[QGIS-Developer] QGIS WMS provider firing too many requests !?
Jeff McKenna
jmckenna at gatewaygeomatics.com
Sat Feb 13 10:45:15 PST 2021
Hi Richard,
Yes I've noticed this also, I just never spent time to examine why. For
example, using my own WMS service I zoomed in and QGIS fired 11 GetMap
requests to my server. It's difficult to trigger though (I can't
reproduce with your NL service). Bizarre. But I have definitely seen
9+ GetMap requests for the same service/layer.
-jeff
--
Jeff McKenna
GatewayGeo: MapServer Consulting and Training Services
co-founder of FOSS4G
http://gatewaygeo.com/
On 2021-02-13 11:29 a.m., Richard Duivenvoorde wrote:
> Hi,
>
> As a vivid WMS user/debugger, I see that QGIS is firing 9 requests per 'view-extent' currently.
>
> I'm aware of cache etc etc... but... especially when using temporal filters for example, do others agree with me that this is more or less useless?
> I'm also aware that a lot of WMS are actually just WMS interfaces in front of a cached WMTS, but still.
>
> - some (governmental) services nowadays are still free for fair use, but: firing 9 times the actual requests costs resources/energy/maybe money
> - before the WMTS I ran WMS services sometimes with pretty heavy styling, so on higher zoomlevels you do NOT want your clients to fire 9 requests, and just effectively use 1 ...
>
> So in short: should I try to add some kind of (hidden?) option to minimize the number of requests?
>
> To test a wms of all municipalities of NL:
>
> https://geodata.nationaalgeoregister.nl/bestuurlijkegrenzen/ows?SERVICE=WMS
> (layer 'gemeenten', EPSG:28992)
> And look in F12/debugging window the number of GetMap requests fired when zoomed in...
>
> I copied/created polgyons of the requests, and (see screenie) indeed looking at the center 'tile', the 8 surrounding requests are also fired....
>
> Currently looking into this.
>
> Regards,
>
> Richard Duivenvoorde
>
>
>
>
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