Rescuing a legacy as a first Eiffel project

FSTINT is a legacy computer application which has been in use nearly 20 years. FSTINT interprets encoded models of finite state transducers (FSTs). The combination of FSTINT and a particular FST model typically is used as a 3GL source code pre-processor to generate native calls to utility products such as forms and message managers. Because FSTINT is written in assembler language, it is not portable from its original platform. Eiffel was chosen to develop a platform independent version of FSTINT, with the goal of utilizing the same source files for FST models as the legacy system used. The new version of FSTINT was produced by a one-person development team and as a three billion dollar company´s first Eiffel project. In this experience paper the product itself is described, as well as the approach to an object oriented, Eiffel based solution. The author´s perceptions, both technical and cultural and both positive and negative, are documented as well