It is well known that a simple software architecture typically evolves at least somewhat overtime. By the very nature of product line architecture, it is no surprise that its overall structure changes far more frequently: new product architectures are added, existing product architectures must be modified in response to changing functionality requirements, and defunct product architectures may have to be retired. As a result, a product line architecture finds itself in constant flux as significant parts of the product line architecture change. For instance, optional elements may turn into core elements (and vice versa), new variants may be added to a variation point, a component may be further broken down into subcomponents, wholly new product architectures may be added; or sets of existing product architectures may need to be re-factored.

Two fundamental concerns for using a product line architecture, then, are how to: (1) represent and capture the evolution of a product line architecture, and (2) support an architect in managing such evolution. The focus of ménage is then to precisely capture a product line architecture and its evolution as well as help an architect manage the evolution of a product line architecture.

The cornerstone of our approach lies in the observation that a design environment for evolving product line architectures must provide an architect with integrated architectural and configuration management functionality. Consider, for instance, an architect who wants to quickly examine a previous version of their product line architecture. The architect should not have to go to their configuration management system, check out the previous version, and then open it in their design environment. Rather, a support environment for managing evolving product line architectures must allow an architect to simply choose a version to view, with the environment itself taking care of accessing the underlying store to obtain any necessary data.