Explain CORBA architecture briefly.

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  ARCHITECTURE OF CORBA

The major components that make up the CORBA architecture include the: Interface Definition Language (IDL), Object Request Broker (ORB), The Portable Object Adaptor (POA), Naming Service, and Inter-ORB Protocol (IIOP).


Interface Definition languages: CORBA uses the concept of an interface Definition language to implement the services. IDL is a neutral programming language method of defining how a service is implemented. The syntax of this language is independent of any programming language. IDL is used to define an interface, which describes the methods that are available and the parameters that are required when a call is made for a remote object.

Object Request Broker (ORB): The foundation of CORBA architecture is based on the Object Request Broker (ORB). The ORB is prime mechanism that acts as a middleware between the client and the server. It provides a heterogeneous environment in which a client can remotely communicate with the server irrespective of the hardware, the operating systems, and the software development language used. The ORB helps to establish connection with remote server. When a client wants to use the services of a server, it first needs reference to the object that is providing the service. Here, the ORB plays its role; the ORB resolves the client request for the object reference on behalf of the client and thereby enables the client and the server to establish the connectivity.

Portable Object Adaptor (POA): The POA connects the server object implementation to the ORB. It extends the functionality of the ORB and some its services include: activation and deactivation of the object implementations, generation and management of object references, mapping of object references to their implementations, and dispatching of client requests to server objects through a skeleton.

Naming Service: Defines how CORBA objects can be looked up by a name. It is a Common Object Service (COS) and allows an object to be published using a symbolic name and allows clients to obtain references to the object using a standard API. The CORBA naming service provides a naming structure for remote objects.

Internet Inter-ORB protocol (IIOP): The CORBA standard includes specifications for inter-ORB communication protocols that transmit object requests between various ORBs running on the network. The protocols are independent of the particular ORB implementations running at either end. An ORB implemented in Java can talk to an ORB implemented in C, as long as they are both compliant with the CORBA standard. The inter-ORB protocol delivers messages between two ORBs. These messages might be method requests, return values, error messages etc. The inter-ORB protocol (IIOP) also deals with differences between two ORB implementations. If you want two ORBs to talk, just make sure they both speak the same inter-ORB protocol (IIOP). The Inter-ORB Protocol (IIOP) is based on TCP/IP and so is extensively used on the Internet.

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