Introduction to Enterprise JavaBeans

Enterprise JavaBeans are small individual components that interact with the rest of Java application architecture.

Enterprise JavaBeans, or EJB, technology provides a distributed component model so that application developers can focus on specific business problems and not have to worry about complex system-level issues. This partitioning allows rapid application development, or RAD, while making the application scalable, robust and secure.

Architecture

Java applications have multiple tiers such as the client tier, Web tier and EJB tier. An enterprise bean contains business objects and business logic. Business objects are components of the business model such as a shopping cart object, an account object or a catalog object. Business logic includes procedures and methods that work on the business objects.

Types

The three kinds of enterprise beans are session beans that are private resources used by the client who creates them, entity beans that represent persistent storage objects and the new message-driven beans that process asynchronous messages delivered via the Java Message Service API.

EJB Containers

EJB containers hold enterprise beans and provide services such as the bean creation, maintenance, destruction, transaction processing and a database or similar persistent storage for the bean. An EJB container is a part of an EJB server that provides naming, directory, email and other services to manage the containers and beans.

References

• "Forte for Java 4"; Sun Microsystems; 2002