[OSGeo-Discuss] The state of WMS tile caching

Christopher Schmidt crschmidt at crschmidt.net
Wed Nov 26 04:45:00 PST 2008

On Wed, Nov 26, 2008 at 07:37:54AM -0500, Christopher Schmidt wrote:
> On Wed, Nov 26, 2008 at 12:46:48PM +0100, Gilles Bassière wrote:
> > I was recently confronted to the same problem. I needed a cached WMS, 
> > although on some occasion I would need to perform untiled map requests. 
> > Of course, it would have been much easier to send tiled and untiled 
> > request to a single front server.
> > 
> > My idea was to hack TileCache. Indeed, TileCache already has WMS request 
> > support et grid calculation and cache and so on. When the requested 
> > extent/size does not match the tile grid, TileCache returns an error. I 
> > guess it would be possible to catch this error. Then, instead of 
> > returning the error to the client, it should be possible to forward the 
> > request to the rendering back-end and return the resulting image to the 
> > client (without storing it in the cache). I'm not sure whether this 
> > could be possible with all back-end. 
> At this time, yes, in the future, no. 

I should qualify/explain this: one of my short term goals is to allow
for requesting tiles in TileCache from a backend TMS service (making
TIleCache a proxy, of sorts), which would mean that you could only
request along the pre-built grid. 

Christopher Schmidt
Web Developer

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