[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Are we losing out because of grammars?
Marcus Carr wrote: > > Eric van der Vlist wrote: > > > Looks like we are going towards 4 different types of XML "schema" > > languages to define: > > > > - The structure > > - The datatypes > > - The rules > > - The semantic. > > This is very interesting - I wonder if we might be heading for another split > such as the one that saw XSL split into T and FO? The differences are > becoming more pronounced, and the term "schema language" is starting to lack > definition as a result. Yes, and this might be explaining why a "general" schema language is so difficult to define. > Eric (or anyone else), how do you differentiate between rules and semantics? These items would need, for sure, a detailed definition and there are overlaps. It is especially true about rules that are a technique and I should maybe not have mixed it with other items are goals. I don't think it would be very practical to design a vocabulary using only rules since there are many of them to write even for a simple structure and if you forget one of them you get a flaw in your validation check. On the other hand, rule based tools are much more flexible than datatypes or structure schema languages. Using them together would allow to keep the best of both and should be possible "both ways": 1) Use this schema and check these rules but also 2) if this rule is true then use this schema A set of useful rules would be constraints involving several nodes. A good example is the unique/key/keyref feature of (current) W3C XML Schema thats looks so much like something independant of all the other features. (They can be compared to the referential constraints added to SQL.) Semantic being rather a qualification of the "meaning" of the different nodes. Eric > -- > Regards, > > Marcus Carr email: mrc@a... > ___________________________________________________________________ > Allette Systems (Australia) www: http://www.allette.com.au > ___________________________________________________________________ > "Everything should be made as simple as possible, but not simpler." > - Einstein -- ------------------------------------------------------------------------ Eric van der Vlist Dyomedea http://dyomedea.com http://xmlfr.org http://4xt.org http://ducotede.com ------------------------------------------------------------------------
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