[Tilecache] Cache invalidation

[Christopher Schmidt]

On Fri, Mar 27, 2009 at 09:37:00AM -0400, Yves Moisan wrote:
> Hi All,
> 
> Say I'm using a WMS layer that I would otherwise use as a vector layer
> if browsers could support 1000's of features and remain on their feet
> e.g. when zoomed out the layer is shown as WMS and as one zooms in the
> layer is served in a vector format when the number of features becomes
> beareable.  When zoomed out, I could query via GetFeatureInfo and when
> zoomed in I could do a GetFeature.
> 
> We were thinking of tilecaching the WMS and redirect the GetFeatureInfo
> call on the tilecached layer (the only one visible to the user) to the
> WMS service that tilecache calls to render the images.  Now, my
> "feature-served-as-WMS" layer will change over time since applications
> are writing in the database and so the question is : can TileCache
> invalidate a cached image and call the WMS server to regenerate a tile ?
> I guess that one could trigger a tilecache_seed on a particular tile or
> set of tiles upon a database CRUD operation, but is there a cache
> invalidation scheme in TC ?

There is support for "DELETE" on a tile, which causes it to be
invalidatd (and all tiles below it as well). Thre is no support for
automatic cache expiration/invalidation.

> TIA,
> 
> Yves  
> 
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-- 
Christopher Schmidt
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