A database for configuration management

The checkin/checkout model of typical design databases only distinguishes a global repository with full consistency and global visibility from local workspaces with only local visibility and without consistency constraints. Communicating versions between developers means passing them through the global repository and checking consistency. Passing incomplete objects or prototypes is not supported by such databases. The authors suggest that visibility be linked to consistency and that there be arbitrary levels of visibility/consistency in a design database. They present an engineering repository, defined by a database scheme and a set of transactions allowing for maximum concurrency of development. According to different consistency assertions the design objects are arranged in a tree-like structure with the root corresponding to the globally visible, consistent repository and the nodes corresponding to local workspaces