[Tilecache] Cache invalidation

[Yves Moisan]

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 ?

TIA,

Yves