Bottom-Up and Top-Down Cobol System Migration to Web Services

Moving from mainframe systems to a service-oriented architecture (SOA) using Web services is an attractive but daunting task. The bottom-up or direct-migration approach enables the effective modernization of legacy systems to Web services. Conversely, bringing migration into fruition with the top-down or indirect-migration approach is more difficult, but it achieves better migration results. Employing both approaches on the same large enterprise system is uncommon, which leaves no room for comparison. This article describes the migration processes, costs, and outcomes of applying both approaches on a real Cobol system.