Featherweight OCL: A Proposal for a Machine-Checked Formal Semantics for OCL 2.5

Achim D. Brucker, Frédéric Tuong and Burkhart Wolff

16 January 2014


The Unified Modeling Language (UML) is one of the few modeling languages that is widely used in industry. While UML is mostly known as diagrammatic modeling language (e.g., visualizing class models), it is complemented by a textual language, called Object Constraint Language (OCL). The current version of OCL is based on a four-valued logic that turns UML into a formal language. Any type comprises the elements "invalid" and "null" which are propagated as strict and non-strict, respectively. Unfortunately, the former semi-formal semantics of this specification language, captured in the "Annex A" of the OCL standard, leads to different interpretations of corner cases. We formalize the core of OCL: denotational definitions, a logical calculus and operational rules that allow for the execution of OCL expressions by a mixture of term rewriting and code compilation. Our formalization reveals several inconsistencies and contradictions in the current version of the OCL standard. Overall, this document is intended to provide the basis for a machine-checked text "Annex A" of the OCL standard targeting at tool implementors.
BSD License

Change history

[2015-10-13] afp-devel@ea3b38fc54d6 and hol-testgen@12148
   Update of Featherweight OCL including a change in the abstract.
[2014-01-16] afp-devel@9091ce05cb20 and hol-testgen@10241
   New Entry Featherweight OCL