Course n°2

Middleware concepts and distributed objects platforms

Re-take :
Middleware touch upon Programing Languages, Operating Systems, Databases, Networks
Heterogeneous, Interoperability, Application Portability
Examples are RPC, RMI, COM, DCE, DCOM, CORBA

CORBA : Common Object Request Broker Architecture
CORBA is a standard specified by the Object Management Group (OMG) which is composed of powerful companies whose objective is to standardize distributed applications.

OMA :Object Model Architecture

The ORB(Object Request Broker) is a layer that enables to inter-connect distributed objects.

Domain Services : Companies agree on an interface adapted to applications of a precise domain..
They use specific APIs for the development of applications Telecom, Medicine, Finance, Insurance ...
Examples : Corbamed, Corbatel

Common Facilities : Common services to a type of application
Examples : Document Management, GUI Toolkit, Editing Facilities ...

Object Services : Common services to all types of application
Examples : Transaction, Security, Naming

IDL (Interface Definition Language)enables to describe the interfaces thanks to concepts.

In Corba, it is necessary to distinguish the IDL stub (client side) from the IDL Skeleton (server side). In other Middlewares, the "proxy" representes the server in the customer-space.
The proxy can be represented as a bridge that manages the communication between two heterogeneous systems.
It is generated by the compiler and is displayed in IDL.