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Re: XSLT 3.0 processor accepting non well-formed XML

Subject: Re: XSLT 3.0 processor accepting non well-formed XML inputs
From: "Wendell Piez wapiez@xxxxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 1 Mar 2019 22:10:56 -0000
Re:  XSLT 3.0 processor accepting non well-formed XML
Hi Mukul,

Like Michael, I hesitate lest I confuse the particular rules of a
particular human-made thing with 'ethics' more generally. I suppose
there might be said to be an ethics of systems building or ethics of
programming, but I hardly think permitting syntax problems (of
whatever nature) to go undetected presents - in itself - ethical
problems. Quite the contrary: I can imagine times it might be
'unethical' to go chasing after wf errors when it is known ahead of
time, they make no practical difference ...

In other words, it's all (very) relative and situational, isn't it.

It's true that a 'conformant XML processor' is obliged to stop parsing
when it finds well-formedness errors, but this does not mean it is
obliged to continue parsing to the (nominal) end of the (nominal)
document, does it?

Without this particular example to hand, I actually wrote about this a
few years ago -- perhaps Mike remembers this paper (I remember at
least he was kind to me about it) --


The ethics are not in whether you follow all the rules all the time,
but in how you follow them and to what end(s).

Cheers, Wendell

On Fri, Mar 1, 2019 at 6:44 AM Michael Kay mike@xxxxxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> Ethics to me is about building systems that don't harm people. It's not
about conforming to rules and regulations.
> In practice it is often useful to be able to extract information from the
start of an XML document (e.g. an attribute of the root element) without
reading gigabytes of data that follow. Most XML parsers therefore provide an
option for the application to terminate parsing as soon as they have obtained
the information they need. We can debate whether a conformant XML parser is
permitted to provide such an option; in practice it really doesn't matter:
parsers will provide such an option because it is needed.
> This rule in the XSLT spec for streaming is just warning you that if your
stylesheet does something like
> <xsl:source-document href="big.xml">
>   <xsl:sequence select="string(/*/@version)"/>
> </xsl:source-document>
> then it may succeed even though big.xml contains errors after the first
start tag. Is it "ethical" to provide such an option? Absolutely. In some
cases, extracting the data in microseconds rather than seconds might save
> It's the responsibility of the application designer to decide the right
trade-offs between performance, security, reliability, and other system
> Michael Kay
> Saxonica
> > On 1 Mar 2019, at 11:23, Mukul Gandhi gandhi.mukul@xxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hi all,
> >    I've got some chance to try XSLT 3.0's streaming features, and have
found them useful. I've a slight question as below,
> >
> > The XSLT 3.0 spec, in the section "2.12 Streamed Validation" says
> >
> > <quote>
> > A streamed transformation that only accesses part of the input document
(for example, a header at the start of a document) is not required to continue
reading once the data it needs has been read. This means that XML
well-formedness or validity errors occurring in the unread part of the input
stream may go undetected.
> > </quote>
> >
> > As per above quoted text, is it ethical for an XSLT (3.0) processor to
provide a functionality that's based on a non well-formed input XML document?
> >
> >
> >
> >
> > --
> > Regards,
> > Mukul Gandhi
> >
> > alt email : mukulgandhi@xxxxxxx
> >
> > XSL-List info and archive
> > EasyUnsubscribe (by email)

Wendell Piez | wendellpiez.com | wendell -at- nist -dot- gov
pellucidliterature.org | github.com/wendellpiez |
gitlab.coko.foundation/wendell  - pausepress.org

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