A step by step approach for adopting PLSE

Software Product Line concept [1] must be one of the solutions to increase the efficiency of the development for our various products in general. However, under a lot of pressure to shortening the development period, developers tend to avoid high initial investment of PLSE (including initial cost, training efforts and high risk) by contraries. There is an example that top-down approach is effective in overcoming this difficulty [1]. But since we can not stop our business, we consider the step-by-step approach which respected an actual result and certainty. We hope we would like to discuss with you to this approach and your experiences.