Experience with the architectural design of a modest product family

Many product families are modest in the sense that they consist of a sequence of incremental products with, at any point in time, only a few distinct products available and minimal variations among the products. Such product families, nevertheless, are often large, complex systems, widely deployed, and possessing stringent safety and performance requirements. This paper describes a case study that tends to confirm the value of using a product-line approach for the architectural design of a modest product family. The paper describes the process, design alternatives, and lessons learned, both positive and negative, from the architectural design of one such family of medical image analysis products. Realized benefits included identifying previously unrecognized common behavior and sets of features that were likely to change together, aligning the architecture with specific market needs and with the organization, and reducing unplanned dependencies. Most interesting were the unanticipated benefits, including decoupling the product-family architecture from the order of implementation of features, and using the product-family architecture as a 'guiding star' with subsequent releases moving toward, rather than away from, the planned architecture.