Introduction: EJB applications
Explore the key concepts pertaining to EJB applications. Based on the EJB specification, enterprise beans are Java components that typically implement the business logic of Java 2 Platform, Enterprise Edition (J2EE) applications as well as access data.
- Enterprise beans
- An enterprise bean is a Java component that can be combined with other resources to create J2EE applications. There are three types of enterprise beans: entity beans, session beans, and message-driven beans.
- Partial column updates for container managed persistence
- Previously, the WAS implementation of the Container Managed Persistence 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.
- Lightweight local operational mode for entity beans
- WebSphere Application Server 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 your application to run in this mode.
- Access intent policies
- An access intent policy is a named set of properties (access intents) that governs data access for Enterprise JavaBeans 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. We can set access intents only within EJB V2.x-compliant modules for entity beans with CMP Version 2.x.
- Access intent service
- Access intent is a WAS runtime service that enables you to more 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 Java archive (JAR) file.
- Sequence grouping for container-managed persistence
- After assembling an Enterprise JavaBeans 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 Enterprise JavaBeans container provides a run-time environment for enterprise beans within the application server. The container handles all aspects of an enterprise bean's operation within the application server and acts as an intermediary between the user-written business logic within the bean and the rest of the application server environment.
- Stateful session bean failover for the EJB container
- WebSphere Application Server v6 enables you to construct applications with the assumption that your applications using stateful session beans are not limited by unexpected server failures. This version of the product utilizes the functions of the Data Replication Service (DRS) and Workload Management (WLM) so we can enable stateful session bean failover.
- Message-driven beans - automatic message retrieval
- WebSphere Application Server supports the use of message-driven beans as asynchronous message consumers.
- Message-driven beans - listener port components
- The WAS support for message-driven beans deployed against listener ports is based on Java Message Service (JMS) message listeners and the message listener service, and builds on the base support for JMS.
Related information
EJB applications