OMG was created in 1989 to develop, adopt, and promote standards for the development and deployment of applications in distributed heterogeneous environments [Vin97], [VD98]. OMG is a large consortium with more than 800 companies trying to reach a consensus on an appropriate component model and services for developing component-based distributed applications ( OMG is the world's largest computer consortium and is a nonprofit organization that started initially with eight members: 3Com, American Airlines, Canon, Data General, Hewlett-Packard, Philips Telecommunications N.V., Sun Microsystems, and Unisys [VD98]. OMG does not develop any technology per se, nor does it advertise any product of its members. OMG's goal is to promote the object-oriented approach to software engineering and create a general architectural framework for developing component-based distributed applications based on the interface spécifications for objects of the application. OMG works to provide standards for building component-based applications and encourages its members to follow these standards.

The component-based approach is the heart of OMG's Object Management Architecture (OMA). OMA defines the specifications for the underlying distributed architecture and the way components dialog with each other in a distributed environment. OMA is the general framework that embraces all technologies adopted by OMG [VD98].

The Common Object Request Broker Architecture (CORBA) is one the most important middleware project undertaken by the software industry. It is OMG's response to the challenging problem of building communication bridges between isolated islands developed in different programming languages and computing platforms. CORBA enables natural interoperability, regardless of platform, operating system, programming language, and even of network hardware and software. CORBA defines a mandatory TCP/IP-based protocol for interoperability over the Internet and most intranets. CORBA

clients can run on a large variety of computers, from hand-held wireless palmtops or pagers to desktop machines or mainframes. CORBA servers can also run on all these machine types. The specification standardizes complex resource management and fault tolerance for large, reliable server-side applications. There are also specialized versions of CORBA for real-time and small embedded servers. There is strong support for CORBA on the application side by the OMG, a collection of standardized objects performing functions, including the key enterprise-required services for transaction handling and security. CORBA goes beyond this to define standard objects and frameworks in business domains, such as finance, insurance, manufacturing, the health sector, and more. CORBA is supported by UML that is OMG's standard for Object-Oriented Analysis and Design.

CORBA is composed of three parts: A set of interfaces that can be invoked by users, the object request broker (ORB), and a set of object adaptors [Szy99].

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