Hi Arne
The reason is that we collect WMS from different providers. The idea with caching is, that we have a “copy” of the data in our cache - und can serve our system with this, when one of the “source WMS” of which we haven’t any control, isn’t working.
I’m not sure if this is really possible?
The other idea was to collect “all tiles” of the “source WMS”, save them as png locally and use them this way. I think this is quite exactly what geowebcache is doing.
If I’m completely wrong - I’m happy for any advice.
Thank you.
Christian
I’ve read the followups, but it is stilll unclear to me why you are invoking GWC at all ?
GWC stores many small tiles in PNG or JPEG format. It is rather expensive to decode these tiles and to combine them into a new image.
Last time I checked it was a lot slower than using an optimized GeoTIFF as the source, and I think (but I haven’t checked) you need a pretty hefty dataset + styles for this to be slower than rendering vector straight from the database.
So why not just use WMS ? The ability to combine tiles was written for a very extreme case, a legacy WMS backend that was unbearably slow and couldn’t be fixed.
-Arne
–
Christian Höhener
Demutstrasse 21
9000 St.Gallen
Tel. 071 534 80 04
Mobile. 079 417 38 53
Yeah, the case you describe is very similar to the one for which this feature was written. And now I do see you said it in one of the follow ups I obviously missed, sorry.
That is the only way forward that I can think of. And tell all of the providers to switch to clusters of GeoServers for increased reliability and decreased costs 
-Arne
On 9/14/12 06:52 , Christian Höhener wrote:
Hi Arne
The reason is that we collect WMS from different providers. The idea with caching is, that we have a "copy" of the data in our cache - und can serve our system with this, when one of the "source WMS" of which we haven't any control, isn't working.
I'm not sure if this is really possible?
The other idea was to collect "all tiles" of the "source WMS", save them as png locally and use them this way. I think this is quite exactly what geowebcache is doing.
If I'm completely wrong - I'm happy for any advice.
Thank you.
Christian
---------
I've read the followups, but it is stilll unclear to me why you are invoking GWC at all ?
GWC stores many small tiles in PNG or JPEG format. It is rather expensive to decode these tiles and to combine them into a new image.
Last time I checked it was a lot slower than using an optimized GeoTIFF as the source, and I think (but I haven't checked) you need a pretty hefty dataset + styles for this to be slower than rendering vector straight from the database.
So why not just use WMS ?The ability to combine tiles was written for a very extreme case, a legacy WMS backend that was unbearably slow and couldn't be fixed.
-Arne
--
--------------------------------
Christian Höhener
Demutstrasse 21
9000 St.Gallen
Tel. 071 534 80 04
Mobile. 079 417 38 53
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