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From Allan Erskine <a.ersk...@cs.ucl.ac.uk>
Subject Re: [C2] XSP based Action (was Re: cvs commit: xml-cocoon/webapp/docs/samples/xsp cookie.xsp)
Date Thu, 19 Apr 2001 16:11:04 GMT
Here's two possible approaches:  an XSP action root element, or namespace
introduction.

With a root element, we could use that to fix what type of component gets
generated, so that <xsp:page> produces XSPGenerator components, <xsp:action
....> produces Actions.  Within the XSP action page body it should be
possible to use the other taglibs as before, as they ought to be made
agnostic as to why they're producing XML, or performing queries in esql's
case.

Namespace introduction seems to be a bit more subtle, but it was the way
some people, notably Stephano, Matt, and Ricardo, seemed to envisage things
going.  Here an XSP file needs no root element (and embedded code is
disabled without explicitly being enabled), and taglibs are brought in
through namespace introduction as appropriate eg

<?xml?>
<content>
<p xmlns:xsp-request="........">The request was <xsp-request:get-parameter
...../>
</p>
<xsp-request:get-parameter>this element gets output as is, since it's not in
the namespace scope.
</xsp-request:get-parameter>
</content>

This reflects a duality of purpose in the way almost all xsp tags are used.
On the one hand they configure some code, on the other hand they produce
some XML.  I see nothing wrong with this; it seems just a natural
consequence of wanting to produce XML dynamically.

So here taglibs would declare what interfaces they could be called through
(in cocoon.xconf), and those which didn't could be used generically (ie just
to produce XML).  We'd need at least one action specific taglib used
somewhere in an XSP file for the generated component to implement the Action
interface (and be used as an action within the sitemap).

We'd probably find most XSP components would have some XML part representing
the state of the component (in a serverpage this is the predominant part),
so for this approach I'd be tempted to extend all XSP components from
XSPGenerator, and to implement different interfaces depending on the taglibs
used within.  The semantics of generating a component other than a
serverpage would be to access the state of that component in a pipeline (for
administrative purposes say).

Of course there's probably a bit more room for confusion this way as it
breaks cohesion.

Any thoughts?  The first way seems easiest...

Allan

----- Original Message -----
From: "Davanum Srinivas" <dims@yahoo.com>
To: "cocoon-dev" <cocoon-dev@xml.apache.org>
Sent: Thursday, April 19, 2001 4:06 PM
Subject: [C2] XSP based Action (was Re: cvs commit:
xml-cocoon/webapp/docs/samples/xsp cookie.xsp)


