Ciao Andrea,
I think your idea of caching features is very very interesting. I
personally need something like that for the ImageMosaic plugin in
order to handle very large mosaic. As of now the index for the mosaic
is kept inside a shapefile and it is cached in memory using an SRTREE
JTS index held by a SoftReference, a very basic caching mechanism.
Usually this approach is good when the index is not too big
(10000-30000 images) but it becomes cumbersome when the index is
really big and I can tell you that I have seen mosaics that are
terabytes large.

Now, I have a general interest for caching both for features and
coverages therefore I am trying to see if we can find common points
between the two problems.


Commenting what Andrea said, I think he drew a very complete picture
of the situation and of the possible solutions. My suggestion for the
moment is starting with something not too complicated, much probably a
read-only cache that just unload the cache when changes are made to
the data because where we really need speed (==caching) is WMS (which
is read-only) . Of course having listeners notifying us would be much
better.

Thinking about how to hold objects. My experience is  as follows:

-never use weak references, they got cleaned up almost instantaneously
-be careful when using softreferences, they got cleaned up pretty
quickly unless you know how to control them
-be careful with hard references, you are in control of releasing them

For this kind of cache the choice is between soft and hard references,
but I would rather see using hard references  with control over the
memory size used by the cache (much like the JAI TileCache).


For the moment this is enough, I hope someone else will share some
thoughts on this because having caching inside GeoServer would speed
it up a lot.

Simone.

On 10/7/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Justin Deoliveira ha scritto:
> > Can we have a link to the page :).
> >
> What?! Can't you use Google? :-p
> Seriously, sorry, I was in a hurry and forgot to add the link:
> http://docs.codehaus.org/display/GEOTOOLS/Datastore+caching
>
> Cheers
> Andrea
>
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-- 
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Eng. Simone Giannecchini
President /CEO GeoSolutions

http://www.geo-solutions.it

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