Re: XSLT and external calls
> instance a CAS or a Tex2MathML converter) produces. So I was wondering if > there are ways of stil having an XSLT stylesheet (maybe with a proprietary > extension element that allows me to call specific Java methods or external There are two diametrically opposed directions here. 1. You view XSLT as just another "scripting platform" deeply embedded into your particular platform-specific system. You freely extend it using custom java extensions, VB script, C++ extensions, <script> elements and so on that perform everything from database queries to procedural nodeset processing that was too hard (or too slow) to write in XPath/XSLT. Portability between engines, platforms and applications of the mappings contained in the XSLT is irrelevant to you. If you need to talk to a database server for a lookup during the transform, you write some custom java code, and use "<myname:yourjdbc.ora sql="select * from bar">..." to access your database. 2. You think XML/XSLT points to a way for separating XML processing from platform-specific technologies, and want to be able to reuse and move it around at will. Whenever possible, you implement transforms as self-contained, reusable modules that rely on standard XSLT or well-supported "industry-standard" extensions (EXSLT). If you need to talk to the outside world to complete a transform, you try to figure out how to avoid it. If that does not work, you use a document() call to a URL -- using standard CGI-encoding of parameters. If that does not work, you use a SOAP call to make a coarse-grained web services request to your app server. You want to move to a loosely-coupled data processing architecture, expose all of your data as RESTful XML and/or web services, and finally unlock your application mappings and logic from specific platforms. If you map format X to format Y in one application, you want to reuse that mapping in all of your other applications without changes. So there's more than just a simple programming question here, it's actually a big fork in the road. Sometimes #1 is OK, but I find that more often someone wants #2, but pursues #1 "by default." In that case, like David says, document() call is preferable, especially if you are doing something relatively simple. Often you can even use an XML file for "on-the-side" lookups of things like "id->name" mappings needed for XML ETLs. For more complex queries, our engine provides a syntax for making SOAP calls from within the transform. Long-term, this too should become a standard namespace. \\ Eugene Kuznetsov, Chairman & CTO \\ eugene@xxxxxxxxxxxxx \\ DataPower Technology, Inc. - xml-aware network devices \\ http://www.datapower.com - XA35 XML Accelerator XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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