RE: [xml-dev] Will "AT&T" fit in a string attribute with maxLength="4"?

["Foster, Warwick" <Warwick.Foster@ato.gov.au>]

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Is it possible for XMLSpy or the instence of the XML Schema 
to not be setup correctly?

If the validating schema does not contain a resolution for 
the entity then maybe it is defaulting back to examining the 
"&" as a string and not an entity reference. If that is 
the case then the error in XMLSpy is not in measuring the 
string incorrectly but not trapping an entity resolution error.


Warwick Foster
Australian Tax Office

-----Original Message-----
From: Thomas B. Passin [mailto:tpassin@comcast.net] 
Sent: Wednesday, 21 May 2003 05:22
To: 'Xml-Dev (E-mail)
Subject: Re: [xml-dev] Will "AT&T" fit in a string attribute with
maxLength="4"?


[Zielinski, Marek]

> I am trying to define restrictions on string lengths using Schema. The
data
> actually comes from databases, and is exchanged between two different 
> systems. I encountered a snag: when the string contains one of the
reserved
> characters, like "&", the parser automatically translates it into an
entity,
> e.g. &. This increases the length of the string, and now the 
> string
does
> not fit; the validator (I am using XMLSpy) rejects it as too long.
>

XML input can never actually contain the literal character "&" (unless it is
in CDATA, of course).  It must be written as & a m p ; (less the spaces).
Even if it were held in the database as a single ampersand character, when
serialized to xml it would have to be escaped.  Once parsed, the string
passed to the application should contain the original "&" character.

So the real question is,  does the length restriction in xml schema apply to
the raw xml or the the string stored in the infoset after parsing?

Section 2.2 of Part 1 of the Schema Rec says

"  The concepts and definitions used herein regarding XML are framed at the
abstract level of information items as defined in [XML-Infoset]. By
definition, this use of the infoset provides a priori guarantees of
well-formedness (as defined in [XML 1.0 (Second Edition)]) and namespace
conformance (as defined in [XML-Namespaces]) for all candidates for
*assessment* and for all *schema documents*. "

So clearly xml schema assessment has to take place after all the entities
and character references have been replaced by the parser.

So this looks like a bug in Spy.

Cheers,

Tom P



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