Inverse Wrappers for Legacy Information Systems Migration

The paper studies some problems that arise when a technology change induces the migration of a data-centered application. In particular, it addresses the difficult problem of migrating application programs from a legacy data manager, such as a COBOL file system, to a modern DBMS, such as a relational database management system. The approach suggested in this paper relies on the concept of inverse wrappers, that is, wrappers that simulate the legacy API on top of the new database. This architecture allows (1) the design of a fully normalized database rid of the anomalies of the legacy data, (2) future programs to be developed on a sound basis and (3) legacy programs to work on the new database with minimum transformation, and therefore at low cost. The paper describes the components of this architecture, a methodology to design them and a CASE tool that automates their generation.