Cracking the Java Coding Interview pdfdrive com

Question Why is ejbFindByPrimaryKey mandatory? (EJB)
Answer An Entity Bean represents persistent data that is stored outside of the
EJB Container/Server. The ejbFindByPrimaryKey is a method used to locate and
load an Entity Bean into the container, similar to a SELECT statement in SQL.
By making this method mandatory, the client programmer can be assured that if
they have the primary key of the Entity Bean, then they can retrieve the bean
without having to create a new bean each time - which would mean creating
duplications of persistent data and break the integrity of EJB.
Question Why do we have a remove method in both EJBHome and
EJBObject? (EJB)
Answer With the EJBHome version of the remove, you are able to delete an
entity bean without first instantiating it (you can provide a PrimaryKey object as
a parameter to the remove method). The home version only works for entity
beans. On the other hand, the Remote interface version works on an entity bean
that you have alreadyinstantiated. In addition, the remote version also works on
session beans (stateless and statefull) to inform the container of your loss of
interest in this bean.

---

interest in this bean.
Question How can I call one EJB from inside of another EJB? (EJB)
Answer EJBs can be clients of other EJBs. It just works. Use JNDI to locate the
Home Interface of the other bean, then acquire an instance reference, and so
forth.
Question What is the difference between a Server, a Container, and a
Connector? (EJB)
Answer An EJB server is an application, usually a product such as BEA
WebLogic, that provides (or should provide) for concurrent client connections
and manages system resources such as threads, processes, memory, database
connections, network connections, etc. An EJB container runs inside (or within)
an EJB server, and provides deployed EJB beans with transaction and security
management, etc. The EJB container insulates an EJB bean from the specifics of
an underlying EJB server by providing a simple, standard API between the EJB
bean and its container.A Connector provides the ability for any Enterprise
Information System (EIS) to plug into any EJB server which supports the
Connector architecture. See http://java.sun.com/j2ee/connector/ for more indepth
information on Connectors.