Re: XMLmind XSL-FO Converter : Using user-defined functions

On 06/26/2013 02:21 PM, Nicolas Dubien wrote:
>
> I am looking for an XLS-FO engine that can fit with my current
> architecture. I am already using other engines which are based on other
> technologies - not-XSL-FO. In our current architecture we are using
> user-defined functions to add our proper features to the engine.
>
> As a matter of fact, I was wondering if it is possible to integrate
> user-defined functions in my XSL-FO templates and define them in Java.
> Then your engine will call my Java function if necessary. I did not find
> any solutions to do this on your website.
>
> Here are examples of functions I would like to be able to call from your
> engine during the generation:
>   * getResourceUrl("my resource name")
>   * ChangeCase($first_name_from_xml, "Upper")
>   * GetId($first_name_from_xml, $last_name_from_xml)
>
> One of the engines I am using for the moment is FreeMarker, it has this
> feature. It allows developers to wrap their own objects and send them to
> their engine.
> cf.
> http://freemarker.sourceforge.net/docs/api/freemarker/template/Template.html#process%28java.lang.Object,%20java.io.Writer,%20freemarker.template.ObjectWrapper%29
>

XMLmind XSL-FO Converter is an XSL-FO processor. It starts its work 
after an intermediate XSL-FO file has been generated.

See "How it works": http://www.xmlmind.com/foconverter/how_it_works.html

The vast majority of our customers use an XSLT stylesheet to generate 
the intermediate  XSL-FO file.

An XSLT engine (which interprets the XSLT stylesheet) such as Saxon 6 
very easily supports user-defined functions written in Java.

See Saxon 6's "Writing extension functions": 
http://saxon.sourceforge.net/saxon6.5.5/extensibility.html#Writing-extension-functions

This is why there is absolutely no need for us to be able to execute 
calls to user-defined functions written in Java from our XSL-FO processor.

Example:

--> This is common and useful:

XSLT stylesheet:
---
<xsl:template match="html:img[@class='resource']">
   <fo:external-graphic src="{my:getResourceUrl('my resource name')}"
     xmlns:my="java:org.dubien.MyFunc.getResourceUrl"/>
</xsl:template>
---

which generates the following XSL-FO:
---
<fo:external-graphic src="url(file:/res/foo.png)"/>
---



--> This would be equivalent but more complex, not useful, and hence 
*not* supported.

XSLT stylesheet:
---
<xsl:template match="html:img[@class='resource']">
   <fo:external-graphic src="invoke(org.dubien.MyFunc.getResourceUrl('my 
resource name'))"/>
</xsl:template>
---

which generates the following XSL-FO:
---
<fo:external-graphic
   src="invoke(org.dubien.MyFunc.getResourceUrl('my resource name'))"/>
---

which would be then evaluated by XMLmind XSL-FO Converter as:
---
<fo:external-graphic src="url(file:/res/foo.png)"/>
---


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