http://www.roseindia.net

[amar]

Part 3 of this article describes the deployment process for Enterprise JavaBeans components.

Deployment also uses a special deployment descriptor file, which supports parameters that govern enterprise bean behavior, such as whether a bean requires transactions. This feature of bean deployment supports the EJB goal of declarative, as well as programmatic, specification of bean behavior. Part 3 also contrasts the two primary types of persistence, bean-managed and container-managed, and discusses the relationship of EJB components to CORBA. A simple three-tier EJB application is also presented.

The developer of an EJB component composes the Java source file for the bean, which contains the business logic methods that give the bean its functionality plus an ejbCreate() method. The bean class must also implement the javax.ejb.SessionBean interface or the javax.ejb.
EntityBean interface. The bean developer additionally writes interface files that define extensions to the javax.ejb.EJBHome interface and the javax.ejb.EJBObject interface. The extension of the EJBHome interface, referred to as the bean's home interface, contains a create method, and if the bean is an entity bean, it also contains a finder method. The extension of the EJBObject interface, referred to as the bean's remote interface, specifies the business logic methods that are defined in the bean itself.

for read more information:
http://www-128.ibm.com/developerworks/java/library/j-what-are-ejbs/part3/index.html