Detecting OCL Traps in the UML 2.0 Superstructure: An Experience Report

Currently, the OMG is developing a new version of the Unified Modeling Language (UML), UML 2.0, which involves major innovations in its metamodel. As for previous versions of the UML, the Object Constraint Language (OCL) is employed to give restrictions on the use of UML and for the formulation of additional operations. It seems that the OCL expressions in the current version of the UML 2.0 Superstructure have not been checked with a tool. In this paper we report on an experiment in checking and validating the well-formedness rules and operation definitions of the UML 2.0 Superstructure w.r.t. syntax and type checking by using our tool USE (UML-based Specification Environment). For this purpose we classify the errors detected by USE in appropriate error categories. We develop statistical information on error frequencies w.r.t. package location and error category. All errors detected by USE and their detailed description are made available in a separate EXCEL file.