CSC/ECE 517 Fall 2010/ch6 6i ak
Business applications have evolved gradually over time from the ages of monolithic architectures, witnessing a slow transition to the Client-server architecture and then to multitier-client server architecture and culminating with Distributed systems and it still continues to evolve....So at any point in time, there would be different systems involving different architecture and should still be able to communicate with each other. There is also a possibility that some of the systems still follow the monolithic architecture, while others use an architecture of recent times. Sabre, Amadeus, Singapore Airlines, American Express, NYPD run on a Mainframe system, that runs on a technology that dates us back to the 1970s![1]
references
http://en.wikipedia.org/wiki/Transaction_Processing_Facility