[XSL-LIST Mailing List Archive Home] [By Thread] [By Date]

Re: [xsl] [ANN] Saxon/C - Saxon for the C/C++ and PHP platforms


Subject: Re: [xsl] [ANN] Saxon/C - Saxon for the C/C++ and PHP platforms
From: Michael Kay <mike@xxxxxxxxxxxx>
Date: Fri, 29 Nov 2013 11:52:29 +0000

Thanks for this useful data.

I'm a little sceptical about the virtues of being 90%, or even 99%, compatible
with another API. If you can't achieve 100%, you're going to create the
illusion that people don't need to worry about the differences and you're
going to get bug reports when people hit the 10% or 1% of cases where the
behaviour is different. We see this effect with JAXP: because the syntax of
the interface is the same, people complain when the behaviour is different,
even though the spec allows such differences.

So perhaps some kind of adapter or bridge module that translates common cases
might be a better approach than attempting to emulate libxslt2 interfaces
natively.

Michael Kay
Saxonica


On 29 Nov 2013, at 09:59, Tony Graham <tgraham@xxxxxxxxxx> wrote:

> On Thu, November 28, 2013 8:32 pm, Michael Kay wrote:
> ...
>>> So we need to create a libxslt2 bridge now right?
>>
>> You mean in terms of bridging the API? We haven't really explored what's
>> feasible yet in terms of libxslt2 and libxml cooexistence. At the moment
>> if you've got data in a libxml tree you have to serialize and reparse to
>> get it into Saxon. I don't know if we'll ever be able to do better than
>> that; I suspect the overheads of doing it this way are lower than the
>> overheads of accessing the libXML tree node-by-node from the Java
>> environment, but we'll find out in due course.
>
> The top-level API for libxslt is at
> http://www.xmlsoft.org/XSLT/html/libxslt-transform.html
>
> The top level of the top-level API would be xsltApplyStylesheet [1]:
>
> xmlDocPtr	xsltApplyStylesheet	(xsltStylesheetPtr style,
> 					 xmlDocPtr doc,
> 					 const char ** params)
>
> xsltApplyStylesheetUser [2]:
>
> xmlDocPtr	xsltApplyStylesheetUser	(xsltStylesheetPtr style,
> 					 xmlDocPtr doc,
> 					 const char ** params,
> 					 const char * output,
> 					 FILE * profile,
>
> xsltRunStylesheet [3]:
>
> int	xsltRunStylesheet		(xsltStylesheetPtr style,
> 					 xmlDocPtr doc,
> 					 const char ** params,
> 					 const char * output,
> 					 xmlSAXHandlerPtr SAX,
> 					 xmlOutputBufferPtr IObuf)
>
> and xsltRunStylesheetUser [4]:
>
> int	xsltRunStylesheetUser		(xsltStylesheetPtr style,
> 					 xmlDocPtr doc,
> 					 const char ** params,
> 					 const char * output,
> 					 xmlSAXHandlerPtr SAX,
> 					 xmlOutputBufferPtr IObuf,
> 					 FILE * profile,
> 					 xsltTransformContextPtr userCtxt)
>
> A very unscientific search of code.ohloh.net showed these comparative
> popularities in C code:
>
> xsltApplyStylesheet [5]:      397,605
> xsltApplyStylsheetUser [6]: 2,248,197
> xsltRunStylesheet [7]:      1,113,553
> xsltRunStylesheetUser [8]:  2,659,677
>
> The two main ways to get a xsltStylesheetPtr would be
> xsltParseStylesheetDoc [9] and xsltParseStylesheetFile [10], with
> comparative popularities:
>
> xsltParseStylesheetDoc [11]:    844,622
> xsltParseStylesheetFile [12]: 4,330,439
>
> By way of comparison, newXsltCompiler gets 7,274,828 hits in Java code
[13].
>
>> From a first glance, the libxslt2 API is very closely coupled with libxml,
>> which makes it difficult to reproduce directly; in addition, my experience
>> is that an API designed for XSLT 1.0 doesn't easily scale outwards to
>> handle XPath 2.0/3.0, XSLT 2.0/3.0, XQuery 3.0, and XSD 1.1, plus
>> pipelines mixing all of the above.
>
> I don't think you could make a Saxon/C stylesheet look like a
> xsltStylesheetPtr, but it does appear that most xsltStylesheetPtr are made
> straight from a file or an existing xmlDoc, so I am back to my assertion
> that you could get a long way by the XSLT processor just producing and
> consuming xmlDoc even if, as you say, you have to reserialise from and to
> the xmlDoc to get things to work.
>
> Regards,
>
>
> Tony Graham                                   tgraham@xxxxxxxxxx
> Consultant                                 http://www.mentea.net
> Mentea       13 Kelly's Bay Beach, Skerries, Co. Dublin, Ireland
> --  --  --  --  --  --  --  --  --  --  --  --  --  --  --  --
>    XML, XSL-FO and XSLT consulting, training and programming
>       Chair, Print and Page Layout Community Group @ W3C
>
> [1]
> http://www.xmlsoft.org/XSLT/html/libxslt-transform.html#xsltApplyStylesheet
> [2]
>
http://www.xmlsoft.org/XSLT/html/libxslt-transform.html#xsltApplyStylesheetUs
er
> [3]
http://www.xmlsoft.org/XSLT/html/libxslt-transform.html#xsltRunStylesheet
> [4]
>
http://www.xmlsoft.org/XSLT/html/libxslt-transform.html#xsltRunStylesheetUser
> [5]
>
http://code.ohloh.net/search?s=xsltApplyStylesheet&pp=0&fl=C&fe=c&ff=1&mp=1&m
l=1&me=1&md=1&filterChecked=true
> [6]
>
http://code.ohloh.net/search?s=xsltApplyStylesheetUser&pp=0&fl=C&fe=c&ff=1&mp
=1&ml=1&me=1&md=1&filterChecked=true
> [7]
>
http://code.ohloh.net/search?s=xsltRunStylesheet&pp=0&fl=C&fe=c&ff=1&mp=1&ml=
1&me=1&md=1&filterChecked=true
> [8]
>
http://code.ohloh.net/search?s=xsltRunStylesheetUser&pp=0&fl=C&fe=c&ff=1&mp=1
&ml=1&me=1&md=1&filterChecked=true
> [9]
>
http://www.xmlsoft.org/XSLT/html/libxslt-xsltInternals.html#xsltParseStyleshe
etDoc
> [10]
>
http://www.xmlsoft.org/XSLT/html/libxslt-xsltInternals.html#xsltParseStyleshe
etFile
> [11]
>
http://code.ohloh.net/search?s=xsltParseStylesheetDoc&pp=0&fl=C&fe=c&ff=1&mp=
1&ml=1&me=1&md=1&filterChecked=true
> [12]
>
http://code.ohloh.net/search?s=xsltParseStylesheetFile&pp=0&fl=C&fe=c&ff=1&mp
=1&ml=1&me=1&md=1&filterChecked=true
> [13]
>
http://code.ohloh.net/search?s=newXsltCompiler&pp=0&fl=Java&mp=1&ml=1&me=1&md
=1&ff=1&filterChecked=true


Current Thread
Keywords