Panel discussion: Proposals for improving OCL

During the panel session at the OCL workshop, the OCL community discussed, stimulated by short presentations by OCL experts, potential future extensions and improvements of the OCL. As such, this panel discussion continued the discussion that started at the OCL meeting in Aachen in 2013 and on which we reported in the proceedings of the last year's OCL workshop. This collaborative paper, to which each OCL expert contributed one section, summarises the panel discussion as well as describes the suggestions for further improvements in more detail.Peer ReviewedPostprint (published version

Specification of Invariability in OCL

piotr AT mcs.le.ac.uk Abstract. The paradigm of contractual specification provides a transparent way of specifying systems. It clearly distinguishes between client and implementer obligations. One of the best known languages used for this purpose is OCL. Nevertheless, OCL does not provide primitives for a compact specification of what remains unchanged when a method is executed. In this paper, problems with specifying invariability are listed and some weaknesses of existing solutions are pointed out. The question of specifying invariability in OCL is studied and a simple but expressive and flexible extension is proposed. It is shown that this extension has a simple OCL based semantics.