RE: Sets and bags || UML and PUML going astray



Date view Thread view Subject view Author view

Perdita Stevens (Perdita.Stevens@dcs.ed.ac.uk)
Wed, 24 Jan 2001 19:28:50 +0000 (GMT)


Daniel Jackson writes: D> forgive my directness I'm going to match or exceed it. Please bear in mind that I'm currently at a workshop which is trying to agree an interchange language for use by all reengineering tools doing all reengineering tasks at all stages of the lifecycle and with all (combinations of) languages. This makes agreeing UML look like a picnic. Yes, graphs it is, but we've spent the whole week being brutally exposed to how little of the problem saying that solves... (Don't let's get into reengineering languages here, though.) D> both of these seem wrong to me, because they're both hopelessly bound up D> with the semantics of a particular programming language. D> if you don't D> have classes, attributes, messages, etc, none of this makes sense; Actually, if we had a modelling language that worked and was well defined for any language that had classes, objects, attributes and messages, I should say we were a long way forward. Frankly, I am yet to be convinced that UML will ever be the best modelling language outside that domain and that doesn't bother me much. D> if you want to make it precise, you'll need to elaborate what you mean D> by these terms, and thus bind the modelling language to a particular D> programming language. I don't get the "thus". I think an abstraction that covered several languages is perfectly possible. Say Java, C++ and Smalltalk, for concreteness. Yes, there will be subtleties to deal with, but I think they'll be manageable. D> this characterization of the static view is completely syntactic; Yes, indeed. D> to me, this suggests it won't be of much use (since it's relationship to D> the program text is trivial). Sorry? It has to be difficult to be useful? D> the dynamic view doesn't appeal to me either; D> i can't see what use cardinalities will be in such a context. Indeed, that's a problem, as I pointed out. D> a better approach, i think, is to give a semantics to the notation that D> maps it to a domain of mathematical objects that is precise and simple. err, no argument there, if we can produce such a semantics that is useful, i.e. that doesn't prevent people doing useful things with the notation. D> then, in a second step, we interpret the artifacts of interest by D> mapping to this domain. Hmm. I can suggest a great simple precise mathematical domain such that we can map the notation and the artefacts to it. The one point set. There are some missing conditions on what it would take to be useful here! I'm not denying you can do some useful things with your simple relational model; I know that you have. But I think you're being naive about UML: and I am really sick, this week especially, of the fallacy that if you can map into something you have ipso facto achieved something useful. I'm sure that's not what you meant, but that's how it sounded. Perdita -- Dr. Perdita Stevens Division of Informatics, University of Edinburgh www.dcs.ed.ac.uk/home/pxs Fax: +44 131 667 7209


Date view Thread view Subject view Author view