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A large Mutual Funds Processing Company wanted to put it's accounts online so shareholders to be able to view their accounts, and make trades.
This application was "cutting-edge' for it's day (circa 1999). It used a Screen Scraper middleware from Syntellect (coded in REXX) to communicate directly with custom VSAM screens running in CICS. From there the data was transferred to a Netscape Iplanet webserver via CGI calls which rendered custom tags much like modern-day Cold-Fusion tags.
From there Client-Side Javascript takes over to make asynchronous calls via a hidden data-island back throug the middleware to the mainframe.
This programming approach has come to be called AJAX in the last year, of course at the time I did it, it had no such name.
See the demo