The SOA frontier: Experiences with three migration approaches

Service Oriented Architecture (SOA) and Web Services are the current trend to integrate large and distributed systems, which is a common situation in both the business and government worlds. However, within these worlds, systems are commonly written in COBOL because they were developed several decades ago. Therefore, migration of COBOL systems into service-oriented architectures becomes a necessity. Two main approaches are used to migrate COBOL systems to SOA systems: Direct and indirect migration. Direct migration implies wrapping the current COBOL routines of a system with a software layer developed under a newer platform that can be used to offer Web Services. In contrast, indirect migration requires re-designing and re-implementing the COBOL routines' functionality using a newer platform as well. In this chapter, the authors propose a novel migration approach, which takes the best of the two previous approaches. To assess the advantages and disadvantages of these approaches, this chapter presents a case study from a government agency COBOL system that has been migrated to a Web services-based system using the three approaches. As a result of having these migration attempts, the authors present the trade-off between direct and indirect migration, the resulting service interfaces quality, and the migration costs. These results also show that this new migration approach offers a good balance to the above trade-off, which makes the approach applicable to similar COBOL migration scenarios.