Re: [xml-dev] Requirements on validation: (1) combine schemas, (2) divid

["bryan rasmussen" <rasmussen.bryan@gmail.com>]

Hi Roger,

I think I have to agree on this, it is sort of a mis-characterization,
or at least the argument should be that while XML Schema has features
that allow for doing what you want that they are inadequately
implemented or that the way that one must work with them are not
useful in practice, but at any rate it is much more ambiguous than
just saying flat out that XML Schema can't do it.

one examples of how XML Schema might enable these kinds of
requirements is that since XML Schema does not mandate a Root element
you can divide a document into pieces and validate every element. Some
processors specify that the root element of your document must be in
the target namespace of the schema but there are a number of
processors that don't.  IIRC XSV doesn't require a document element in
the target namespace of the schema. Thus if your schema imports other
schemas with other target namespaces validation will start when an
element in one of those target namespaces is reached even if the top
level element of your document is in a namespace that you are not
validating. Personally I have never considered this to be a feature
and there are a lot of people who complain about it, but looking at it
from the way you describe it certainly could be seen as a check mark
on your requirements.

Cheers,
Bryan Rasmussen


On Wed, Apr 30, 2008 at 2:04 AM,  <noah_mendelsohn@us.ibm.com> wrote:
> Roger Costello wrote:
>
>  > - It should be possible to divide non-monolithic documents into pieces
>  > and then validate each piece against one of the schemas.
>  > (divide-and-validate)
>  >
>  > Do existing schema languages meet these requirements?
>  >
>  > - No, you have to understand all  schemas very well and change them.
>  > - No, you have to validate the entire document against the combination
>  > of all schemas.
>  >
>  >    - W3C XML Schema
>  >    - RELAX NG
>
>
>  I don't think you've accurately characterised the XSD language.  You can,
>  to a significant degree, to incremenal validation if your validator
>  supports it.  First of all, you can get a degree of modularity by using
>  facilities like xs:include.  So, if you have an "outer" schema that
>  includes a bunch of "inner" pieces, you can also often do validations
>  using just the inner bits by identifying one or more of the inner schema
>  documents to your schema processor when that's what you want. Furthermore,
>  the Recommendation makes clear that [1]:
>
>  "With a schema which satisfies the conditions expressed in Errors in
>  Schema Construction and Structure (§5.1) above, the schema-validity of an
>  element information item can be assessed. "
>
>  Note that the above does not refer to an entire XML document, but to a
>  given element.  Of course, most validators take the option of validating
>  whole documents and starting with the root, but that's not required.  You
>  can in principle start with any element in the tree.  XSD does this in
>  part so you can divide things, as Murata-san suggests, and in part so that
>  tools like editors can do incremental revalidation as small parts of a
>  document change.  The same section [1] points out that you can, in
>  principle, identify any global element declaration or complex type to use
>  in validating the element information item you've chosen.
>
>  I'm not saying that all of this provides everything that you or Murata-san
>  might want, but it's a little strong to say that XSD does not meet the
>  requirement at all.
>
>  Noah
>
>  [1] http://www.w3.org/TR/2004/PER-xmlschema-1-20040318/#validation_outcome
>  --------------------------------------
>  Noah Mendelsohn
>  IBM Corporation
>  One Rogers Street
>  Cambridge, MA 02142
>  1-617-693-4036
>  --------------------------------------
>
>
>
>
>
>
>
>
>  "Costello, Roger L." <costello@mitre.org>
>  04/27/2008 04:33 PM
>
>         To:     <xml-dev@lists.xml.org>
>         cc:     (bcc: Noah Mendelsohn/Cambridge/IBM)
>         Subject:        [xml-dev] Requirements on validation: (1) combine
>  schemas, (2) divide a document into pieces and validate each piece, (3)
>  use different schema languages, (4) validators work together
>
>
>
>
>  Hi Folks,
>
>  Here are a few snippets from slides by MURATA Makoto:
>
>  Requirements on validation#1
>
>  - It should be possible to combine schemas representing vocabularies
>  easily.
>
>  - It should be possible to divide non-monolithic documents into pieces
>  and then validate each piece against one of the schemas.
>  (divide-and-validate)
>
>  Do existing schema languages meet these requirements?
>
>  - No, you have to understand all  schemas very well and change them.
>
>  - No, you have to validate the entire document against the combination
>  of all schemas.
>
>    - W3C XML Schema
>    - RELAX NG
>
>  Requirements on validation#2
>
>  - It should be possible to use different schema languages for different
>  vocabularies.
>
>  - Validators for many schema languages should work together.
>
>  Do existing schema languages meet these requirements?
>
>  - No, you are forced to use one schema language.
>
>  - No, you have to use one validator.
>
>    - W3C XML Schema
>    - RELAX NG
>
>  More... www.asahi-net.or.jp/~eb2m-mrt/svgopen/200409SVGOpen.ppt
>
>  /Roger
>
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