An Agile Architecture for a Legacy Enterprise IT System

Back in the 1970s, applications mainly comprised programs written in COBOL. Many of these applications are still in operation. To meet new business demands, new applications that have to collaborate with existing programs need to be developed. It is possible to have an agile software architecture that enables easy development, extension and maintenance in COBOL. Such an architecture, and the agile development process, are presented in this article. The architectural design is a combination of the layered, component-based and service-oriented architectural patterns. It also includes features such as the centralized control of the business process, plug-and-play autonomous COBOL modules and context container for storing state data. A model-driven approach is used in the agile development process. Application models include UML class diagrams, state charts and activity diagrams from which various software artefacts and COBOL codes are generated. The architecture and development approaches were first introduced in 2004 and have been successfully applied to 13 applications since then.