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Is it possible NOT to replace entity references?

 
 
Stephan Hoffmann
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      09-05-2005
Hi,

I use XML mainly as a source for HTML. HTML browsers 'know'
certain entity references like é or ä.

When I use XSL to transform XML to HTML or XML, these entities are replaced
by what they refer to.

Is there a way to avoid that?

Two reasons to avoid that:
- On my linux machine xsltproc replaced the entities in a way that
my browser did not correctly display the resulting HTML
(I updated my linux distribution and it now works).

- &lt; is replaced by < and the output is no longer valid XML/HTML


I worked with the Python xml.sax module today,
which had the same 'issue'. I can of course perform the
inverse substitution before I write to the result document,
but that seems like a lot of unnecessary work.

Any hints?

Thanks, Stephan

 
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Martin Honnen
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      09-05-2005


Stephan Hoffmann wrote:


> I use XML mainly as a source for HTML. HTML browsers 'know'
> certain entity references like &eacute; or &auml;.
>
> When I use XSL to transform XML to HTML or XML, these entities are replaced
> by what they refer to.
>
> Is there a way to avoid that?


XSLT/XPath 1.0 at least which is the current version and the one
implemented by lots of processors and in wide-spread use does not
provide anything in its data model or in its instructions to create
entity references and to ensure that these are preserved and not
replaced by the entity content when the result of a transformation is
serialized.
You would need to look at a specific XSLT processor and check whether it
provides any mechanisms outside the standards to deal with entity and
entity references.
Saxon 6 has an extension function documented here:
<http://saxon.sourceforge.net/saxon6.5.4/extensions.html#saxon:entity-ref>

> Two reasons to avoid that:
> - On my linux machine xsltproc replaced the entities in a way that
> my browser did not correctly display the resulting HTML
> (I updated my linux distribution and it now works).
>
> - &lt; is replaced by < and the output is no longer valid XML/HTML


But &lt; and &gt; are references to entities predefined in XML and
certainly if any application supposed to output XML or HTML outputs &lt;
as a plain '<' character then the application is seriously broken.
This is a different issue, those characters '<' and '>' are obviously
special as they delimit tags in both XML and HTML and therefore need to
be escaped as &lt; respectively &gt;.
&auml; in HTML 4 stands for the character '' and that has no special
meaning in XML or HTML so if an XSLT processor or other application
supposed to output XML or HTML simply inserts '' instead of &auml; in a
document properly encoded and with the proper encoding used and declared
then there are no problems with well-formedness (or even validity).



--

Martin Honnen
http://JavaScript.FAQTs.com/
 
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Malcolm Dew-Jones
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      09-05-2005
Stephan Hoffmann ((E-Mail Removed)) wrote:
: Hi,

: I use XML mainly as a source for HTML. HTML browsers 'know'
: certain entity references like &eacute; or &auml;.

: When I use XSL to transform XML to HTML or XML, these entities are replaced
: by what they refer to.

: Is there a way to avoid that?

Perhaps judicious use of the "disable-output-escaping" attribute would
help.

That attribute can be specified in various template tags, including <text>
and <value-of> (perhaps others).

It takes the value of either "yes" or "no".

--

This programmer available for rent.
 
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Stephan Hoffmann
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Posts: n/a
 
      09-06-2005
Hi,

thanks for the detailed explanation.

You are right, these are two 'issues', I confused them because
the Python SAX parser I use replaces both the predefined and the not
predefined entity references, which is ok. I simply assumed an XSLT
processor would also replace both, but that assumption is probably wrong.

I don't know why I prefer &auml; over 'ä', maybe because 7-bit
ASCI seems to be more portable, but I can't really find a use case
where 'ä' would be less portable.

Thanks, Stephan

Martin Honnen wrote:
>
>
> Stephan Hoffmann wrote:
>
>
>> I use XML mainly as a source for HTML. HTML browsers 'know'
>> certain entity references like &eacute; or &auml;.
>>
>> When I use XSL to transform XML to HTML or XML, these entities are
>> replaced by what they refer to.
>>
>> Is there a way to avoid that?

