[Featureserver] Featureserver caching

[Christopher Schmidt]

On Mon, Oct 08, 2007 at 06:42:02PM +0100, david creane wrote:
> >>crschmidt=# create table osi.roads (id int);
> >>ERROR:  schema "osi" does not exist
> 
> >>I don't know how I'd create a table like that. Do you have an 'osi'
> >>schema or something?
> 
> Yes, sry, it is a schema, forget what i had said, im only figuring out 
> postgres as i go along, using a database set up by someone else. I set the 
> search_path to include osi. 
> 
> Just a few questions.
> When calling a wms layer say at zoom level 1 , tilecache make 6 calls to 
> server say for example passing different  sets of numbers ranging from the 
> bounding box of 4885,-62828,381091,501480
> 
> why is the feature server using a greater bounding box then the one i define 
> in the layer options. I know the tilebounds is calculated in 
> openlayers/lib/OpenLayers/Layer/WFS.js but im not sure as to why it is done 
> like this.

WFS Layers are not tiled. Since features may overlap between two
different bounding boxes, this would result in the same feature data
being loaded twice, so we made that not the case.

In order to not need to load a new feature every time the map is
dragged, we select a bounding box that is layer.ratio times the size of
the current map extent, which means it will be larger than the map extent
at times.

Regards,
-- 
Christopher Schmidt
MetaCarta