[PW-dev] Re: [Perl-widget-developer] XML in general

[Jay L. <Ja...@La...>]

I think we can all safely say that XML is an application developer's choice
and won't be part of the core Widget development effort - but rather an
important
side project if people want to use XML to create and control widgets.

Agreed?

Jay

> My initial reaction is that I think this is much more complex than a
widget
> library that produces HTML and it's even less clear to me that XML is a
> good delivery mechanism for abstracting forms.
>
> I truly believe that when you make an app into an HTML app vs a WML app vs
> anything else that the screens are significantly different.
>
> I think that this XML stuff may be fine for content sites like newspapers,
> but for an app it seems like it's a lot of work for much less gain than
you
> get on the pure content management side.
>
> Later,
>     Gunther
>
> At 10:49 PM 6/8/2001 +0100, Matt Sergeant wrote:
> >Thought this might interest some of you widget geeks :-)
> >
> >--
> ><Matt/>
> >
> >     /||    ** Founder and CTO  **  **   http://axkit.com/     **
> >    //||    **  AxKit.com Ltd   **  ** XML Application Serving **
> >   // ||    ** http://axkit.org **  ** XSLT, XPathScript, XSP  **
> >  // \\| // ** mod_perl news and resources: http://take23.org  **
> >      \\//
> >      //\\
> >     //  \\
> >
> >---------- Forwarded message ----------
> >Date: Fri, 8 Jun 2001 22:40:56 +0100 (BST)
> >From: Matt Sergeant <ma...@se...>
> >To: AxKit Users Mailing List <axk...@ax...>
> >Subject: XSP PerForm taglib
> >
> >Taking a bunch of ideas from a number of places I've started putting
> >together what I call the "PerForm" taglib. This is sort of a magic form
> >tag library that will enable you to write web forms sucking data from
> >various sources more easily.
> >
> >I'm looking for some sort of feedback on this, though it's pretty funky
as
> >it stands IMHO.
> >
> >Best way to describe it is with an example (this assumes passing
> >familiarity with XSP):
> >
> >===============
> >
> ><?xml version="1.0"?>
> ><xsp:page
> >     xmlns:xsp="http://apache.org/xsp/core/v1"
> >     xmlns:web="http://axkit.org/NS/xsp/webutils/v1"
> >     xmlns:f="http://axkit.org/NS/xsp/perform/v1"
> >     language="perl"
> >     indent-result="yes"
> > >
> ><!-- TOP LEVEL LOGIC -->
> ><xsp:logic>
> >
> ># Each function recieves a $ctxt object, which is a hash to
> ># store things in. It has one entry by default, "Form", which
> ># is a hash of form values
> >
> >sub load_title {
> >     my ($ctxt, $default, $current) = @_;
> >     warn("load_title ($default, $current)\n");
> >     return $current || $default;
> >}
> >
> >sub load_link {
> >     my ($ctxt, $default, $current) = @_;
> >     warn("load_link ($default, $current)\n");
> >     return $current || $default;
> >}
> >
> >sub save_title {
> >     my ($ctxt, $new_value) = @_;
> >     warn("save_title : $new_value\n");
> >}
> >
> >sub save_link {
> >     my ($ctxt, $new_value) = @_;
> >     warn("save_link : $new_value\n");
> >}
> >
> >sub start_form_create {
> >     my ($ctxt, $save_mode) = @_;
> >     warn("start_form\n");
> >}
> >
> >sub end_form_create {
> >     my ($ctxt, $save_mode) = @_;
> >     warn("end_form\n");
> >     # if everything is OK, and we're in save_mode, redirect.
> >     if ($save_mode) {
> >        if ($ctxt->{OK}) {
> >          # note mixing taglibs and Perl!!!
> >          <web:redirect uri="everything_ok.xsp"/>
> >        }
> >     }
> >}
> >
> ></xsp:logic>
> >
> >Title:
> >Link:
> ></xsp:page>
> >
> >===============
> >
> >OK, hopefully that hasn't confused anyone too much. Now the idea is that
> >these forms always get submitted back to themselves. They do their own
> >validation. If everything went well and the form got saved OK, they issue
> >a redirect to another page. It's kinda like the MVC model, only slightly
> >spiced the AxKit way :-)
> >
> >Now when the form is first loaded, the input fields are populated by a
> >callback to the load_<name>() function, where <name> is the name entry of
> >the particular form field. So to populate the first textfield, it calls
> >load_title(...). It passes in parameters $ctxt, $default, and $current.
> >Note that $current will only be filled if this form has already been
> >submitted once (filled with the current value, obviously). The value you
> >return is what goes in the text box that the user sees.
> >
> >When the form is submitted, the save_<name>() functions are called. This
> >time they are passed the $ctxt and the new value. There you can do
> >validation or whatever you like (save to a DB, etc).
> >
> >Each view of the form is started by a call to start_form_<name>(), where
> ><name> this time is the name attribute on the form. When all the form's
> >callbacks have been performed, the end_form_<name>() callback is called.
> >
> >The $ctxt object is a simple hashref that you can fill with whatever you
> >like. It's there to help you maintain state between the callbacks. It
> >contains one entry by default, "Form", which is a hashref to all the
other
> >form values. This allows you to do validation where one value depends on
> >another.
> >
> >If you *don't* want to supply callbacks for load_*, then it defaults to
> >using either the current value (i.e. the value last posted to the form),
> >or the default value specified if this is the first load of this form.
> >
> >Now when all this has been done, it doesn't generate a HTML widget. It
> >just generates some XML decorated with all the relevant attributes. You
> >need to write an XSLT stylesheet (which I'll include with the package for
> >HTML) to render it to HTML. But it's really simple to do that with
> >xsl:include/xsl:import. I may even be persuaded to do an XPathScript
> >stylesheet for it :-)
> >
> >I welcome your feedback on this. I think it will make building complex
> >forms really easy. One nice thing with XML is we can put all that nasty
> >callbacks code in another file, and use entities to load it in. Or we can
> >use "use OtherPackage qw(...)" to import the functions to the current
> >namespace. Either way will work.
> >
> >I can put this in CVS if people want to play with it as it stands. But I
> >have only implemented the textfield widget as yet.
> >
> >--
> ><Matt/>
> >
> >     /||    ** Founder and CTO  **  **   http://axkit.com/     **
> >    //||    **  AxKit.com Ltd   **  ** XML Application Serving **
> >   // ||    ** http://axkit.org **  ** XSLT, XPathScript, XSP  **
> >  // \\| // ** mod_perl news and resources: http://take23.org  **
> >      \\//
> >      //\\
> >     //  \\
> >
> >
> >---------------------------------------------------------------------
> >To unsubscribe, e-mail: axk...@ax...
> >For additional commands, e-mail: axk...@ax...
> >
> >
> >
> >_______________________________________________
> >Perl-widget-developer mailing list
> >Per...@li...
> >http://lists.sourceforge.net/lists/listinfo/perl-widget-developer
>
> __________________________________________________
> Gunther Birznieks (gun...@eX...)
> eXtropia - The Open Web Technology Company
> http://www.eXtropia.com/
>
>
> _______________________________________________
> Perl-widget-developer mailing list
> Per...@li...
> http://lists.sourceforge.net/lists/listinfo/perl-widget-developer
>