In this post, we continue our discussion on Java EJB.
The bean class methods must be declared as public and must not be final or static. The throws clause may define arbitrary application exceptions. and the bean class must not define the finalize() method.
The beans can be specified as stateless, stateful and message-driven. Injecting resource dependency into a variable or setter method is done by the EJB container.   PersistenceContext can also be injected using the data type EntityManager and the corresponding imports. Then the entity can be found using the EntityManager object
Person p = em.find(Person.class, 10);
New entities can be added as em.persist(p);
Specifying interceptors are optional. The Interceptors annotation is used to annotate the interceptor class with the bean class. The method in the interceptor class annotated with the AroundInvoke annotation then becomes the interceptor method for the bean class.
The PostConstruct and PreDestroy annotations are for notifications immediately after the dependency injection and before first business method  and for releasing resources respectively.
EJB Access can be secured with the DeclareRoles, RolesAllowed, DenyAll, PermitAll and RunAs annotations.
Once the Java source code is compiled, deployment descriptors can be created or edited.
Exception handling can be done by try catch blocks and the methods can mention the exceptions
There are several things to consider for a good java EJB program. Sime of these are:
Modular code
Design patterns
Layering
Performance
Security