A guidance process to modernize legacy applications for SOA

Enterprises willing to move to SOA with Web services to challenge changes in business requirements need to modernize their legacy applications mainly by using wrapping techniques. Indeed, (1) SOA is mainly about reuse of assets; in this regard, legacy applications are running smoothly and performing critical tasks, (2) most of the business functions are locked within them, (3) legacy applications were built at high cost, and we need to preserve these investments, and (4) migration to SOA can give new life to legacy applications. A solution consists in extending the critical business logic of the legacy applications while preserving the investments, through their migration to Web services and SOA environments. This leads IT departments to select an appropriate modernization technique, which requires a guidance process to avoid any failure risk. The process would include analysis, selection of business functions, and wrapping. This work first surveys several types of approaches and automated tools that deal with one of the most modernization technique for SOA that is wrapping legacy applications into Web services. Next, it categorizes the wrapping techniques into session-based, transaction-based, and data-based wrapping techniques with regard to the three distinct parts of an application: presentation, logic, and data. This clear categorization assists in deciding an adequate technique. Then, it describes a practical guidance process for wrapping. Finally, it illustrates the guidance process with a real student information system.