RE: Re: XML stuff (was: UKHA Classified update - SQL Help!)

["BUTLER, Tony, FM" <tony.butler@xxxxxxx>]

> > You want a web page?  Transform that puppy!
> >
> But you are saying that your XLST is on the server, so in
> transforming the
> said pooch, does it entail a round trip to the server or is this all
> performed on the client?

This is how it works:
Client clicks URL
Web Server retrieves XML data set from App Server which retrieves from SQL
Server
(Traditionally, WS retrieves ADO data set from App server.....)
Web Server does the XSLT Transformation & passes a web page back to the
client.
If you can guarantee the version of the browser the client is using (ie in
an intranet - except ours :() then
Web Server passes XML & XSLT back to client and client does the work.
This means client _could_ do lots of different xforms to data without going
back to any server.
where the web server does the xform, it could cache the xml data set and
reduce round trips to the app server etc....

> > Where it has worked for me is when for instance data needs
> to be displayed
> > in a drop down combo box or a tree view - use the same data
> set from the
> > same business object (naturally!) and just XSLT it on the
> web server to the
> > appropriate format.
> Again I am reading this as happening on the server, in which
> case what does
> it offer over ASP or other server based dynamic page
> building? Is it simply
> saving another trip to the database?

It allows you to separate the data access stuff from the display stuff.
The ASP page basically consists of:
create Business Object
Call method to retrieve XML
Xform it and write out the results.

Means you don't do things like:
while not rs.eof
response.write "<option>" & rs("desc") &
"</option>"
rs.movenext
wend

ie mixing display and data access.
What if you don't want a drop down list, you want a table instead?
The display code is all mixed in with the data access & you have to
rewrite.

it's 'cleaner' with XML/XSLT

> Now you are getting into the area I am really interested in,
> how do I know
> when to use XML without having to learn it all? I am sure
> there are things

rules of thumb:
If it's recursive, XML it.
If you want to display the same data set in different ways, XML it.

Oh, and move to .net - it's even easier to do it then!

Tony


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