Using Patterns to Model Variability in Product Families

Feature Product family engineering permits soft ware component reuse, which saves both time and money. To succeed, the process must suppor t variabilit y among the family's systems. The authors developed a simple method that uses patterns to model variabilit y and applied it to development of spacecraft mission-planning systems. or each of its spacecraft, the European Space Operations Centre (ESOC) develops a new mission-planning software system. MPSs are increasing in complexity, even as tighter budgets require greater efficiency in mission development and operations. This led ESOC to consider developing spacecraft MPSs that can be customized across a range of missions. ESOC's approach to this is to develop a product family of spacecraft MPSs. A product family is a group of similar products within a market segment, such as mobile phones, pensions, or spacecraft MPSs. Product-family engineering can generate significant savings in cost and time by permitting software-component reuse. But to succeed, product family engineering must provide mechanisms to support variability among the family's systems. This variability permits a product family to evolve and maintain its relevancy. We have developed a simple method that uses patterns to model variability. We start by analyzing existing user requirements from systems within the family and identifying discriminants. We then build an object-oriented family model, using a set of predefined patterns to model the discriminants. This model lets developers identify and select desired features and build new family systems.