Re: Running the same transformation on many input file

Indeed, I overlooked the possibility of having the controlling loop written in
XSLT 3.0 and executing the per-transformation code using fn:transform(), which
gets over the problems of changing existing XSLT code if it relies on global
variables.

Michael Kay
Saxonica

> On 15 Dec 2019, at 22:35, Dimitre Novatchev dnovatchev@xxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> > Note that there's a double overhead here: firstly you're bringing up a new
Java VM for each transformation,
> > and secondly you're recompiling the stylesheet for each transformation.
>
> Isn't the meaning of the
>     "cache" : true()
>
> key-value pair in the $options argument of `fn:transform()` exactly to
compile the stylesheet only once and to reuse the compiled result on any time
in the future the same stylesheet node or stylesheet text is passed?
>
> From the Spec (https://www.w3.org/TR/xpath-functions-31/#func-transform
<https://www.w3.org/TR/xpath-functions-31/#func-transform>):
>
> cache	1.0, 2.0, 3.0	This option has no effect on the result of the
transformation but may affect efficiency. The value true indicates an
expectation that the same stylesheet is likely to be used for more than one
transformation; the value false indicates an expectation that the stylesheet
will be used once only.
> Type: xs:boolean
> Default: true()
>
>
> Thanks,
> Dimitre
>
>
> On Sun, Dec 15, 2019 at 2:12 PM Michael Kay mike@xxxxxxxxxxxx
<mailto:mike@xxxxxxxxxxxx> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> wrote:
> Note that there's a double overhead here: firstly you're bringing up a new
Java VM for each transformation, and secondly you're recompiling the
stylesheet for each transformation.
>
> You can avoid the Java loading overhead by using ant or XProc, but I'm not
sure either of them will avoid the overhead of recompiling the stylesheet;
though if you use a a recent Saxon version, you could achieve that by
reloading the stylesheet from a pre-compiled SEF (stylesheet export file).
>
> You could write your own Java application to control the process, invoking
Saxon via the JAXP or s9api APIs - both allow you to compile a stylesheet once
and execute it repeatedly.
>
> You might be able to write the control loop in XSLT, for example by using
the collection() function, or functions in the EXPath file module. However,
this could require stylesheet changes if your XSLT code binds global variables
to values derived from the source document.
>
> In very simple cases you can take advantage of the fact that the -s option
for the Saxon command line can be a directory, in which case all the input
files are transformed to corresponding files in the -o directory.
>
> Michael Kay
> Saxonica
>
>> On 15 Dec 2019, at 09:03, Trevor Nicholls trevor@xxxxxxxxxxxxxxxxxx
<mailto:trevor@xxxxxxxxxxxxxxxxxx> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> wrote:
>>
>> Hi
>>
>> An application I am working on contains a large number of source documents
which are all run through the same series of transformations. While initially
the build process didn't take long the cost of repeatedly initialising the XSL
processor soon adds up, so I am looking at ways to streamline it.
>>
>> Our processor of choice is Saxon (currently we are using 8.7.3) so I can
shift this question to the Saxon list if there are extensions there that are
relevant.
>>
>> So the question; given a script that essentially includes the following:
>>
>> cd documents
>> for d in `cat dlist`; do
>>   cd $d
>>   for f in `cat flist`; do
>>     java -jar $SAXONDIR/saxon8.jar  -o  $f.new.xml  $f.xml
$SCRIPTDIR/transform.xsl  doc=$d  file=$f
>>   done
>> done
>>
>> is there a mechanism which would allow a single Java process to perform the
equivalent?
>>
>> Thanks
>> T
>>
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>
> --
> Cheers,
> Dimitre Novatchev
> ---------------------------------------
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