RE: Why does EJB needs two interfaces(Home and Remote Interface)
The client cant deal with the bean diirectly. All the client calls are intercepted by the container. This layer of interception is EJBObject. For the container to create EJBObjects , it should know all the business methods of the bean. So the bean provider will have to write a REMOTE INTERFACE with all the beans business methods. In distributed envt,we will not know where the EJBObjects are located. So we need HomeObjects which implement the Home Interface to get a handle for EJBObjects
RE: Why does EJB needs two interfaces(Home and Remote Interface)
An indirection can solve almost all the problems in computer science. This is also such a type of problem. In case of only one interface (as in the case of RMI), the client has to maintain all the references of the EJB objects (i.e. remote objects) which will be cumbersome in large distributed environment and requires lot of overhead. Hence to look up the references, a home interface is introduced as an indirection. Each and every client first looks up for the remote object reference in the JNDI tree and then gets the reference. The EJBObject reference is returned to the requesting clilent. And also, in J2EE, we can use the EJBObject reference once created to serve n number of clients.
RE: Why does EJB needs two interfaces(Home and Remote ...
Actually Home interface are used as a Factory to get Bean reference. However since the Bean class/object is not available to the client it uses the remote interface to hold the bean reference
RE: Why does EJB needs two interfaces(Home and Remote ...
I would say that the main reason is because there is a clear division of roles and responsibilities between the home and remote interfaces of an EJB.
The home interface allows the client to communicate with the container which is responsible for creating, finding and removing beans. Whereas the remote interface is the way to communicate with the bean that will allow to remotely access to all its methods. Therefore you need two interfaces for two different purposes i.e) home interface to communicate with the container and remote interface to communicate with the bean.
