Rearchitecting the UML infrastructure

TLDR

Metamodeling underpins computer‑automated multiparadigm modeling, yet consensus on the required metamodeling approach and the role of metamodels remains elusive. The article seeks to diagnose problems in UML metamodeling and to propose a rearchitected framework that separates logical and physical classification, unifies class and object facets, and extends instantiation across levels. The authors analyze UML’s dual classification, class/object duality, and concept replication issues, and outline solutions that rearchitect the framework by separating classification dimensions, unifying class and object facets, and enhancing instantiation mechanisms. The article concludes by highlighting practical challenges associated with implementing the proposed UML rearchitecture.

Abstract

Metamodeling is one of the core foundations of computer-automated multiparadigm modeling. However, there is currently little agreement about what form the required metamodeling approach should take and precisely what role metamodels should play. This article addresses the problem by first describing some fundamental problems in the industry's leading metamodeling technology, the UML framework, and then explaining how this framework could be rearchitected to overcome these problems. Three main issues are identified in the current framework: the dual classification problem arising from the need to capture both the logical and physical classification of model elements, the class/object duality problem arising from the need to capture both the classlike and objectlike facets of some model elements, and the replication of concepts problem arising from the need to define certain concepts multiple times. Three main proposals for rearchitecting the UML framework to overcome these problems are then presented: the separation of logical and physical classification dimensions, the unification of the class and object facets of model elements, and the enhancement of the instantiation mechanism to allow definitions to transcend multiple levels. The article concludes with a discussion of other practical issues involved in rearchitecting the UML modeling framework in the proposed way.