On Thu, 18 May 2000, Shawn McKisson wrote:
Coimments are interspersed.
> The problem with using JSP for generating XML is that the JSP wants to
> assume that it is sitting at the top level of your application, i.e. it
> wants to send the response back to the client.
It does? Funny, I use JSP to generate XML all the time, and it goes
through XSL on the server...
> >From what I understand, your current architecture looks like this
>
> [db] <-----> [pl/sql] ---XML---> [XSL engine] --HTML via HTTP---> [client]
>
> If we try to introduce JSP into this scenario we get
>
> [db] <-----> [pl/sql] ---data---> [JSP] ---XML via HTTP--> [client]
>
> There is no room after the JSP layer to perform the XSL transformation
> JSP does not allow for post processing of it's output in order to perform
> the rendering. I believe this is because JSP is meant to be used in as
> presentation generation language, not as a data mapping language. Sure, you
> could chain this to another servlet which contained your rendering code, but
> it is much cleaner to just have something like
>
> [db] <-----> [pl/sql] ---data---> [XML data mapping code] ---XML--> [XSL
> engine] --XML/PDF/etc. via HTTP--> [client]
>
> It is the requirement that JSP respond to the client that limits its
> usefulness in this context.
Um, maybe you should switch to a better app server, one that allows
chaining based on mime types. As stated, I use a design something like
this:
[db] --data--> [beans] --> jsp --XML+XSL--> HTML
The XSL can be active content itself, so the HTML is variable (I just
haven't used it for anything else.
BTW, example content can be found at http://www.orionsupport.com/ - don't
let the file extensions fool you, it's all JSP, XML, XSL.
> --shawn
>
> ----- Original Message -----
> From: Daniel Lopez <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, May 18, 2000 1:32 AM
> Subject: Re: JSPs and XML.
>
>
> > Hi Shawn,
> >
> > We are doing something very similar, and we might as well use JSP later
> > down the road so I'll get you my own reasoning.
> > Why? Because that way you have the data generated by your action
> > completely independent of the way you present the data. So independent
> > that you don't have to use Java to format this data or even produce it.
> > For example, right now we skipped the JSP part because we are generating
> > the XML directly from PL/SQL but if we have to add some operations that
> > will be done better in Java (handling files...) we just need to produce
> > XML from Java and use the same XSLT sheets as the PL/SQL operations. Our
> > grahical designer won't even know if we are performing the logic in
> > PL/SQL or Java. And you might ask then why use JSP instead of generating
> > XML directly from servlets. Well, for the same reason we generate HTML
> > through JSP instead of generating it directly from servlets, to make the
> > result independent of the classes that implement it, easier to produce
> > without getting into the code...
> > Another reason why one would want to generate XML from JSP would be to
> > be able to forward this result to diferent XSLT and produce WML, HTML,
> > ... using the same functionality but with diferent XSLT.
> > I understand that one might think, why add such an overhead... Again,
> > JSPs are supposed not to be such an overhead because they are compiled
> > into servlets the first time you access them (you might even precompile
> > them sometimes) so they are more like a different way of specifying your
> > output.
> >
> > So, IMHO, if you are just producing HTML, you are just performing your
> > operations in Java and you don't have a designer that can play XSLT,
> > then there's no need to go for XML. But if you want to produce different
> > ouput formats reusing the same functionality, you need to seamlesly
> > integrate different sources of the information into your HTML layer or
> > you have a designer that can play XSLT then you can get some advantages
> > by using XML and you might want to produce it from Java through JSP.
> >
> > Just my 2ec
> > Dan
> > -------------------------------------------
> > Daniel Lopez Janariz ([EMAIL PROTECTED])
> > Web Services
> > Computer Center
> > Balearic Islands University
> > -------------------------------------------
> >
> >
> > Shawn McKisson wrote:
> > >
> > > Why would you want to take data, convert it into another form of data
> and
> > > *then* convert it into HTML?
> > >
> > > This is like pouring yourself a cold beer by first pouring it from the
> > > bottle into one mug, then pouring that mug into another mug.
> > >
> > > If a you have a JSP page which does emit XML, you could chain the output
> of
> > > that page through another servlet which performed the XML/XSL
> conversion. So
> > > the XML/XSL servlet would use the JSP page as a data source.
> > >
> > > There were some really good articles about 7-12 months ago on
> XML-INTEREST
> > > about this.
> > > If I can find them I will mail them to you.
> > >
> > > --shawn
> > >
> > > ----- Original Message -----
> > > From: Robert Nicholson <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Wednesday, May 17, 2000 5:10 AM
> > > Subject: Re: JSPs and XML.
> > >
> > > > I would like to know if a JSP app emits XML what component of existing
> > > > application servers can translate that to whatever presentation
> language
> > > is
> > > > prefered? I want to understand how XSLT fits into a JSP app's
> > > architecture.
> > > >
> > > > ----- Original Message -----
> > > > From: "Shawn McKisson" <[EMAIL PROTECTED]>
> > > > To: <[EMAIL PROTECTED]>
> > > > Sent: Tuesday, May 16, 2000 9:15 PM
> > > > Subject: Re: JSPs and XML.
> > > >
> > > >
> > > > > Just return XML tags instead of only HTML tags.
> > > > > There is nothing special that needs to be done.
> > > > >
> > > > > If you are going to just turn around and reprocess the XML into HTML
> > > using
> > > > > something like XSL, then you are basically needlessly supporting two
> > > > > presentation layers. You should reconsider your app architecture.
> > > > >
> > > > > --shawn
> > > > >
> > > > > ----- Original Message -----
> > > > > From: Bilal Ali Nawaz <[EMAIL PROTECTED]>
> > > > > To: <[EMAIL PROTECTED]>
> > > > > Sent: Tuesday, May 16, 2000 1:36 AM
> > > > > Subject: JSPs and XML.
> > > > >
> > > > >
> > > > > > hi all,
> > > > > > can anyone please direct me to some useful resources on the web
> > > > concerning
> > > > > how
> > > > > > to output XML through a JSP? basically what i want to study is
> that
> > > can
> > > > > XML be
> > > > > > 'thrown' by a jsp just like HTML? and if so, how??
> > > > > >
> > > > > > thanking all of you in advance,
> > > > > > bilal.
> > > > > >
> > > >
> _________________________________________________________________________
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