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RE: external functions: prior art in Qexo

From: Kay, Michael <Michael.Kay@softwareag.com>
Date: Wed, 15 Jan 2003 12:58:02 +0100
Message-ID: <DFF2AC9E3583D511A21F0008C7E621060453DF45@daemsg02.software-ag.de>
To: Per Bothner <per@bothner.com>, public-qt-comments@w3.org

You may be aware that XSLT 1.1 attempted to define a standard API for
calling Java methods as external functions from XSLT. The result of these
efforts is at http://www.w3.org/TR/xslt11/

The work was abandoned because it ran into too much resistance. There were
objections to the idea that the WG should define interfaces for some
languages and not others, and there were problems in defining the semantics,
for example when calling methods with side-effects.

I still think it would be a good idea to have such a spec, allowing a
greater degree of interoperability between those implementations that
support a Java interface, but it would probably have to be done outside W3C.

Of course XSLT will retain the notion that the language is capable of
calling external functions, while leaving all the details of the language
binding to the implementor.

Michael Kay
Software AG

> -----Original Message-----
> From: Per Bothner [mailto:per@bothner.com] 
> Sent: 15 January 2003 04:02
> To: public-qt-comments@w3.org
> Subject: external functions: prior art in Qexo
> 
> 
> 
> Various issues (possibly 124 157 223 272 317) discuss the 
> need for being able to call "external functions".  This page: 
> http://www.gnu.org/software/qexo/Extensions.html#Calling-Java-Methods
> explains how Qexo allows XQuery functions to call arbitrary 
> Java methods.  Of course this mechanism is too Java-specific to be 
> standardized (though similar mechanisms should work for other 
> languages).  However, possibly Java implementors come agree 
> some something that could be a non-normative addendum.
> 
> The mechanism in issue 223 is more general and robust, as it 
> allows extenrnal functions to be defined in any language, 
> including XQuery and Java.  However, it still leaves open how 
> to bind an external function to a (say Java) method.
> 
> (I make no claim for originality - XSLT implementations have 
> used similar extension mechanisms for years.)
> -- 
> 	--Per Bothner
> per@bothner.com   http://www.bothner.com/per/
> 
Received on Wednesday, 15 January 2003 06:58:11 GMT

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