Java Beans Questions et reponses d'entretien
Question 1. What is EJB server?
Software that provides services to an EJB container. For example, an EJB container typically relies on a transaction manager that is part of the EJBserver to perform the two-phase commit across all the participating resource managers. The J2EE architecture assumes that an EJB container is hosted by an EJBserver from the same vendor, so it does not specify the contract between these two entities. An EJB server can host one or more EJB containers.
Question 2. What is entity bean?
An enterprise bean that represents persistent data maintained in a database. An entity bean can manage its own persistence or can delegate this function to its container. An entity bean is identified by a primary key. If the container in which an entity bean is hosted crashes, the entity bean, its primary key, and any remote references survive the crash.
Question 3. What is EJB object?
An object whose class implements the enterprise bean's remote interface. A client never references an enterprise bean instance directly. A client always references an EJB object. The class of an EJB object is generated by a container's deployment tools.
Question 4. 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.
Question 5. 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.
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