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From Michael Melhem <>
Subject RE: [PROPOSAL] Pipeline hints (fwd)
Date Fri, 06 Sep 2002 09:29:41 GMT
On Fri, 6 Sep 2002, Carsten Ziegeler wrote:

> > -----Original Message-----
> > From: Sylvain Wallez []
> > Sent: Friday, September 06, 2002 10:16 AM
> > To: Michael Melhem;
> > Subject: Re: [PROPOSAL] Pipeline hints (fwd)
> >
> >
> > Michael Melhem wrote:
> >
> > >Hi Guys,
> > >
> > >Has there been any consensus about the "pipeline-hint" stuff ? I know
> > >that Carsten has had some resversations about it?
> > >
> > >
> >
> > Carsten, you were on vacation when this was discussed, and there was no
> > real feedback on this proposal.
> >
> > I think cache points are a good thing and can greatly improve
> > performance in applications where the same data is presented in various
> > formats (e.g. html/excel/pdf). However, I'm in favor of *explicit*
> > cachepoints as automatic cache points can IMO lead to over-caching,
> > which may in fact lead to degraded performances.

FYI, at the moment, the automatic caching-point feature can be
switched on/off in the sitemap where the pipeline component is configured.
> >
> > Also, I proposed the new "pipeline-hints" attribute in replacement of
> > Michael's "cachingpoint" attribute proposal, as I didn't like to alter
> > the sitemap syntax with attributes specific to a particular pipeline
> > implementation.
> >
> > What's your opinion ?
> Difficult. Somehow, I don't like it - but it's more a feeling, so...
> Actually, I don't like explicit statements for caching and I'm in favour
> of automatic caching without any admin interaction.
> But, I agree that with this caching point behaviour, automatic is not
> the best solution, so interaction is required. Sigh.
> But, I don't like to extend the sitemap language with specific markup
> for one specific component. So a more general approach, like Sylvain
> suggested seems to be better.
> If this is modelled as an element in the sitemap, the impact on performance
> should be zero, right? If it is a special attribute, then at various places
> there need to be checks for this attribute, decreasing performance.
> I know, that this performance decrease is not very much especially compared
> to parsing XML, but I want to make everything as fast as possible.
> Because I currently don't need the caching points, so I don't want to have
> any impact on performance if I don't use them - that's my main concern.

Reagrding performance and the current patch. The "Hint" param
is set up when the tree nodes are built. AFAIK this would mean that 99%
of all the requests will have no (or very little) performance hit
at all because no check is done (besides the extra call to
buildParameters()).  The hintParam is simply passed on as an argument
to the pipeline just as params is.

Besides, pipeline-hints are a generic feature (not specfic to
caching-points) designed to make it easier to extend pipeline behavior.
So in theory ;-) whatever performance hit there maybe is not related
to whether one currently has the need for caching-point or not.
(hmmmm...I think im sounding like a lawyer)

Michael Melhem

> Hmm, I think my explanaition is not very clear, but I hope you can get what
> I mean.
> And now you...
> Regards
> Carsten

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