

EJB containers

An EJB container provides a run-time environment for enterprise beans within the appserver. The container handles all aspects of an enterprise bean's operation within the appserver and acts as an intermediary between the user-written business logic within the bean and the rest of the appserver environment.

Stateful session bean failover for the EJB container

We can construct applications with the assumption that the applications using stateful session beans are not limited by unexpected server failures. WAS ND v7.0 utilizes the functions of the Data Replication Service (DRS) and Workload Management (WLM) so we can enable stateful session bean failover.

EJB 3.0 deployment overview

Learn about the EJBs 3.0 deployment model, including to Just-In-Time (JIT) deployment.

Message-driven beans - automatic message retrieval

WAS ND v7.0 supports the use of message-driven beans as asynchronous message consumers.

Message-driven beans - listener port components

WAS ND v7.0 support for message-driven beans deployed against listener ports is based on JMS message listeners and the message listener service, and builds on the base support for JMS.




Related information

Learn about EJB applications