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

G. Allegri giohappy at gmail.com
Fri Feb 14 02:11:28 PST 2014


Marco, for the root I thought the OWS setting was used [1], while it isn't
for the groups/layers childs [2]. Is it right?

giovanni

[1]
https://github.com/qgis/QGIS/blob/master/src/mapserver/qgsprojectparser.cpp#L138
[2]
https://github.com/qgis/QGIS/blob/master/src/mapserver/qgsprojectparser.cpp#L980


2014-02-14 Marco Hugentobler <marco.hugentobler at sourcepole.ch>:

> Hi Bernhard
>
> That option was meant to give the webclient a hint where to zoom first.
> But it probably was forgotten in the server and I agree it would be good to
> overwrite the calculated box in the toplevel group.
>
> Regards,
> Marco
>
>
> On 14.02.2014 10:58, Bernhard Ströbl wrote:
>
>> Hi Marco,
>>
>> I have a question in this context (I thought I made ticket but cannot
>> find it)
>> What is the sense of setting the bounding box in OWS tab if it is always
>> calculated to the sum of the bboxes of the layers in the project? IMHO
>> setting the bbox in the project properties should override any calculation
>> result.
>> Background: One of my layers became empty because a user deleted the last
>> record thus its bbox was calculated to be the whole earth resulting in QGIS
>> server propagating the whole earth as bbox for this project.
>>
>> Bernhard
>>
>> Am 14.02.2014 10:34, schrieb 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
>>>>
>>>>         _______________________________________________
>>>>         Qgis-user mailing list
>>>>         Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
>>>>         http://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>
>>>>
>>>>
>>>>
>>>>     --
>>>>     -----------------
>>>>     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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>>
>
> --
> 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
>
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/qgis-user
>



-- 
Giovanni Allegri
http://about.me/giovanniallegri
Twitter: https://twitter.com/_giohappy_
blog: http://blog.spaziogis.it
GEO+ geomatica in Italia http://bit.ly/GEOplus
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