The secret life of OCL constraints

Abstract

This paper reports on the use of OCL constraints in a German e-government project and focuses on the identification of diverse manifestations of invariants. Beyond invariants' formal content three other manifestations are identified: (a) feedback by a tool based on the processed invariants, (b) the invariant's textual explanation as a basis for a modeler who uses the invariants and (c) implicit assumptions for a model transformation resulting from the invariants.