W3C home > Mailing lists > Public > xmlschema-dev@w3.org > October 2001

RE: Schema being imported multiple times

From: Alexander Falk <al@altova.com>
Date: Wed, 31 Oct 2001 21:28:17 -0500
Message-ID: <9C80CCD520150E48BCFA7716ABDEFED8064BAB@teaparty.bos.altova.com>
To: "Mark Feblowitz" <mfeblowitz@frictionless.com>, "XML Spy Support Team" <support@xmlspy.com>
Cc: <ht@cogsci.ed.ac.uk>, <xmlschema-dev@w3.org>

We can definitely put that on our wishlist for a future version. But as
long as there is no standardized (i.e. W3C-endorsed) way of doing this,
we are rather reluctant to add such a thing as our own XML Spy-specific

If you take a look at the way compilers (e.g. C and C++) had to handle
the same problem, you will find that various established methods
(#ifndef __MODULENAME__ ...) exist to avoid the performance penalty of
processing such mutiply included documents more than once.

XML Spy internally does pretty much the same thing, but without forcing
the user to specify anything. Whenever we detect a Schema file that is
included or imported more than once, we try to avoid processing it

Best regards,


... Alexander Falk
... President & CEO
... Altova, Inc. - The XML Spy Company

... Member of the W3C Advisory Committee
... Member of the W3C XML Schema Working Group

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-----Original Message-----
From: Mark Feblowitz [mailto:mfeblowitz@frictionless.com] 
Sent: Wednesday, October 31, 2001 10:39
To: XML Spy Support Team
Cc: Alexander Falk
Subject: FW: Schema being imported multiple times

You heard it from the schema guy himself :)

Full reference at

You guys handle the multiple inclusion part just fine. Xerces has

Even so, it would be nice to have some support for development-time


Mark Feblowitz
XML Architect
Frictionless Commerce Incorporated
400 Technology Square, 9th floor
Cambridge, MA 02139
(617) 715-7231

-----Original Message-----
From: ht@cogsci.ed.ac.uk [mailto:ht@cogsci.ed.ac.uk]
Sent: Wednesday, October 31, 2001 10:32 AM
To: Mark Feblowitz
Cc: 'xmlschema-dev@w3.org'
Subject: Re: Schema being imported multiple times

Mark Feblowitz <mfeblowitz@frictionless.com> writes:

>    Umbrella.xsd
>       A.xsd
>          CommonTypes.xsd
>       B.xsd
>          CommonTypes.xsd

This is clearly reasonable, the REC specifically provides for it, put
pressure on your tool vendors (as you already did on me :-) to make sure
it works as spec'ed.

  Henry S. Thompson, HCRC Language Technology Group, University of
          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 Wednesday, 31 October 2001 21:28:18 UTC

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