Enterprise Bean (EJB) programming tutorials

Enterprise Beans Tutorial

Home| Forums | Join Google Group | Join Yahoo Group | Jobs

Earn Money
Trading Forex Online
  Paramount Airways
  Free Data Recovery
Cargo
Job Portal
  HSBC Investment
Management
Cheap Web Hosting
  Make Trip
  Cheap Air Travel
Leisure Hotel
  Free Air Travel
  Mutual Fund Informations
Cheapest Cellular Plan
Free Sexy Indians
  Call Center Software
  Hot Indian

Enterprise Beans Tutorial

1 Enterprise Beans Enterprise beans are server components written in the Java programming language.
Enterprise beans contain the business logic for your application. Session Beans A session bean represents a client in the J2EE server.
A session bean converses with the client, and can be thought of as an extension of the client.
Each session bean can have only one client.
When the client terminates, its corresponding session bean also terminates . Therefore, a session bean is transient, or non-persistent . Entity Beans An entity bean represents a business object in a persistent storage mechanism such as a database
might be stored as a row in the customer table of a relational database.
An entity bean's information does not have to be stored in a relational database. It could be stored in an object database, a legacy application, a file, or some other storage mechanism. The persistence of an entity bean can be managed by either the entity bean itself, or by the EJB container.
Bean-managed persistence requires you to write the data access code in the Bean.
Container-managed persistence means that the EJB container handles the data access calls automatically. Comparing Session and Entity Beans Session Bean Entity Bean Purpose Performs a task for a client. Represents a business entity object
that exists in persistent storage. Shared
Access May have one client. May be shared by multiple clients. Persistence Not persistent. When the client
terminates its session bean is no
longer available. Persistent. Even when the EJB
container terminates, the entity state
remains in a database. Java Beans TM Components and Enterprise Beans · JavaBeans components and enterprise beans are not the same. Although both components are written in
the Java programming language, they are not interchangeable. · JavaBeans components define a convention for making a Java class instance customizable by design
tools, allowing the tools to link these customized objects via events. · Enterprise beans implement multi-user, transactional services. Programming Restrictions for Enterprise Beans To avoid conflicts with the services provided by container,, enterprise beans are restricted from performing
certain operations: · Managing or synchronizing threads · Accessing files or directories with the java.io package