Bridging boundaries: CORBA in perspective.

peer-reviewed applications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called “bridging technologies” to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes how client applications can invoke operations on server objects using the services of an intermediary known as an Object Request Broker, or ORB. CORBA has already been successfully deployed in a variety of application domains ranging from financial information systems to video-on-demand. While early CORBA adopters were often large commercial enterprises that needed to integrate proprietary back-end applications over diverse operating and hardware systems, CORBA is increasingly finding its way onto the desktop and becoming a serious contender as the technology of choice for the development of Internet-based applications. The standardization of a Java binding for CORBA, supported by products such as Visigenic’s VisiBroker for Java* and Iona Technologies’ OrbixWeb,* allows client applets to invoke server objects across the Internet. Consider the example of a ticket agency that implements a CORBA interface to its services. This agency could then use a Java applet from a Web page to invoke one of its servers and book tickets on behalf of a client. Moreover, Netscape’s incorporation of an ORB into its Communicator* client software means that many users will already have an ORB on their desktop. This article introduces CORBA by describing its key components. We then review the boundaries it helps to bridge. We conclude by comparing CORBA with a number of other bridging technologies available today.