xml-dev - RE: xslt

["Bullard, Claude L (Len)" <clbullar@ingr.com>]

Usually, articles cite repurposing (eg, getting the 
same content and JIT transforming it for different 
clients) but repurposing is a general quality of 
markup and as you note, given ASP, templates, etc, 
one can do that without XSLT.   

The surface cases for XSLT are efficiency and 
convenience:

1.  Speed.  Microsoft has published test results 
showing a speed-up of in some cases seven to one. 
Stats (as we all know by now) are subject to review. 

2.  Reuse.  In theory at least, an XSLT script should 
be reusable on different platforms.   This is a 
conformance issue.

3.  Ease.  Except for cases such as recordsets masquerading as XML 
documents (very shallow, very regular, shoulda been a 
table), it is easier to write XSLT to transform a 
document than to use say DOM and scripting calls. 
Look at comparisons of data-centric and document-centric 
models for use cases.

4.  Lexical unification - Being an XML vocabulary, it 
is easy to use the same tools to manipulate XSLT as for 
other XML languages.  Mileage varies (see item 3).
Being able to reapply XPath has advantages 
on the learning curve although the syntax of XPath isn't 
all that easy to learn.  If you come from a procedural 
background, XSLT takes some getting used to. 
 
5.  Generalized support for coarse transactions and 
persistence.   This area is murkier.  Transaction support 
has been around since the SABRE system (real early sixties) 
but overall, converging on XML makes it simpler to do 
given a stateless protocol and very wide distribution. 
Having XSLT to support this both server and client side 
simply makes it easier to write a lot of transforms against 
the same message, so integration is easier and it is simpler 
to prove that the transformation of a record of authority 
has not resulted in extra-contract changes to the semantic 
of the information.  This gets into enterprise applications 
and is a much bigger topic than we can take up here.

Len Bullard
clbullar@ingr.com
http://www.mp3.com/LenBullard

Ekam sat.h, Vipraah bahudhaa vadanti.
Daamyata. Datta. Dayadhvam.h


-----Original Message-----
From: Brian Killian [mailto:brian@bepinc.com]

Hello, I'm new to XML and these XML related technologies and I'm trying to
understand their benefits and uses.  I understand now what XML is all about
but I'm still not sure what the purpose is of using XSLT.  I know of course
that its used to transform documents, but I don't understand why it is
necessary when we have templating systems and technologies like ASP to
dynamically determine the markup that goes out to a browser.  Are there
advantages to using XSLT over other technologies that I am missing? What is
unique about it? How are other people using it and why?  Any insight about
this would be great!