[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XML spec and XSD
- Certain fairly simple data structures can only be achieved in XSD (if at all) with ridiculously verbose patterns; for instance, how do you represent a structure with five possible elements, at least one of which must be present and none of which may be repeated? The best method I have found takes about 25 lines and far too much code repetition. ... - It [rng] does not appear to relieve the complexity of representing some types of data structures (see the one described above-as far as I can tell, it would not be significantly easier to define in Relax NG than it is in XSD). If I understand correctly, in relaxNG, something like: start = x x = element x { ( a & b? & c? & d? & e?) | ( a? & b & c? & d? & e?) | ( a? & b? & c & d? & e?) | ( a? & b? & c? & d & e?) | ( a? & b? & c? & d? & e ) } a = element a {empty} b = element b {empty} c = element c {empty} d = element d {empty} e = element e {empty} does what you want, it validates <x> <a/> <b/> </x> and invalidates <x> <b/> <a/> <b/> </x> - Relax NG provides no way of specifying cardinalities other than 0, 1, and infinity! This is also a big one for me--if I need at least 2 and no more than 20 occurrences of the foo element (fairly common in my data definitions), there's NO WAY I'm going to define two required foo elements and eighteen optional ones! usually you can persuade yourself that 1,?,+,* is enough and leave cardinality checking to higher up the chain, but if you really need this, then powers of two come in handy:-) y = element y { z,z,z16,z2} z16 = z8,z8 z8 = z4,z4 z4 = z2,z2 z2 = z?,z? z = element z {empty} validates <y><z/><z/></y> but invalidates instances with less than 1 or more than 20 zs. david ________________________________________________________________________ The Numerical Algorithms Group Ltd is a company registered in England and Wales with company number 1249803. The registered office is: Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. ________________________________________________________________________
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