[OpenLayers-Users] parallel loading of tiles from same url

[Christopher Schmidt]

On Wed, Apr 09, 2008 at 12:04:42PM +0200, Stefan Zweig wrote:
> hi list,
> 
> i have the following problem:
> 
> i want to use the openlayers to display 2 wms layers, one as a
> baselayer and another one as a (semitransparent) overlay. during
> testing i noticed that, if i use different wms urls to load the wms
> images there is no problem with parallel loading of the tiles. but if
> both wms layers come from the same wms url the api begins to load
> *all* tiles of the baselayer and only after it has finished with
> loading all of them it starts loading the tiles for the overlay, which
> makes loading the map slower.

You know what the doctor says:
 
  If it hurts when you do that, don't do it!

The solution you had -- of loading from a different URL -- is the
recommended way to solve this problem. The only thing that matters is
the domain name: You can set up multiple DNS aliases pointing to the
same system to achieve the speed up. (Like tile.example.com,
overlay.example.com.)

In this way, you can use the same server, but load things in parallel.

I highly recommend this over trying to change the code: switching back
and forth between layers in an effort to load tiles would seriously
complicate things and make your life more difficult, and it would be
somewhat unlikely that we would integrate such a change into OpenLayers
unless it was really nicely done. 

Regards,
-- 
Christopher Schmidt
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