- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 08 Dec 2000 08:48:34 +0000
- To: Michael Anderson <michael@research.canon.com.au>
- Cc: "xmlschema-dev@w3.org" <xmlschema-dev@w3.org>
Michael Anderson <michael@research.canon.com.au> writes: > "Henry S. Thompson" wrote: > > > > > Let's be really careful about terminology: schema _documents_ are > > distinct from schemas. There are three things the spec. requires: > > > > 1) Any schema documents involved must be schema-valid wrt the schema > > for schemas; > > 2) They must satisfy the additional Schema Representation > > Constraints; > > 3) The schema they correspond to must satisfy the Constraints on > > Schemas. > > > > Failure to satisfy these conditions is an error, and processing with > > that schema should stop (except to provide additional feedback on > > other errors). > > > To check I've got this right. If there are any errors as defined by > (1) to (3) in any component that makes up the schema (possibly made > from multiple schema documents), then the schema has an error and > considered useless. If there was no error, then we could say the > schema is "complete" if it contains no references to unresolved > components or "partial" if it does contain such references. > > Okay? Yes. > I must admit I don't actually like the names "partial" and > "complete" because "partial" is already used ( for the same idea ) > in the [ validation attempted ] assessment outcome of an element > information item. Good point -- I used it because you suggested it! Other suggestions? > > Now on to other issues raised, ht mentioned: > > > < snip > ......in any given validation > > episode there is some schema == some set of components, probably > > derived from one or more schema documents ...... > > > > In respect to this "validation episode", I am unsure what set of components > constitute an XML Schema when validating an instance document. Any set of components which satisfy the constraints is a schema. > Q. For the purposes of validation of an instance against an XML > Schema ( being the set of components "required"), does each instance > have its own XML Schema? > A1. An instance DOES NOT HAVE an XML Schema. An instance document uses a subset > of components from one or more XML Schemas Not how I would put it. > A2. An instance HAS an XML Schema for validation, that is made up of the > components, from one or more schema documents, which are present in that > instance. s/present in/required for/ > Ie consider a very small schema document: > <schema> > <element name = "A" /> > <element name = "B" /> > </schema> > and we are validating an instance document with just one element information > item: > <A> > > In validating the instance, is the set of schema components that makes up the > XML Schema we are validating against > A1{ <element name = "A"/>, <element name = "B"/> } > OR > A2{ <element name = "A"/> } In terms of what is present in the PSVI, the spec. allows either. A2 is the minimum. > In the case of A2, it only requires the <element name = "A" /> > component and so the XML Schema that must be checked for errors is > only that component. Ah, now I see where you're going. . . > However, I think it is A1, where now the XML Schema that must be checked for > errors includes <element name="B"/> even though the instance does not use it. > Assuming this leads to another question: The schema document as a whole has constraints on it independent of it use in a particular validation episode. We could in principle have written the spec. otherwise, but we didn't. > Q. What determines the boundaries of an XML Schema? > A1.Given a schema document, all of its defined, included and referenced > components (possibly in other schema documents) Pretty much, yes, but you left out imported. I would have said 'given a set of schema documents, all the components defined, declared, imported, included or redefined...' > A2. One namespace corresponds to one XML Schema. Not at all -- this would rule out the use of 'import'. > In this case I think it is A1, which then leads to yet another question > > Q. Can the boundary of an XML Schema cross a namespace (ignoring the > case when included schema documents that have NoTargetNamespace are > converted to have the same namespace as the including schema > document)? I find the 'cross the boundary' terminology odd, but yes, see above. > A1. Yes, imported components are brought into the boundary of the XML Schema. Yes. > A2. No, imported components remain outside the boundary of the XML Schema. No. > In this case I think it is A2, which then leads to my final question > Q. Can we import a component (C) from a schema document that defines > / declares other components that do not conform to the Constraints > on Schemas, Validity Rules and Schema Information Set Contributions? > ( They will of course need to conform to the XML Schema > Representation Constraints if they appear in an XML document.) No, not at all. ht -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh W3C Fellow 1999--2001, part-time member of W3C Team 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440 Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk URL: http://www.ltg.ed.ac.uk/~ht/
Received on Friday, 8 December 2000 03:48:38 UTC