[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: fundamental facets - inquiry from the XML SchemaWorking Gr
All of these problems don't matter as much if all you are designing is a validation language. They mainly become problematic when you want to perform operations on these types either in a programming or query language. ________________________________ From: Michael Kay [mailto:michael.h.kay@n...] Sent: Fri 10/10/2003 9:13 AM To: Dare Obasanjo; 'Eric van der Vlist'; xml-dev@l... Subject: RE: fundamental facets - inquiry from the XML SchemaWorking Group I think it would be quite feasible to define a system that allowed pluggable primitive types. It should be quite possible to describe a type as an object supporting a particular IDL interface, and allow implementors to map this IDL interface to concrete programming language bindings. I'm not sure it's true that The problems that "The XQuery working group has already had a painful time dealing with the fact that ... not enough emphasis was placed on defining operations on these types just validation. The problems are different: * some of the types aren't well-enough defined (e.g. anyURI, which doesn't say what the mapping is between the lexical space and the value space) * some of them have context-sensitive lexical representations (QName, NOTATION) * the type hierarchy is badly thought out (e.g. no supertype for numerics, anyURI not being a subtype of string). * the equality operation (based on identity in the value space) is too rigid for a query language: you want to be able to treat two values as equal without losing the distinctions between them, e.g. the number of trailing zeros in a decimal * the date/time/duration types just occupy an absurdly large proportion of the space * base64 and binHex are two different lexical representations of the same values I don't think many of the problems are directly to do with operations being underspecified. It's just a badly designed and poorly specified set of not-very-primitive types. A much smaller set with better extensibility mechanisms would have served us all far better. Michael Kay > -----Original Message----- > From: Dare Obasanjo [mailto:dareo@m...] > Sent: 10 October 2003 16:21 > To: Eric van der Vlist; xml-dev@l... > Subject: RE: fundamental facets - inquiry from the > XML SchemaWorking Group > > > Really, and what spec would define how you perform operations > on these types? The XQuery working group has already had a > painful time dealing with the fact that when the W3C XML > Schema working group created their type system not enough > emphasis was placed on defining operations on these types > just validation. > > The ability to add your own primitive types seems to make > sense for validation but puts a significant burden on > technologies that depend on W3C XML Schema such as XQuery. > > ________________________________ > > From: Eric van der Vlist [mailto:vdv@d...] > Sent: Fri 10/10/2003 6:52 AM > To: xml-dev@l... > Subject: Re: fundamental facets - inquiry from the > XML SchemaWorking Group > > > > > To make it short, can't we take this opportunity to build a > datatype system in which people could add their own primitive types? > > Eric > -- > See you in Philadelphia for XML 2003. > > http://www.xmlconference.org/xmlusa/ > Upcoming schema > tutorial: > - Philadelphia (7/12/2003) > http://makeashorterlink.com/?V28612FC5 > Tutoriel XSLT: > - > Paris (25/11/2003) http://makeashorterlink.com/?L2C623FC5 > -------------------------------------------------------------- > ---------- > Eric van der Vlist http://xmlfr.org > http://dyomedea.com > (W3C) XML Schema ISBN:0-596-00252-1 > http://oreilly.com/catalog/xmlschema > -------------------------------------------------------------- > ---------- > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org > <http://www.xml.org>, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To subscribe or unsubscribe from this list use the subscription manager: <http://lists.xml.org/ob/adm.pl> ----------------------------------------------------------------- The xml-dev list is sponsored by XML.org <http://www.xml.org>, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To subscribe or unsubscribe from this list use the subscription manager: <http://lists.xml.org/ob/adm.pl>
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