[Qgis-user] Qgis-server recompute always the layer bbox ?

[Marco Hugentobler]

Hi Andrea, Giovanni

QGIS Server doesn't calculate the bbox itself, but it queries the extent 
from the layers. So it can be that certain providers calculate the bbox 
(of course only if the layer / capabilities document is not cached).

For a faster startup, having a persistent cache as Giovanni suggested 
might help.

Regards,
Marco

On 14.02.2014 10:18, G. Allegri wrote:
>
>
>     I don't understand why the qgis-server eed to calculate always the
>     bbox.
>     In the server project windows,
>     qgis ask for the published bbox.
>     Why it don't use it as bbox rather than calculate it on every
>     request ?
>
>
> Marco, correct me if I'm wrong.
> QGIS Server doesn't calculate the BBOX, it parses the layers extents 
> from the .qgs project and then combine them to obtain the entire BBOX.
> The only operation it does is reprojecting the extents to WGS84 to 
> create the EX_GeographicBoundingBox element.
>
> Anyway, in case the project advertises and extent, the combined extent 
> won't be calculated, so in your case this phase shouldn't be the 
> bottleneck...
>
> giovanni
>
>
>
>
>     The FastCGI don't help really.
>     In a publishing environment every few hour the instances are
>     restated to removed zombi process.
>     This mean that every few hours the FastCGI are emptied and reloaded.
>     A fastcgi environment mean to load 20 instances of QGIS-server and
>     every of them do them own elaboration .
>     As the bbox calculation for every layer.
>
>     GASP.
>     The start could ask about one hours and more.
>
>     Also another problem with the fastcig is that when
>     I change something on a project I need to restart to Web instances
>     to dismiss the actual project and reload the new.
>
>     So every change in a qgis project need a restart of all proccess
>     (20 and so on in a fastcgi enviroment) every with a slow bbox
>     calculation phase.
>
>     mmhh...
>
>     :/
>
>
>
>     2014-02-14 9:13 GMT+01:00 G. Allegri <giohappy at gmail.com
>     <mailto:giohappy at gmail.com>>:
>
>
>
>
>         2014-02-14 Marco Hugentobler <marco.hugentobler at sourcepole.ch
>         <mailto:marco.hugentobler at sourcepole.ch>>:
>
>             Hi Andrea
>
>
>             >I suspect that QS try always to recalc the box of every
>             layer.
>
>             QGIS server caches layers (up to 100, but that can be
>             enhanced using the environment variable
>             MAX_CACHE_LAYERS).  Furthermore, the GetCapabilities
>             documents are cached (so no recalculation if using FastCGI).
>
>
>         Thanks Marco, you confirmed what I told Andrea.
>         It would be a good enhancement if caching could be done in a
>         persitent manner (out of memory). We could consider, in the
>         future, to use memcache or something similar.
>
>         giovanni
>
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>
>
>
>
>     -- 
>     -----------------
>     Andrea Peri
>     . . . . . . . . .
>     qwerty àèìòù
>     -----------------
>
>
>
>
> -- 
> Giovanni Allegri
> http://about.me/giovanniallegri
> Twitter: https://twitter.com/_giohappy_
> blog: http://blog.spaziogis.it
> GEO+ geomatica in Italia http://bit.ly/GEOplus


-- 
Dr. Marco Hugentobler
Sourcepole -  Linux & Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee

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