Re: [xsl] Presentation vs content.

Subject: Re: [xsl] Presentation vs content.
From: "Tangi Vass" <tangivass@xxxxxxxxxxxxxx>
Date: Mon, 15 Jan 2001 19:12:24 +0100
> Please bear if you find this offline :)

>From my point of view, it would be a pity if architectural issues may be
considered offline here ;-)

> I always wonder if it makes sense to use XML in the presentation layer.
> I mean .. what are the situations when this sounds plausible.

You're often looked at with big eyes when you say that, despite its shameful
"stylesheet" origin, XSLT is best used out of the presentation layer ;-).

> How is the XML/XSL combination trying to replace the long standing HTML.
> I do understand the flexibility XML gives in defining your own tags .. but
> does the necessity of doing so really arise.
> I am in a dilemma wether I am stretching (using my cocoon processor in
> between ) just for the sake of it.

With XML/XSL, you have to reverse-engineer the HTML "templates" provided by
designers to split them into the different XSL "templates". The situation is
even worse if you want to use FO!

> Also, XML sounds more good (to my understanding) as a rather terrific way
of
> data handling and transportation with XQL,XSP and similar technologies
> supporting it.

Sure!

> Conversion of the XML documents to various formats PDF, XSL etc etc via
> stylesheets sounds sweet :)

Only if you can write FO code manually without having to conform strictly to
an HTML template.

> But in the presentation layer eh !?!?
>
> Well .. now certain of my answers for the presentation layer might be
> dynamic on-the-fly XML. But this can always  be achieved thru JSP/JDBC
> combination.
> Is there somekind of memory usage angle here which gives the swing in
favor
> of XML??

The real strength of XML/XSLT compared to JDBC/JSP, from my point of view,
is paradoxally the SPEED: if you cache DOM trees, cache HTML results, set
dependencies between the entries of your cache (a bit like the unix make
command does), you achieve the performance of a static page for the most
requested ones and still an excellent one for the others, as XSL
transformations on DOM trees are quite fast.

> Also, finishing off with a last Q ..... if I were to ask you to build a
> website with a rather good UI ... which would you go in for XML/HTML.

It depends on the expected load, on the number of dynamic pages, ... No
unique answer :-(

> Please do answer asap ... lest I may go back to my HTML/JSP combination
for
> the presentation layer.

The XSL community is not very interested in caching issues, maybe because
many of its members come from Electronic Document Management, a sector where
performance has never been critical, anything being faster than a manual
work.
I think it's a mistake: XSLT is a marvellous language and I regret its bred
bad reputation in terms of performance.
It would be easier for you to stay with JSP if you're working on dynamic
pages that can't be built in batch mode... unless you have time to add
caching features to an existing processor like I did. Sorry for not being
able to share my work: I'm paid for it.

Tangi Vass





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