Technical Report: Incremental Configuration Management Based on Feature Unification

We apply feature logic to the problem of incremental configuration management. Feature logic has originally been developed in computer linguistics as a knowledge representation and inference mechanism. It offers a uniform formalism for the description of variants and revisions, where sets of versions rather than single versions are the basic units of reasoning. Feature logic thus opens a whole algebra of version sets, which includes specific configurations as special cases. Our approach allows for interactive configuration management, where a configuration thread is constructed by adding or modifying configuration constraints until either a complete configuration or an inconsistency can be deduced. A set of versions of a software component can be represented and processed as a single source file enriched with preprocessor statements. Thus, our tool can be used as an intelligent front end to more traditional techniques.