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RE: Application Design

• From: Alaric Snell <alaric@a...>
• To: The Deviants <xml-dev@l...>
• Date: Mon, 13 Aug 2001 16:23:27 +0100 (BST)

(As the good Mr. Champion notes, I missent this mail)

ABS

----- Forwarded message from Mike.Champion@S... -----
Date: Mon, 13 Aug 2001 10:13:38 -0400
From: Mike.Champion@S...
Reply-To: Mike.Champion@S...
Subject: RE: Application Design
To: alaric@a...

Hi Al,

I didn't see this on the list ... did you send it to just me by mistake?

I think it makes a VERY good point ... XSLT works if you can get away with
its built-in functions like sum() and count(), but if you need to do
something like a standard deviation, you're outta luck, or at least you're
in for an ugly time.

Mike

> -----Original Message-----
> From: Alaric Snell [mailto:alaric@a...]
> Sent: Monday, August 13, 2001 7:50 AM
> To: Mike.Champion@S...
> Subject: RE: Application Design
>
>
> Quoting Mike.Champion@S...:
>
> > > If only the world were so simple!
> >
> > So, let's make it that simple :~)  Maybe XSLT isn't what we
> really need,
> > but
> > maybe there's a subset of XSLT that hits the 80/20 point, or maybe
> > there's a
> > more elegant alternative that does what we hoped XSLT would do.
>
> I like your thinking.
>
> For web designers, I've seen their needs as a very basic
> templating language
> that is just an HTML or XML document with special elements to:
>
> 1) Insert value of (expression) here
> 2) If (condition expression) do (this) else (this)
> 3) For each value in (list expression) do (this)
>
> Those "expressions" include normal number/string arithmetic
> plus the power of
> function-calling. The usual functions are supplied with the
> core system, plus a
> few functions to query SQL databases and XML documents and so
> on. The backend
> developers ideally provide functions to handle all those
> details, but for simple
> systems and simple parts of systems, being able to go direct
> to the database
> comes in handy.
>
> The expressions are dead simple. Simpler than XPath. Easier
> to extend (XPath
> allows for extensions with namespaced functions, but there's
> no easy way to
> exploit this in the implementations I've seen). From the application
> programmer's perspective, there must be a language binding
> standard like DOM
> that explains how to invoke templates and how to set up a
> "template engine" and
> register functions in it for the template authors to use.
>
> What it definitely LACKS is templates and their matching.
> THis thing is not for
> converting DocBook into HTML. This thing is for displaying a
> page of search
> results etc. Converting DocBook into HTML is what XSLT is good at.
>
> I wrote a content management system based upon this
> architecture once and
> everyone loves using it, so it's a workable approach.
>
> > And
> > as Michael Rys pointed out, as XSLT gets embedded deep into OS or DB
> > or
> > server architectures, we start to see some serious performance
> > improvements
> > over procedural ASP/JSP/CGI/etc. alternatives.
>
> I'm real keen to know how this works and to see some figures.
> I'm sure like
> isn't being compared with like!
>
> > I'd be very interested in hearing from people who have tried to
> > implement
> > more complex XSLT applications. When does XSLT generally
> hit the wall?
>
> *shudder* There are certain kinds of computation it can't do.
> Note that it has
> sum() and count() functions, so you can do totals and
> arithmetic means, but if
> they want a standard deviation it gets a little harder all of
> a sudden. And the
> whole problem of the input XML document - in a Web
> application, the designers
> are always changing their minds about what to put on what
> page. With my
> templating system approach (that HAS no initial document,
> just functions that
> return values on demand) they get to choose what data they
> want, rather than
> having to ask the guy who writes the code that generates the
> XML data to change
> what data are there before the designers can update their
> XSLT to display said
> data.
>
> > Is
> > there an alternative (given than you have XML data as the
> input) other
> > than
> > just writing code? (For example, does anyone other than Al
> Snell find
> > PHP
> > templates to be a more powerful, easier to use alternative?)
>
> http://www.php.net/
> http://www.php.net/usage.php
>
> > How do
> > people
> > feel about XQuery's output reformatting capabilities as an
> 80/20 point
> > for
> > real-world web applications?
>
> Not yet played :-(
>
> ABS
>
> --
>                                Alaric B. Snell
>  http://www.alaric-snell.com/  http://RFC.net/
> http://www.warhead.org.uk/
>    Any sufficiently advanced technology can be emulated in software
>

----- End forwarded message -----



-- 
                               Alaric B. Snell
 http://www.alaric-snell.com/  http://RFC.net/  http://www.warhead.org.uk/
   Any sufficiently advanced technology can be emulated in software  

Hi Al,

I didn't see this on the list ... did you send it to just me by mistake?

