J2EE Interview questions and answers

71. What is durable subscription 

In a JMS publish/subscribe messaging system, a
subscription that continues to exist whether or not
there is a current active subscriber object. If there
is no active subscriber, the JMS provider retains the
subscription's messages until they are received by the
subscription or until they expire. 

72. What is EAR file 

Enterprise Archive file. A JAR archive that contains a
J2EE application.


73. What is ebXML 

Electronic Business XML. A group of specifications
designed to enable enterprises to conduct business
through the exchange of XML-based messages. It is
sponsored by OASIS and the United Nations Centre for
the Facilitation of Procedures and Practices in
Administration, Commerce and Transport (U.N./CEFACT). 

74. What is EJB 

Enterprise JavaBeans. 

75. What is EJB container 

A container that implements the EJB component contract
of the J2EE architecture. This contract specifies a
runtime environment for enterprise beans that includes
security, concurrency, life-cycle management,
transactions, deployment, naming, and other services.
An EJB container is provided by an EJB or J2EE server.


76. What is EJB container provider 

A vendor that supplies an EJB container. 


77. What is EJB context 

A vendor that supplies an EJB container. An object
that allows an enterprise bean to invoke services
provided by the container and to obtain the
information about the caller of a client-invoked
method. 

78. What is EJB home object 

An object that provides the life-cycle operations
(create, remove, find) for an enterprise bean. The
class for the EJB home object is generated by the
container's deployment tools. The EJB home object
implements the enterprise bean's home interface. The
client references an EJB home object to perform
life-cycle operations on an EJB object. The client
uses JNDI to locate an EJB home object


79. What is EJB JAR file 

A JAR archive that contains an EJB module. 

80. What is EJB module 

A deployable unit that consists of one or more
enterprise beans and an EJB deployment descriptor.