OCEJBCD - 2- Implementing Session Beans

OCEJBCD (SCBCD) - 1Z0-895 - Enterprise JavaBeans Developer Certification

2.1. Examine session Beans

A session bean encapsulates business logic that can be invoked programmatically by a client over local, remote, or web service client views. 

What is a session bean?

2.2. Identify the three types of session beans

• Stateless
• they can support multiple clients
• does not mantain conversational state with the client.
• Stateful
• Mantains conversational state with the client.
• Relationship 1:1 with client.
• Singleton 
• new in javaEE6
• is instantiated once per application and exists for the lifecycle of the application (one per application).
• A single enterprise bean needs to be accessed by multiple threads concurrently

2.3. Choose the correct session bean type given a business constraint

• Session stateless - to implement a web service. Transaction-processing applications, which are executed using a procedure call.
• Session stateful - GUI client (filling fields in a GUI needs conversational state)
• Singleton- to implement web service endpoints

2.4. Create session beans package and deploy session beans

The javabeans configuration can be defined with annotations or using an xml deployment descriptor located in :
META-INF/ejb-jar.xml

OCEJBCD (SCBCD) - 1Z0-895 - Enterprise JavaBeans Developer Certification