[xsl] Re: Strange Saxon error

[Stephen Arbour <sarbour@xxxxxxxxx>]

Thanks for the help, and sorry if this post should have been targeted at the
Saxon forum instead.

It does appear that the problem has to do with the strictness of the URI
comparison changing from 9.1 to 9.2. Once we fixed that the problem was
resolved. I do think the error is poorly worded, however, as it turned out the
problem was the referenced document was unable to be found by the processor,
rather than the reported error that we were violating the XSLT 2.0 rule that a
stylesheet should not operate on a result document from the same stylesheet
operation.  Configuring an XSLT pipeline seems like a better option generally
than what this particular XSLT is doing anyway.

Best,
Stephen


Date: Wed, 14 Apr 2010 18:57:19 +0100
To: <xsl-list@xxxxxxxxxxxxxxxxxxxxxx<mailto:xsl-list@xxxxxxxxxxxxxxxxxxxxxx>>
From: "Michael Kay" <mike@xxxxxxxxxxxx<mailto:mike@xxxxxxxxxxxx>>
Subject: RE: [xsl] Strange Saxon error
Message-ID: <65C186E4AD1549DAA7F06968F24C766E@Sealion>

Please report Saxon-specific problems to the saxon-help list (or forum)
available via the saxon project at sourceforge.net<http://sourceforge.net>.

Writing a document using xsl:result-document and reading the same document
using document() or doc() is not allowed by the XSLT 2.0 specification. Note
that there is no such thing as an "earlier step in the same XSL" - the order
in which instructions are evaluated is not defined, so there is no way of
knowing whether the read comes before the write, or after it: this is the
reason for this rule. It's possible that Saxon 9.2 is enforcing the rule
more rigorously than Saxon 9.1 did, for example it may be better at
recognizing the equivalence of similar URIs.

(However, if you try hard enough you can always find URIs for reading and
writing that are sufficiently different that Saxon won't recognize that they
actually refer to the same resource, and you can thereby circumvent the
rule. You just have to take the consequence that you can't be 100% sure
whether you are reading the document before or after writing it.)

It's also possible that the error is spurious: there's a recent bug with
these symptoms, see
https://sourceforge.net/tracker/?func=detail&aid=2986119&group_id=29872&atid
=397617. But from your description, it looks as if the stylesheet is doing
what the spec doesn't allow.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay

-----Original Message-----
From: Stephen Arbour [mailto:sarbour@xxxxxxxxx]
Sent: 14 April 2010 18:29
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: [xsl] Strange Saxon error

Hi all,

We have a customer that was using Saxon 9.1.0.7j using an
XSLT transform that was created by a third party. When they
upgraded to a version that uses Saxon 9.2.0.2, they started
receiving this error:

net.sf.saxon.trans.XPathException: Cannot read a document
that was written during the same transformation:
file:/C:/Program%20Files/K4%20XML%20Exporter/data/xsl/temp/21m
issouri4.xml

However, using the same XSLT in Oxygen 11 using 9.2.0.6 (HE,
PE), I can't recreate the error. It only appears when Saxon
is called by the application we support.

The XSL itself does indeed perform operations on files
created by earlier steps in the same XSL. Is this no longer a
supported workflow, but somehow Oxygen is intervening where
the standalone Saxon jars do not?

Thanks in advance for your help!

Stephen Arbour, MBA/TM
Senior Director of Product Management
MEI
610 Old York Road, Suite 250, Jenkintown, PA 19046
Phone: 215-886-5662 x291
Fax: 215-886-5681
Email: sarbour@xxxxxxxxx<mailto:sarbour@xxxxxxxxx>
<mailto:LBruce@xxxxxxxxx>AIM: sarbourmei
http://www.maned.com<http://www.maned.com/>


------------------------------

Date: Wed, 14 Apr 2010 13:58:22 -0400
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
From: Liam R E Quin <liam@xxxxxx>
Subject: Re: [xsl] Strange Saxon error
Message-ID: <1271267902.11116.200.camel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>

On Wed, 2010-04-14 at 13:29 -0400, Stephen Arbour wrote:
Hi all,

We have a customer that was using Saxon 9.1.0.7j using an XSLT
transform that was created by a third party. When they upgraded to a
version that uses Saxon 9.2.0.2, they started receiving this error:

You might find the saxon mailing list more appropriate.


net.sf.saxon.trans.XPathException: Cannot read a document that was
written during the same transformation:
file:/C:/Program%20Files/K4%20XML%20Exporter/data/xsl/temp/21missouri4.xml

Sounds right to me. You might want to consider (1) holding the
document's contents in a variable so you don't need to read it again,
(2) running XSLT twice, (3) reworking the transformation so you don't
need to re-read values you already computed... e.g. you may find that
recomputing them is perfectly fast enough.

Liam

--
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
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