Enterprise JavaBeans (EJBs)

Enterprise JavaBeans (EJBs) are the workhorses of the applications. If servlets act as the central dispatcher for the application and handle presentation logic, EJBs do the bulk of the application's actual data and rules processing. EJBs do not provide presentation or visible user interface services. EJBs enable the partitioning of business logic, rules, and objects into discrete, modular, and scalable units. Each EJB encapsulates one or more application tasks or application objects, including data structures and the methods that operate on them. Typically, they also take parameters and send back return values.

EJBs always work within the context of a container, which serves as a link between the EJBs and the server that hosts them. NAS developers need not worry about the container for the EJBs. The NAS software environment provides the container for the EJBs. This container provides all the standard container services denoted by the Sun EJB specification. It also provides other services that are specific to NAS.

In fact, the container can handle all remote access, security, concurrency, transaction control, and database access. Because the actual implementation details are part of the container, and there is a standard, prescribed interface between a container and its EJBs, the bean developer is freed from having to know or handle platform-specific implementation details. Instead, the enterprise bean developer can create generic, task-focused EJBs that can be used with any vendor's products that support the EJB standard.

http://java.sun.com/products/ejb/