Improve Business Agility of Legacy IT System

Introduction

Enterprise IT systems usually undergo a long period of evolution. This decade long, the software projects evolved into some of the most complex software systems. For large corporations, mainframe applications programmed in COBOL often form the backbone of the IT structure. The operation and maintenance costs for these applications are usually very high. Worst of all is the lack of business agility. Contemporary businesses have placed heavy requirements on enterprise IT infrastructure to operate in highly stable yet flexible and fast environments, and to introduce new features and operation processes in order to meet their constant growth. New features usually take far too long and cost too much to build.

Maintaining and upgrading legacy systems is one of the most difficult challenges many companies face today. They struggle with the problem of modernizing these systems while keeping the day to day operation intact. Despite their obsolescence, legacy systems continue to provide a competitive advantage through supporting unique business processes and containing invaluable knowledge and historical data.

With the advances in Web technology, corporations must consider integrating Web-based applications with their existing applications. The integration can be done using SOA (service oriented architecture) in the mainframe. The mainframe applications become service providers and Web-based applications running on an application server are service consumers.

To achieve business agility, SOA alone is not sufficient. Managing the complexity of the applications behind the services can still be a challenge. This chapter presents an approach to meet this challenge. The solution framework of this approach has the following features:

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  Modular and pluggable for architecture business and system component integration

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  Reuse in terms of design and code patterns

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  Use model driven approach and code generation in the development process

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  Test infrastructure for unit testing, component integration testing and service testing

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  Adapt an agile development process.

The software development approach is called the “Gaby Paradigm”. Gaby is not the inventor of this paradigm. Rather the methodology and approach are for developers like Gaby, who has little programming experience. Using the techniques described in this chapter, developers like Gaby could focus on business modeling instead of programming. Gaby had been able to develop up to 80% of the programs for a project that normally would need a team of five to six developers. The reason for this achievement will be explained later in this chapter.

The development approach presented in this chapter is based on practical experience from a re-engineering project of a legacy IT system in a large corporation. The project started in 2000. The development approach has been evolving for over 10 years. During this period, a lot of works covering advances in SOA and model driven software development technologies have been published. Many important aspects like strategic planning for SOA (Sweeny, 2010), SOA life cycles (Bell, 2008), architectural design and patterns (Erl, 2009), service governess (Balzer, 2004) etc. are well covered. Fundamental and advanced SOA design principles can be found in a tutorial by Erl (Erl, 2008). SOA modeling and analysis using and modeling patterns have been presented by Bell (Bell, 2008; Bell, 2010). In his books, Bell used a set of modeling notations particularly for SOA modeling. Leveraging legacy software objects with SOA has been addressed by a number of authors (Roshen, 2009; Umar & Zordan, 2009; Sweeny, 2010). Most approaches suggest using an enterprise service bus (ESB) in a SOA platform to integrate heterogeneous software systems. Existing legacy software objects are wrapped with wrappers or adaptors to form services that can be consumed through the ESB. New applications or enhancements are implemented in the SOA platform and activate the legacy software objects via the service layer as service consumers. The focus of this chapter, on the other hand, is on an approach to establish SOA and develop services on an existing legacy mainframe platform with COBOL.