Integration of Highly Fragmented Legacy Information Systems Through Object Modeling and Layered Wrappers

The Cooperative Architecture, defined in the context of the Unitary Network of the Italian Public Administration, is perhaps the most ambitious project undertaken by the Italian Authority for Information Systems in Public Administration (A.I.P.A.). The goal of the architecture is to facilitate the interoperation at the application level of the autonomous and heterogeneous information systems of the different administrations. The main principle dictated by the architecture suggests that each administration should be able to both export its own services and, in turn, to integrate other administrations exported services into its own applications. The main problem in the practical realization of the architecture is the pervasive presence of legacy systems and applications throughout the administrations. Because these closed systems were designed to support vertical applications, exposing their services requires substantial reengineering. The solution described in this paper outlines a new methodology for the analysis, design and implementation of an object-oriented architecture based on the Distributed Object Computing paradigm. The resulting architecture includes two kinds of object wrappers, in order first to provide basic access to information from the legacy applications, and then to export an integrated, object-oriented view of that information. The viability of this approach is demonstrated in the implementation of ARCONET, one of the first prototypes about the Cooperative Architecture. The system, briefly described in the paper, allows Italian City Councils to access integrated information from the information system of the Italian Social Security Service, which consists of more than fifty different databases residing on several legacy mainframes.