>
> XSLT/XPath 1.0 at least which is the current version and the one
> implemented by lots of processors and in wide-spread use does not
> provide anything in its data model or in its instructions to create
> entity references and to ensure that these are preserved and not
> replaced by the entity content when the result of a transformation is
> serialized.
> You would need to look at a specific XSLT processor and check whether it
> provides any mechanisms outside the standards to deal with entity and
> entity references.
> Saxon 6 has an extension function documented here:
> <http://saxon.sourceforge.net/saxon6.5.4/extensions.html#saxon:entity-ref>
>
>> Two reasons to avoid that:
>> - On my linux machine xsltproc replaced the entities in a way that
>> my browser did not correctly display the resulting HTML
>> (I updated my linux distribution and it now works).
>>
>> - &lt; is replaced by < and the output is no longer valid XML/HTML

>
> But &lt; and &gt; are references to entities predefined in XML and
> certainly if any application supposed to output XML or HTML outputs &lt;
> as a plain '<' character then the application is seriously broken.
> This is a different issue, those characters '<' and '>' are obviously
> special as they delimit tags in both XML and HTML and therefore need to
> be escaped as &lt; respectively &gt;.
> &auml; in HTML 4 stands for the character 'ä' and that has no special
> meaning in XML or HTML so if an XSLT processor or other application
> supposed to output XML or HTML simply inserts 'ä' instead of &auml; in a
> document properly encoded and with the proper encoding used and declared
> then there are no problems with well-formedness (or even validity).
>
>
>


 
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Richard Tobin
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Posts: n/a
 
      09-06-2005
In article <kM5Te.71904$(E-Mail Removed)>,
Stephan Hoffmann <(E-Mail Removed)> wrote:

>You are right, these are two 'issues', I confused them because
>the Python SAX parser I use replaces both the predefined and the not
>predefined entity references, which is ok. I simply assumed an XSLT
>processor would also replace both, but that assumption is probably wrong.


It doesn't really make sense to contrast a parser with an XSLT
processor.

An XSLT processor will use a parser to read the document and
stylesheet, and that parser must replace entity references with the
characters they represent as it reads the files. Your problem is with
what happens on *output*: whether the program replaces characters with
entity references.

>I don't know why I prefer &auml; over 'ä', maybe because 7-bit
>ASCI seems to be more portable, but I can't really find a use case
>where 'ä' would be less portable.


XML parsers have to be able to handle UTF-8, so it won't be a problem
for any XML tools. It may be a problem for other tools (or humans)
that only understand ASCII. You can use the encoding attribute on
xslutput to tell the XSLT processor what output encoding to use
(though it isn't guaranteed to support them all). If you tell it
to use ASCII and you output a non-ascii character, it should use
a numeric characters reference. It can't use &auml; when outputting
XML because in general that won't be defined, so it will output
ä or &#xE4;.

-- Richard
 
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Peter Flynn
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      09-07-2005
Stephan Hoffmann wrote:

> Hi,
>
> I use XML mainly as a source for HTML. HTML browsers 'know'
> certain entity references like &eacute; or &auml;.
>
> When I use XSL to transform XML to HTML or XML, these entities are
> replaced by what they refer to.
>
> Is there a way to avoid that?


Not really: this is what transformation is *supposed* to do.
Martin suggested some processors might provide facilities for
doing this, but I haven't seen them in operation.

> Two reasons to avoid that:
> - On my linux machine xsltproc replaced the entities in a way that
> my browser did not correctly display the resulting HTML
> (I updated my linux distribution and it now works).
>
> - &lt; is replaced by < and the output is no longer valid XML/HTML


The topic is covered in the FAQ at http://xml.silmaril.ie/authors/cdata/

///Peter


 
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