Date Added: Jan 2010
This white paper aims to guide the reader through the problem classification and root-cause analysis surrounding legacy systems. Legacy is defined as a system in the IT estate that is difficult or costly to maintain and change. This paper presents an alternative view of why they exist, how we can simplify them and more importantly the options for preventing the recurrence of such brittle systems - a legacy inhibitor. It sheds light on the many possible drivers for change in a business, and on the nature of the change provides the roadmap on how to deal with legacy. This paper analyzes the reasons that explain why we have a rich choice of mechanisms for legacy migration and modernization, but why none truly resolve the problem that caused the legacy in the first instance. It seeks also seeks to understand the root cause of legacy in different situations, which will enable the business to remain agile, competitive and avoid second-generation legacy. It discusses the five major inhibitors to change in IT systems, and explores the underlying cause of each. It also considers how technology can be used to overcome these barriers. Finally, this paper concludes that the root cause of legacy is our reliance on the human in the software development process, and that the process of automation should alleviate the underlying problems of legacy systems.