The Common Object Request Broker Architecture (CORBA) and its Notification Service

Abstract

The distributed and heterogeneous natures of todays computing systems require a middleware infrastructure capable of supporting a three-tier computing architecture. Business logic can be built, or existing applications encapsulated, into middle tier components that interact with end users via standard interfaces such as web browsers and standard GUI desktops, and back-end data repositories.The Common Object Request Broker Architecture, or CORBA for short, is a specification produced by the Object Management Group (OMG) that addresses interoperability in distributed heterogeneous environments. The CORBA standard represents industry consensus from more than 800 companies. It is an open, vendor-independent architecture and infrastructure that computer applications use to work together over networks. Using the standard protocol IIOP, a CORBA-based program from any vendor, on almost any computer, operating system, programming language, and network, can interoperate with a CORBA-based program from the same or another vendor, on almost any other computer, operating system, programing language, and network. It defines an Object Request Broker (ORB) for transparent invocation of remote objects, as well as supporting system level Object Services and higher level Common Facilities. CORBA assumes a heterogeneous environment in which objects implemented in different languages on different platforms can inter-operate. There are many implementations of the CORBA standard, some of them in the form of commercial products that have demonstrated strong market acceptance.This paper presents CORBA in a simple and easy to understand language. It assumes only a basic familiarity with computers and programming languages. Object Services is one of the five integral components of the Object Management Architecture (OMA)—which forms the heart of CORBA. There are several Object Services like Collection Service, Concurrency Service, Event Service, Naminty Service, Query Service, Notification Service, Time Service, Transaction Service, etc. This paper presents in a very simplified form, one of these services called as CORBA notification Service. It compares and contrasts it with the Event Service and discusses the deficiencies in Event Service and how the Notification Service resolves them. The applicability of the Notification Service in real-life scenarios is also discussed.