Java Interview Questions

POA stands for Portable Object Adapeter.It is CORBA 3.0 technology that makes the server side applications portabale across multi vendor ORBs(i.e.ORB’s developed by different companies like Visigenic or Orbix Wev etc.). We can replace BOA deals with transparent activation activation of objects POA can support both IDL-generated static skeletons and DSI,like BOA.

CORBA standard describes a number of object adapters, whose primary purpsoe is to interface an object’s implementation with its ORB.OMG provides 3 sample Object Adapters. They are Basic OBject Adapter(BOA), Libary Object Adapter and Object-Oriented Database Adapter(sueful for accessing objects in persistent storage). BOA provides CORBA objects with a common set of methods for accessing ORB functions. These funcations range from user authentication to object activation to object persistence. According to CORBA specification, the BOA should be available in every ORB implementation and will occur with most of the CORBA available products.

The central concept of CORBA’s architecture is ORB. The ORB got some responsibilities.

They are as follows:

1. If an object reference is given by a client, the ORB locates the corresponding object implementation on the other side(the server) on behalf of the client.

2. When the server is located, the ORB ensures the server to receive the request.

3. The ORB on client side accepts the parameters and marshals the methos’s parameters to the network.

4.ORB on the server sidfe unmarshals the parameters from the nerwork and sends them top server

5.If the return parameters exits, they are either marshalled/unmarshalled in the same manner.

6.The ORB makes a platform - inpendent type of date. The parameters are on the-fly between varying machine formats as theuy are marshalled and unmarshalled.