Forming a Legacy System Modernization Method Base

Legacy system modernization is a topic in which a considerable amount of research has been done, and is practiced in industry to a great extent. Yet, many legacy systems are still in operation today, causing problems such as high maintenance costs and a lack of knowledge. Modernizing legacy systems can result in great cost savings and systems withstanding more loads. These benefits will ultimately be felt by the consuming society, making legacy modernization a socially relevant topic. By offering legacy modernization practitioners a means to more effectively modernize legacy systems, this research aims to solve such problems. Multiple legacy modernization methods from academia are investigated, and a rigorous industrial case study is performed looking at four legacy modernization projects. Documentation is analysed and practitioners from industry are interviewed in order to get a good overview of four successful legacy modernization projects. The methods are split up in separate parts called method fragments which are classified according to a legacy system modernization process model. This process model has been developed in academia and contains six phases that are part of the modernization process. This provides practitioners a good means to select a method fragment fitting their situational needs. By investigating academic legacy modernization methods and performing case studies on industrial legacy modernization methods, this thesis investigates the gap between academia and industry. A comparison of the methods identified in this research provides insights on differences and identifies areas of interest for future research. A method comparison matrix is used to compare the activities of the methods and a reflection on the use of this matrix is provided. Finally, a process model for method-extraction case studies is proposed. This process model guides researchers when investigating software projects, that have as a goal to model a method. The focus lies on a good use of documentation and interviewing to result in a correct method description from which a model can be made