A Requirement-Based Approach to Data Modeling and Re-Engineering

This paper reports on the managerial experience, technical approach, and lessons learned from reengineering eight departmental large-scale information systems. The driving strategic objective of each project was to migrate these systems into a set of enterprise-wide systems, which incorporate current and future requirements, drastically reduce operational and maintenance cost, and facilitate common understandings among stakeholders (i.e., policy maker, high-level management, IS developer/maintainer/ end-users). A logical data model , which contains requirements, rules, physical data representation as well as logical data object, clearly documents the baseline data requirements implemented by the legacy system and is crucial to achieve this strategic goal. Re-engineering products are captured in the dictionaries of a CASE tool (i.e., in the form of a business process decomposition hierarchy, as-is data model, normalized logical data model, and linkages among data objects) and are supplemented with traceability matrices in spreadsheets. The re-engineered data products are used as follows: (1) migration of the legacy databases to relational database management systems, (2) automatically generation of databases and applications for migration from mainframes to client-server, (3) enterprise data standardization, (4) integration of disparate information systems, (5) re-documentation, (6) data quality assessment and assurance, and (7) baseline specifications for future systems. Pemdssion to copy withoutfee all or part of this material ir grantedprovided that the copies are not made or distributedfor direct commercial advantage, the VLDB copyright notice and the title of the publication and it3 date appear, and notice is given that copying b by permission of tk Very Large Dota Bare Endowment. To copy otherwise, or to republish, requires a fee on&or special permission from the EJt&wment. Proceedings of the 20th VLDB Conference Santiago, Chile, 1994 Christian T. Ramiller Hughes Information Technology Corporation