Data Model Reverse Engineering in Migrating a Legacy System to Java

Central to any legacy migration project is the translation of the data model. Decisions made here will have strong implications to the rest of the translation. Some legacy languages lack a structured data model, relying instead on explicit programmer control of the overlay of variables. In this paper we present our experience inferring a structured data model in such a language as part of a migration of eight million lines of code to Java. We discuss the common idioms of coding that were observed and give an overview of our solution to this problem.