I think it makes a VERY good point ... XSLT works if you can get away with its built-in functions like sum() and count(), but if you need to do something like a standard deviation, you're outta luck, or at least you're in for an ugly time.

Mike

> -----Original Message-----
> From: Alaric Snell [mailto:alaric@a...]
> Sent: Monday, August 13, 2001 7:50 AM
> To: Mike.Champion@S...
> Subject: RE: Application Design
>
>
> Quoting Mike.Champion@S...:
>
> > > If only the world were so simple!
> >
> > So, let's make it that simple :~)  Maybe XSLT isn't what we
> really need,
> > but
> > maybe there's a subset of XSLT that hits the 80/20 point, or maybe
> > there's a
> > more elegant alternative that does what we hoped XSLT would do.
>
> I like your thinking.
>
> For web designers, I've seen their needs as a very basic
> templating language
> that is just an HTML or XML document with special elements to:
>
> 1) Insert value of (expression) here
> 2) If (condition expression) do (this) else (this)
> 3) For each value in (list expression) do (this)
>
> Those "expressions" include normal number/string arithmetic
> plus the power of
> function-calling. The usual functions are supplied with the
> core system, plus a
> few functions to query SQL databases and XML documents and so
> on. The backend
> developers ideally provide functions to handle all those
> details, but for simple
> systems and simple parts of systems, being able to go direct
> to the database
> comes in handy.
>
> The expressions are dead simple. Simpler than XPath. Easier
> to extend (XPath
> allows for extensions with namespaced functions, but there's
> no easy way to
> exploit this in the implementations I've seen). >From the application
> programmer's perspective, there must be a language binding
> standard like DOM
> that explains how to invoke templates and how to set up a
> "template engine" and
> register functions in it for the template authors to use.
>
> What it definitely LACKS is templates and their matching.
> THis thing is not for
> converting DocBook into HTML. This thing is for displaying a
> page of search
> results etc. Converting DocBook into HTML is what XSLT is good at.
>
> I wrote a content management system based upon this
> architecture once and
> everyone loves using it, so it's a workable approach.
>
> > And
> > as Michael Rys pointed out, as XSLT gets embedded deep into OS or DB
> > or
> > server architectures, we start to see some serious performance
> > improvements
> > over procedural ASP/JSP/CGI/etc. alternatives.
>
> I'm real keen to know how this works and to see some figures.
> I'm sure like
> isn't being compared with like!
>
> > I'd be very interested in hearing from people who have tried to
> > implement
> > more complex XSLT applications. When does XSLT generally
> hit the wall?
>
> *shudder* There are certain kinds of computation it can't do.
> Note that it has
> sum() and count() functions, so you can do totals and
> arithmetic means, but if
> they want a standard deviation it gets a little harder all of
> a sudden. And the
> whole problem of the input XML document - in a Web
> application, the designers
> are always changing their minds about what to put on what
> page. With my
> templating system approach (that HAS no initial document,
> just functions that
> return values on demand) they get to choose what data they
> want, rather than
> having to ask the guy who writes the code that generates the
> XML data to change
> what data are there before the designers can update their
> XSLT to display said
> data.
>
> > Is
> > there an alternative (given than you have XML data as the
> input) other
> > than
> > just writing code? (For example, does anyone other than Al
> Snell find
> > PHP
> > templates to be a more powerful, easier to use alternative?)
>
> http://www.php.net/
> http://www.php.net/usage.php
>
> > How do
> > people
> > feel about XQuery's output reformatting capabilities as an
> 80/20 point
> > for
> > real-world web applications?
>
> Not yet played :-(
>
> ABS
>
> --
>                                Alaric B. Snell
>  http://www.alaric-snell.com/  http://RFC.net/ 
> http://www.warhead.org.uk/
>    Any sufficiently advanced technology can be emulated in software 
>

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