[Users] Fwd: GeoExt.LegendPanel too slow with too many sublayers

[Vito Meuli]

Hi List! Hi Andreas!
Thank your help, and with a big effort in optimizing everything, now my maps and my legend are faster and satisfactory.

I can suggest what follows about Mapserver mapfiles for WMS:
* try to have the lesser LAYERs you can - use many CLASSes in a single LAYER if you can (keeping an eye to overlapping geometries!)
* keep your mapfiles not longer then 20 LAYERs; better many short mapfiles then a single, long one.

I still have to try a web server cache, but now I can't afford the time needed to understand and tune it: it is really promising.
It seems it will be not so simple with just a mod_cache in Apache2, though.

I'll let you know when the new, fast version will be online, if you want to see the differences with the old, slow one.

Cheers,
Vito


----- Messaggio originale -----
Da: "Vito Meuli" <v.meuli at tecnologieavanzate.it>
A: "Andreas Hocevar" <ahocevar at opengeo.org>
Cc: "GeoExt Users" <users at geoext.org>
Inviato: Mercoledì, 12 maggio 2010 16:51:34 GMT +01:00 Amsterdam/Berlino/Berna/Roma/Stoccolma/Vienna
Oggetto: Re: [Users] Fwd: GeoExt.LegendPanel too slow with too many sublayers

Hi!

Yes, Andreas, you are right.
We use so many LAYERs because of transparencies: Mapserver (maybe every GIS) cannot deal overlapping geometries in different CLASSes inside the same LAYER; without a proper analisys of data we had no choice: write a LAYER per CLASS.

The result is not reasonable (too slow), so now a colleague of mine is performing such a (long) data analisys.

Another bad practice of mine has been stuffing all of such LAYERs inside a single mapfile: this explains why the server is so slow in creating a response for GetLegendGrapghic (from 2s to 4s!!!).
Now I'll separate LAYERs in a few different mapfiles, so I expect another little performance boost.

Last but not least, I'm looking for a cacheing mechanism in the web server: maybe Apache is enough for that.

As usual, problems teach you a lot more :-)

Thank you very much for you help!
Regards,
Vito

----- Messaggio originale -----
Da: "Andreas Hocevar" <ahocevar at opengeo.org>
A: "Vito Meuli" <v.meuli at tecnologieavanzate.it>
Cc: "GeoExt Users" <users at geoext.org>
Inviato: Martedì, 11 maggio 2010 18:08:22 GMT +01:00 Amsterdam/Berlino/Berna/Roma/Stoccolma/Vienna
Oggetto: Re: [Users] Fwd: GeoExt.LegendPanel too slow with too many sublayers

Hi,

everything I see in your demo works as expected. Your servers, however, respond very very slowly.

Your sublayers are not exposed to the layer tree. I see you are using Mapserver. Why don't you just create CLASSes instead of LAYERs for e.g. road categories?

Regards,
Andreas.

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ing. Vito Meuli
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