Well-formedness and typing rules for UML Composite Structures

TL;DR

This paper defines formal consistency and typing rules for UML composite structures to clarify their semantics, supporting formal validation and applicable to related modeling languages like SysML.

Contribution

It introduces a formal set of rules and an OCL formalization to disambiguate UML composite structures, enhancing their operational semantics.

Findings

Rules successfully formalized and validated on complex models

Applicable to UML, SysML, and similar hierarchical component models

Supports formal specification and validation of real-time systems

Abstract

Starting from version 2.0, UML introduced hierarchical composite structures, which are an expressive way of defining complex software architectures, but which have a very loosely defined semantics in the standard. In this paper we propose a set of consistency rules that disambiguate the meaning of UML composite structures. Our primary goal was to have an operational model of composite structures for the OMEGA UML profile, an executable profile dedicated to the formal specification and validation of real-time systems, developed in a past project to which we contributed. However, the rules and principles stated here are applicable to other hierarchical component models based on the same concepts, such as SysML. The presented ruleset is supported by an OCL formalization which is described in this report. This formalization was applied on different complex models for the evaluation and validation of the proposed principles.