[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

RE: validation against xml schema (xsd)

  • From: "Johnson, Matthew C. (LNG-HBE)" <Matthew.C.Johnson@l...>
  • To: "George Cristian Bina" <george@o...>
  • Date: Fri, 6 Mar 2009 08:04:35 -0500

RE:  validation against xml schema (xsd)
George,

Thanks very much for this information and for your thoughts.  They will
be useful!

Matt

> -----Original Message-----
> From: George Cristian Bina [mailto:george@o...]
> Sent: Thursday, March 05, 2009 4:00 PM
> To: Johnson, Matthew C. (LNG-HBE)
> Cc: xml-dev@l...
> Subject: Re:  validation against xml schema (xsd)
> 
> Hi Matt,
> 
> You can do a first parse and stop once you reach the root element, for
> instance by throwing an exception on the first startElement callback.
> That will give you enough information about the document to determine
> the schema to use. While you do this parse you can buffer what the
> parser reads and then start the validation feeding the parser with the
> buffered content and then the remaining content of your document. You
> can find an example of this in Jing, see the AutoSchemaReader and the
> RewindableReader and RewindableInputStream classes:
> 
> http://code.google.com/p/jing-
>
trang/source/browse/trunk/mod/validate/src/main/com/thaiopensource/valid
at
> e/auto/AutoSchemaReader.java
> http://code.google.com/p/jing-
>
trang/source/browse/trunk/mod/validate/src/main/com/thaiopensource/valid
at
> e/auto/RewindableReader.java
> http://code.google.com/p/jing-
>
trang/source/browse/trunk/mod/validate/src/main/com/thaiopensource/valid
at
> e/auto/RewindableInputStream.java
> 
> Best Regards,
> George
> --
> George Cristian Bina
> <oXygen/> XML Editor, Schema Editor and XSLT Editor/Debugger
> http://www.oxygenxml.com
> 
> 
> Johnson, Matthew C. (LNG-HBE) wrote:
> > Hello,
> >
> >
> >
> > I am wrestling with a choice and would like to ask for opinions.  In
> > validating XML instance documents against a W3C XML Schema instance,
I
> > can either rely use @xsi:schemaLocation and rely on it as a hint or
I
> > can infer which schema to apply using some other piece of
information
> > from the document.  I believe one of the arguments against using
> > @xsi:schemaLocation is that the consuming application should
arguably be
> > in a better position to determine which schema to apply than the
> > producer.  This is especially true in situations where a document
could
> > be valid against multiple schemas.  My scenario is that a document
is
> > either valid or not but I do not want to discount this argument.
> > Another argument against is that it is defined as only a hint and
that
> > not all tools support it, although in my case, the tools do support
it.
> >
> >
> >
> > My question is, if I did not use/provide @xsi:schemaLocation, what
are
> > some suggested options and means to determine the schema?  I will
almost
> > certainly be using a catalog (OASIS) so I believe this will play a
role
> > in the decision.  One option I have considered is using the
namespace
> > URI of the root element as a sort of public identifier that could be
> > used by the catalog resolver but this has limited support in
> > "off-the-shelf" parsing solutions.  For example, Xerces (Java)
supports
> > this through their (XNI) XMLCatalogResolver class but standard SAX
> > EntityResolver(2) does not expose/report namespaces.
> >
> >
> >
> > The piece that is bugging me a little is that, regardless of the
means
> > of determining the schema, it feels like an extra
> > step/pass/look-into-the-document is required before the actual parse
of
> > the document.  Relying on @xsi:schemaLocation feels much more like
> > relying on a DOCTYPE for a DTD in that it is recognized during the
main
> > parsing step represented by a standard API call (e.g.
> > xmlreader.parse(...)) (even if that call does a few passes itself).
> >
> >
> >
> > I could even remove the notion of XSD here and ask the same question
if
> > I were validating against one of multiple RelaxNG schemas.  Since
RNG
> > does not have the standardized equivalent of @xsi:schemaLocation
that
> > allows the instance document to say "validate me to this schema", it
> > feels like a pre-pass would be needed here too.  The Oxygen editor
uses
> > a processing instruction to indicate which RNG file it should use
for
> > validation but I am unsure whether the implementation first does a
pass
> > to get the PI and then another to validate or whether it is able to
> > validate in a single pass.
> >
> >
> >
> > Am I missing anything here?  I appreciate any comments,
alternatives,
> > etc.  Thanks, I appreciate it!
> >
> >
> >
> > Matt
> >
> >
> >
> > PS:  My scenario involves collections of heterogeneous content types
so
> > each document could be of one of several schema types (but only
valid to
> > one).  The effect is that I could not rely on doing a pre-parse (or
> > regex) on the first of a collection and assume that all docs in that
> > collection are the same.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >


[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index]


PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
 

Stylus Studio has published XML-DEV in RSS and ATOM formats, enabling users to easily subcribe to the list from their preferred news reader application.


Stylus Studio Sponsored Links are added links designed to provide related and additional information to the visitors of this website. they were not included by the author in the initial post. To view the content without the Sponsor Links please click here.

Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.