Legacy Object Framework

The Legacy Object Framework (LOF) was a system I designed and implemented while at the company Yrrid Incorporated during the 1990s. LOF was a system whereby one could model the screen contents of a terminal based application, such as IBM 3270, and script interactions such that a modernized API could be built which interacted with the terminal based application. This all allowed web front ends to be built on an existing system without a rewrite. The LOF implementation involved headless terminal emulation running on a server, distributed load balancing, a screen modeling application, scripting environment, API generation and client/server tools for interaction with terminal emulation through the scripted control. This allowed companies to build web or desktop based programs “on top of” existing terminal based systems. A variety of companies used this system in the 1990s to build web interfaces on top of legacy systems.

LOF was implemented for OpenStep and ran on Windows primarily, we had runtimes available for Solaris, HP-UX and NextStep as well.

The system was documented by my co-workers in a Communications of the ACM here:


I was not involved in the writing of the paper. I had designed and implemented the core terminal emulation product, the LOF modeling application, the scripting system and execution environment. Our sales engineering team built client applications using web based technologies and wrote the paper.