EJB 3.0

[Características]
- Encapsulation of environmental dependencies and JNDI access through the use of annotations, dependency injection mechanisms, and simple lookup mechanisms.

- Elimination of the requirement for EJB component interfaces for session beans. The required business interface for a session bean can be a plain Java interface rather than an EJBObject, EJBLocalObject, or java.rmi.Remote interface.

- Elimination of the requirement for home interfaces for session beans.

- An interceptor facility for session beans and message-driven beans.

- Reduction of the requirements for usage of checked exceptions.

- Elimination of the requirement for the implementation of callback interfaces.

[Papéis EJB - J2EE]
- Enterprise Bean Provider:
The Enterprise Bean Provider is the producer of enterprise beans.

- Application Assembler:
The Application Assembler is a domain expert who composes applications that use enterprise beans. Although the Assembler must be familiar with the functionality provided by the enterprise bean’s client-view interfaces, he does not need to have any knowledge of the enterprise bean’s implementation.

- Deployer:
The Deployer is an expert at a specific operational environment and is responsible for the deployment of enterprise beans. For example, the Deployer is responsible for mapping the security roles defined by the Bean Provider or Application Assembler to the user groups and accounts that exist in the operational
environment in which the enterprise beans are deployed.

- System Administrator:
The System Administrator is responsible for the configuration and administration of the enterprise’s computing and networking infrastructure that includes the EJB server and container. The System Administrator is also responsible for overseeing the well-being of the deployed enterprise beans applications at runtime.

- EJB Server Provider:
The EJB Server Provider is a specialist in the area of distributed transaction management, distributed objects, and other lower-level system-level services. A typical EJB Server Provider is an OS vendor, middleware vendor, or database vendor.

- EJB Container Provider:
The expertise of the Container Provider is system-level programming, possibly combined with some application-domain expertise. The focus of a Container Provider is on the development of a scalable, secure, transaction-enabled container that is integrated with an EJB server. The Container Provider insulates the enterprise bean from the specifics of an underlying EJB server by providing a simple, standard API between the enterprise bean and the container. This API is the Enterprise JavaBeans component contract. The Container Provider typically provides support for versioning the installed enterprise bean components. For example, the Container Provider may allow enterprise bean classes to be upgraded without invalidating existing clients or losing existing enterprise bean objects.

- Persistence Provider:
The expertise of the Persistence Provider is in object/relational mapping, query processing, and caching. The focus of the Persistence Provider is on the development of a scalable, transaction-enabled runtime environment for the management of persistence.