Great explanations, thank you very much.
Indeed, the bavarian authorities seem not to be the leading ones when it
comes to digital data.
Saxony provides nearly everything without limitations via wfs, while in
Bavaria, you still have to pay phantastillions for most of the useful data.
Well, now after wasting hours on this crap, I receive my stupid station
points for major streets for free. Wow!
Cheers,
Bernd
On 07.09.20 11:22, Richard Duivenvoorde wrote:
On 9/7/20 11:02 AM, Richard Duivenvoorde wrote:
'Paging' is in WFS since 2.0. It means that for larger datasets, the service
makes is it possible to request features (in a bbox) based on a COUNT-parameter
and a START(?)-parameter.
So when in a box there are 60000 features, and the service allowes only to
request 10000 feature at a time, you can do that by request six 'pages':
start=0&count=10000
start=10000&count=10000
start=20000&count=10000
etcetc
This off course makes logic both on client AND serverside more difficult: what
if the users zooms out, so part of the features are already loaded in
QGIS/client etc etc...
Serverside this means that you need to have your features ordered and sorted on
a primary key, otherwise you cannot service the 'next' 10000 etc etc
If you look for 'Response paging' in the WFS 2.0 spec docs [0], you see that:
"Response paging is the ability of a client to scroll through a set of response
features or values, N features or
values at-a-time much like one scrolls through the response from a search
engine one page at a time.
Servers that support response paging shall advertise this fact in their
capabilities document using the
ImplementsResultPaging constraint (see Table 13)."
If you look into the capabilties do of your service, you see:
ImplementsResultPaging = FALSE
So it is a little silly to setup a service of such a big dataset without paging
I think? Although it can be usefull if you only request very small parts (at a
time) of course
If you want to see 'paging' at work, you can test this service
https://geodata.nationaalgeoregister.nl/bag/wfs/v1_1?SERVICE=WFS&request=Getcapabilities
(on a small part of The Netherlands, this service holds ALL house in NL)
If you load that service in QGIS you get blocks of 1000 houses back in QGIS,
and in the networklogger you see:
COUNT=1000 (this number comes from a maxcount number in the capabilities) and
STARTINDEX=xxx (so it is 'startindex' and not 'start' as I stated earlier...).
Regards,
Richard
[0] https://www.ogc.org/standards/wfs#downloads
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