Session Beans INFORMATICS ENGINEERING – UNIVERSITY OF BRAWIJAYA Eriq Muhammad Adams J

Agenda  What is Session Beans ?  When do you use Session Beans ?  Rich Client Applications  Web Based Applications  Local vs Remote Interface  Stateless vs Stateful Bean  Stateless Bean Lifecycle  Stateful Bean Lifecycle  Session Beans Practice  Demo

What is EJB Session Beans ?  Java components that run in EJB Containers / JEE Application Servers  Java components typically used to model use cases  Hold business logic  There are two types :  Stateless : This type of bean does not maintain any conversational state on behalf of a client application.  Stateful: This type of bean maintains state, and a particular instance of the bean is associated with a specific client request. Stateful beans can be seen as extensions to client programs that are running on the server.

When do you use Session Beans ?  If you want to :  write business logic  maintain a client ‘s conversation state  model back-end processes  You can use it in :  2-tier Applications  3-tier Applications  Rich Client Applications  Web-based Applications

Rich Client Applications

Web-based Applications

Local vs Remote Interface A web client using local interfaces of session beans

Local vs Remote Interface (cont.) A rich client using remote interfaces of session beans

Stateless vs Stateful Bean Stateless Session BeansStateful Session Beans

Stateless vs Stateful Bean (cont.)

Stateless Lifecycle

Stateful Bean Lifecycle

Session Beans Best Practices  Choose your bean type carefully. Mostly use Stateless, if you have web-tier client use HttpSession instead.  Carefully examine interface types for session beans. If the client will always be used within the same JVM as the bean, then use a local interface.  Inject carefully. Make sure you don’t inject a stateful session bean into a stateless session bean or servlet.  Separate crosscutting concerns such as logging and auditing using business interceptors.  Closely examine what kind of data you are storing in the conversation state.  Try to use small, primitive instance variables in a stateful bean whenever possible as opposed to large nested composite objects.  Don’t forget to define remove methods in a stateful session bean.  Tune passivation and timeout configurations to find the optimal values for your application.

Demo  Demo in SessionBeansDemo.zip 

References  EJB In Action, Manning  Beginning EJB 3 Application Development, Apress