Richard J. Welke, Ph.D.
(c) Meta Systems, Ltd.
October 7, 1988
Download article (255 KB PDF) - available again after many years!
Many of the fundamental differences between today's Language Workbenches can be attributed to their different meta-metamodels: the set of concepts they offer language designers. This article explains the benefits, problems and differences between the main meta-metamodels, which are still in use today: Eclipse's Ecore (≈EAR), Microsoft's DSL Tools (≈OPRR without n-ary relationships), and MetaEdit+'s GOPPRR (≈WOPRR extended with ports).
The keynote "The Model Repository: More than just XML under version control" by Steven Kelly at the 2008 OOPSLA Workshop on DSM paid homage to this article. Dr. Welke has given his kind permission for the original article to be made available here. The version available here was scanned and OCR'd from a photocopy of the full white paper from Meta Systems. Several versions of the article were published; the first below was the most comprehensive and closest to the original white paper, the last is the most widely quoted.
Welke, R.J.: "The CASE Repository: More than another database application," Proceedings of 1988 INTEC Symposium Systems Analysis and Design: A Research Strategy, Atlanta, Georgia, Cotterman, W.W. and J.A. Senn (eds.), Georgia State University, 1988.
Welke, R.J.: "Meta Systems on Meta Models," C/A/S/E Outlook, 1989, Vol.4 (December 1989), pp. 35-44.
Welke, R.J.: "CASE Repositories: More than another DBMS Application," Challenges and Strategies for Research in Systems Development, Cotterman, W. and J. Senn (eds.), J. Wiley, Chichester, UK, 1992, pp. 181-214.
Readers today may be confused by some of the terminology: Welke was often inventing both the concepts and the terminology, and whilst concepts are valid in any time, the terminology we use today has taken a different route. Welke's terminology is described on page 3; what he calls a meta-model is nowadays more commonly referred to as a meta-metamodel; what he calls a meta-schema is nowadays referred to as a metamodel.
There is increased awareness within the CASE (Computer-Aided Software Engineering) arena, of the need for a central Repository of system description information. This is brought on by a growing recognition that only with a strong central repository, can CASE tool sets be integrated, cope with large projects, provide full life-cycle support, produce complete documentation, perform system-wide validation and verification, and adequately control a project. In examining the various approaches chosen or proposed by various vendors it is apparent that, for many users and providers, a CASE Repository is nothing more than an off-the-shelf database management system into which specification information is directly placed. However, as this paper will demonstrate, commercially available database systems cannot be directly employed as a CASE repository.
Dr. Welke is Director of the Center for Process Innovation, professor and previous chairman of the CIS department at Georgia State University. Prior professorships include appointments in the Netherlands (TU-Delft as Cor Wit Research Professor, Erasmus/RSM as HL, Business Informatics) and Canada (McMaster University).
Dr. Welke was co-founder of the information systems discipline's now-major academic organizations, (ICIS, AIS, TIMS College on IS, and IFIP WG 8.2). He has been the ICIS program chair (1986) and co-conference chair (1996) as well as serving on its executive committee.
He has started, owned and managed two Computer-aided Software Engineering (CASE) companies; one in Canada (Methodsworks) and the other in the US (Meta Systems).