Srinivas Jadcharla

• Jul 18th, 2005

 

The EJB container provides services to EJB components. The services include transaction, naming, and persistence support.  
 
Transaction support An EJB container must support transactions. EJB specifications provide an approach to transaction management called declarative transaction management. In declarative transaction management, you specify the type of transaction support required by your EJB component. When the bean is deployed, the container provides the necessary transaction support.  
 
 
Persistence support An EJB container can provide support for persistence of EJB components. An EJB component is persistent if it is capable of saving and retrieving its state. A persistent EJB component saves its state to some type of persistent storage (usually a file or a database). With persistence, an EJB component does not have to be re-created with each use.  
 
 
An EJB component can manage its own persistence (by means of the logic you provide in the bean) or delegate persistence services to the EJB container. Container-managed persistence means that the data appears as member data and the container performs all data retrieval and storage operations for the EJB component. See Chapter 27, "Creating Entity Components" for more information.  
 
Naming support An EJB container must provide an implementation of Java Naming and Directory Interface (JNDI) API to provide naming services for EJB clients and components. Naming services provide:  
 
Location transparency Clients can instantiate components by name, and do not need to know the details about the server hosting the component.  
Deployment flexibility Beginning in EJB version 1.1, EJB components can be configured with naming aliases for components and resources such as databases, JavaMail sessions, and JMS message queues. Using aliases simplifies the procedure to deploy the component on a server where the accessed components and resources use different JNDI names.