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    Preserve and extend legacy applications with Web Services

    by Ian Hight

    By Ian Hight

    In a previous article on legacy systems, I set out the components of a modernisation strategy. I concluded by recommending businesses take on a ‘preserve and extend’ strategy, a less costly and less risky approach than a ‘rip and replace’ strategy. The former enables the business build on the system’s existing strengths, such as reliability, security and performance, while starting to address its limitations.

    A strategic approach helps modernise core legacy systems in a win/win situation: older systems have their current usefulness preserved and they can now be extended to add more value to the business. With preserve and extend, businesses can gain a number of quick tactical wins, such as replacing any remaining green screen terminals with a graphical user interfaces (GUIs) or a web browser, which gives the application a new, fresh look and is much friendlier for end users.

    However, for a truly strategic approach to preserve and extend, I recommend the organisation seriously examines using ‘Web Services’. In this article I take a deeper dive into using this methodology.

    A comprehensive definition comes from IBM: Web Services are “self-contained, modular applications that you can describe, publish, locate, and are invoked over a network to perform encapsulated business functions. These functions range from a simple request-reply interaction to full business process interactions using Internet standards and protocols.

    Web Services help create an agile IT infrastructure and enables the business to change quicker and more cost-effectively. Much of the existing IT investment is preserved - not necessarily in all of the hardware - but in the business logic, processes and intellectual property that have made the legacy applications core to the business. 

    Towards a Web Services approach
    Using Web Services on top of current systems enables the business to provide access to existing data in a variety of different ways. The beauty of Web Services is that they enable users to modernise processes over time giving the IT department the space to move them onto open platforms. Another way to move off outdated platforms is to use automated migration, to switch from legacy applications to something like a web portal.

    By providing a library of Web Services that can be called upon to deliver features and perform tasks, a business can roll out products faster and adapt applications to meet changing customer demands. Because they are based upon open standards and are widely supported across all vendor environments, as well as across the company’s own infrastructure, Web Services do not lock the business into an architecture that could prove difficult to support in the future.

    Real world experience
    Here are examples of how I have helped two businesses benefit from deploying Web Services:

    • A pharmaceuticals importer/wholesaler used a legacy system to which was added a web-based ordering system back-ended into the inventory management system. An EDI system for placing orders electronically direct with overseas suppliers was also built. Both systems significantly improved customer service, stock despatch turnaround, and monthly processing of invoices.

    • A sports apparel retailer had a legacy system which included financials, general ledger, stock ordering and stock control - all very solid and reliable but being standalone it could not interact with the rest of the world. To preserve their existing investment an EDI system was implemented to enable the retailer to place electronic orders directly with their suppliers (in NZ and overseas), as well as enabling their NZ and international customers to order stock directly from them. A web interface was also built into the system so authenticated customers could manage relevant aspects of their orders and accounts.

    In the next article I look at the options when one company takes over another and finds itself with a set of different applications. These may not even be ‘old’ applications but are now legacy systems by definition because they now need to connect to the take-over company’s systems: welcome to ‘application integration’.

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