> Allan,
> +1 for taking a shot @ XSP based actions.
>
> Thanks,
> dims
>
> --- Allan Erskine <a.erskine@cs.ucl.ac.uk> wrote:
> > > But of course we could prove if we should change the sitemap
generation
> > > for a next release, but I don't want to change it for the first C2
> > release.
> >
> > Yes, of course...Ricardo was talking about a fairly hefty overhaul of
the
> > XSP mechanism.  You're right that this shouldn't get in the way of all
the
> > great work you've been doing.  And SiLLy was also part of the plan for
the
> > new mechanism...
> >
> > In the longer term though, I think an XSP sitemap makes a lot of sense.
> >
> > What about XSP actions though?  It strikes me that they could be
implemented
> > without getting in anyone's way, and it would be a good practise ground
for
> > ramping up XSP's role in the future, if we decide that's the way to go.
> >
> > I'd be happy to muck in and help do this.
> >
> > Allan
> >
> > ----- Original Message -----
> > From: "Carsten Ziegeler" <cziegeler@sundn.de>
> > To: "cocoon-dev" <cocoon-dev@xml.apache.org>
> > Sent: Thursday, April 19, 2001 3:39 PM
> > Subject: AW: cvs commit: xml-cocoon/webapp/docs/samples/xsp cookie.xsp
> >
> >
> > > Allan Erskine wrote
> > >
> > > > -1 for XSP for sitemaps as we shouldn't change the concept at
> > > this stage.
> > > The
> > > > sitemap is working very well and you don't really have to worry
> > > about any
> > > > programming language (like Java for XSP etc) to "write" your
sitemap.
> > >
> > > AFAIR the idea was that all programming constructs in an XSP page
> > > were bad,
> > > so we'd disable it by default for all XSP components apart from
> > > serverpages
> > > (to maintain compatibility).  The sitemap syntax would remain
completely
> > > unchanged.
> > >
> > Ah, ok this changes something. If there would be no difference for the
> > sitemap writer, XSP is ok. I don't want to start the old discussion
again,
> > but I don't see any advantage in using XSP then for the sitemap as well.
> > We have a good working solution.
> >
> > But of course we could prove if we should change the sitemap generation
> > for a next release, but I don't want to change it for the first C2
release.
> >
> > regards Carsten
> >
> > > Only the sitemap generating mechanism would change.  It would become
> > > rationalised with a general purpose XSP component generation and
> > > compilation
> > > mechanism.  Ricardo was all for XSP sitemaps, and regarded it as a
blunder
> > > that they were separated (he pointed this out in the XSP and aspects
> > > thread).
> > >
> > > Allan
> > >
> > > ----- Original Message -----
> > > From: "Carsten Ziegeler" <cziegeler@sundn.de>
> > > To: "cocoon-dev" <cocoon-dev@xml.apache.org>
> > > Sent: Thursday, April 19, 2001 2:51 PM
> > > Subject: AW: cvs commit: xml-cocoon/webapp/docs/samples/xsp cookie.xsp
> > >
> > >
> > > > Allan Erskine wrote:
> > > >
> > > > > I think, this are two different tasks, the first is database
> > > access and
> > > > the
> > > > > second is redirection. For generating content, XSP Taglibs
> > > are very very
> > > > > valuable. There is no doubt about it. But I personally see XSP
> > > > (currently)
> > > > > only on the content side and not on the webapp flow (see below).
> > > >
> > > > From the thread XSP and aspects a month or two ago, Ricardo voiced
the
> > > > opinion that separating the sitemap generating mechanism from XSP
> > > > was a big
> > > > mistake, and AFAIR it was concluded that it would be advantageous if
the
> > > > sitemap were brought back under (a suitably restricted) XSP's
> > > > remit.  So XSP
> > > > should perhaps be considered for webapp flow.
> > > >
> > > > In my opinion this goes for a number of other C2 components, in
> > > particular
> > > > actions.  Implementing an XML->action compilation mechanism would
seems
> > > > ludicrous as it would invariably be XSP-like.....I would like to
> > > > view XSP as
> > > > the single canonical language for configuring and representing the
state
> > > > structure for all dynamic components in an XML server environment,
but I
> > > > don't know if this view is widely held.
> > > >
> > > > If a superior XSP processing pipeline mechanism could be
> > > implemented, then
> > > > in the first instance, sitemaps and serverpages could be
> > > generated in the
> > > > same way, work could begin on the flowmap, and actions and other
> > > > components
> > > > could enjoy from all XSP's wonderful dimensionality reducing
> > > features.  A
> > > > large majority of users have experience with tag-libs, and will be
> > > > immediately overawed by the potential of Cocoon if it became an
> > > > XSP platform
> > > > on this scale.  As it is, I agree there will be a lot of
head-scratching
> > > > going on over java actions as they stand.
> > > >
> > > > And going back to the flowmap (I think a lot of us know we want one,
but
> > > > aren't sure how to get it); if a flowmap and the sitemap were both
XSP
> > > > taglibs, people would take to the idea like ducks.  Imagine the
> > > > potential of
> > > > the flowmap guiding the application flow from state to state,
> > > with sitemap
> > > > constructs shifting the URI landscape accordingly within the same
> > > > XSP file.
> > > > <flow:this> <map:that>  Sitemap URI's wouldn't even exist
until the
> > > > application was in the correct flow-state.  To users from an XSP
> > > > background,
> > > > it would seems the most natural thing in the world to see these
> > > two hugely
> > > > powerful taglibs come together in one file.
> > > >
> > > > (Ricardo says he's been working on ideas for a component composition
> > > > mechanism which could potentially realise this sort of
> > > > application.  I hope
> > > > it wouldn't be too presumptious to suggest that he'd be very
> > > happy if more
> > > > people came round to this viewpoint)
> > > >
> > > > So my position is:  XSP for sitemaps, serverpages, flowmaps,
actions,
> > > > aspects.
> > > >
> > > +1 for XSP for serverpages
> > > +1 for XSP for actions
> > > don't know for XSP for flowmaps
> > > -1 for XSP for sitemaps as we shouldn't change the concept at this
stage.
> > > The
> > > sitemap is working very well and you don't really have to worry about
any
> > > programming language (like Java for XSP etc) to "write" your sitemap.
> > >
> > > > I have a web-app currently eating into my time (was supposed to
> > > > be finished
> > > > 2 weeks ago, all that writing java actions!) but after that I'd like
to
> > > > commit myself to just such a project.
> > > >
> > > Great, we should see how this fits to our beta release date.
> > >
> > > regards Carsten
> > >
> > >
> > > ---------------------------------------------------------------------
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> > >
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> >
> >
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> >
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>
>
> =====
> Davanum Srinivas, JNI-FAQ Manager
> http://www.jGuru.com/faq/JNI
>
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