Evolution and Configuration Management

As with conventional software engineering, the software artifacts in a software product line (the assets, decisions, and products) are subject to maintenance and evolution. That variation over time, due to evolution, is distinct from the variation found in the variation points in the software assets, due to the variation among products in the product line space. This distinction is characterized as variation in time versus variation in space.

Conventional configuration management can manage some of the issues of variation in time for a software product line. However, the problem is complicated by dependencies among the different software artifacts in the production process. As illustrated below, evolutionary changes to an artifact may require that those changes be propagated to interdependent downstream or upstream artifacts in the production workflow.

• Update paths. A change made to an upstream artifact may need to be reflected in all existing downstream artifacts previously produced from the original artifact.
• Feedback paths. If downstream artifacts are mutable, then a change made to a downstream artifact may need to be fed back to the original artifact or artifacts from which the original downstream artifact was produced. Automated production and replay can eliminate the need for manual updates and all feedback paths.

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