Reengineering typically involves moving to a totally new architecture and technology while retaining the business functionality of the existing legacy system intact in the new system. The key difficulty in such projects is the fact that the business rules are frequently embedded in monolithic legacy systems written decades ago. When one considers that over 80 percent of the core business rules may not really change, going by the traditional development route, makes the entire project too expensive and also prone to major risks.

NIIT has developed a comprehensive reengineering methodology that is flexible for individual situations. Legacy system comprehension is frequently one of the key success drivers. NIIT uses a comprehensive business rule extraction methodology called BTAM.

BTAM stands for the Business Processes - Tasks - Activities - Methods based model. The business rules extracted by NIIT from the legacy system are used as a base by the client's team to derive the business rules and requirements for the new system. The entire traceability matrix, from business requirement -> tasks -> activities -> methods -> Programme code, is established, ensuring that requirements do not get missed in the new system.

On release of the finalised requirements for the new system, a Re-engineering of the complete end-to-end solution is undertaken.. This solution offers re-engineering of presentation, business logic and data from the legacy environment to an open, business-driven, flexible target environment. UI and workflow typically changes completely in the new system. This approach brings in the advantages of legacy comprehension in terms of retaining and reusability of legacy system business rules along with the flexibility to move forward with the latest state-of-the-art technology/platform options based on the principles of the SOA architecture. NIIT Technologies has solutions that integrate the new reengineered application with other retained legacy or non legacy applications, using middle ware and connectors.

NIIT has also successfully used its reengineering approach in iterative development environments such as the Rational Unified Process.