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From Stefano Mazzocchi <stef...@apache.org>
Subject Re: [C2] (hopefully) last sitemap major changes
Date Wed, 05 Jul 2000 17:53:43 GMT
> > My idea is:
> >
> > 1) if you ask for the resource, the tracing is lost
> > 2) if you ask for the trace, the resource is lost
> 
> Well, may be you are so kind to show it in an example especially for me (I'm sometimes
sooo
> slowly) . I didn't found one in the working draft. I see that if an error occurs then
the turn is
> to the <handle-error> automatically, but how do I request the trace? As I've understand
it, it's
> not the same as a view which I _can_ request.

Ok, let's take one step back:

1) "tracing" and "error" are not Cocoon views.

Why? because you can trace or have errors in all views. 

"Tracing" and "error" should be considered "metaviews": views of views.
This is why they deserve their own special location in the sitemap
schema.

NOTE: metaviews are recursive. You can have errors in the error metaview
and so on. But these meta-meta-events will be considered just as
exceptions and logged like any internal runtime error. Tracing or
tracing makes no sense.

2) "tracing" and "error" have different lifecycles.

While tracing is always there, errors might or might not happen at
runtime.

Another big difference is that while tracing always exists no matter
what, errors exist only if the resource doesn't exist.

The "error" metaview is mutually exclusive with any resource view. This
simplifies our job (since we have only one stream back to our client):
"aut aut" (latin for "this or that, exclusive").

The "tracing" metaview is _not_ mutually exclusive. In fact, it's always
present in every resource (it adds another dimension, topologically
speaking).

So, we must indicate when we want to access it, but we can't use the
view method.

Well, I propose we keep using URI parameters and we introduce a default
one for having access to the tracing metaview

  http://host/path/resource?cocoon-trace

NOTE: the fact that tracing is not a view but a metaview allows you to
do

  http://host/path/resource?cocoon-view="whatever"+cocoon-trace

to have access to the trace of the "whatever" view of the requested
resource.

Hope this is clear enough, now.

Any comment, suggestion, flame?

-- 
Stefano Mazzocchi      One must still have chaos in oneself to be
                          able to give birth to a dancing star.
<stefano@apache.org>                             Friedrich Nietzsche
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