Business applications running on IBM mainframes and minicomputers continue to representative an enormous share of IT assets and business processes. These legacy applications remain in use because they still serve critical business functions well. Windows desktop computers running 3270 or 5250 emulation software typically provide the client and presentation layer.
The following figure shows integration based on the user interface, which represents the most primitive approach, used primarily with older legacy applications. For some host-based applications running on mainframes and minicomputers, the source code and development resources is no longer available. So the only point where integration can occur is through the user interface. Screen scraping is the only alternative for some older host applications until they are replaced.
Integration based on the User Interface