Architecture of product lines

A product line is a family of products designed to take advantage of their common aspects (commonalities) and predicted variabilities. A product line may be software only, e.g., a family of GUIs; software + hardware, e.g., a family of televisions; or hardware only. Where software is a part of the product line, the variability accommodated by the product line is an economic decision and strongly affects the technology and the architecture used in the design and implementation of the product line. For example, where variability is narrowly bounded, a domain specific language may be used to define the product line and generate members of it, but the market for it may be relatively narrow. On the other hand, initial investment cost may be high, production cost very low, and time to market very short. Where variability is broadly bounded, a complex software architecture may be needed, production of products may be only semi-automated, time to market may increase, but market appeal may be much wider. Empirical studies, using baseline techniques, suggest that applying product line engineering produces a factor of three to five improvement in product development cost or product development speed. This talk will focus on the architectural considerations in defining and designing a product line, particularly questions such as "What are the attributes of a good software product line architecture?" and "How might a product line architecture change the economics of software development?", introducing an open market both in architecture and in software components. I will illustrate points with examples taken from Lucent Technologies and Avaya, from the Software Product Line Hall of Fame, from building architecture, and from other industries.