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Re: [xsl] XSLT 3.0 processor accepting non well-formed XML inputs

2019-03-01 05:43:56
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 lives.

It's the responsibility of the application designer to decide the right 
trade-offs between performance, security, reliability, and other system 
qualities.

Michael Kay
Saxonica

On 1 Mar 2019, at 11:23, Mukul Gandhi gandhi(_dot_)mukul(_at_)gmail(_dot_)com 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> 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 following,

<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(_at_)acm(_dot_)org

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