[OpenLayers-Users] Overlay dont "refresh" with setcenter forcezoom.

[Tom (JDi Solutions)]

Another idea, if it is indeed browser caching, you could try putting another
arg on the end of the wms requests to make them different, say a counter for
example.  Geoserver will ignore it but it will ensure the URLs are always
different and may stop the browser caching it.

On 8/26/07, Tom (JDi Solutions) <tom.dean at jdi-solutions.co.uk> wrote:
>
> Not sure what to actually do about it but could it be that the tiles are
> being cached by the browser?  In my experience browser caching can be
> unpredictable at best especially when you consider that corporate content
> filters / firewalls and proxies also often have caching features.  There are
> ways to set the headers on files to tell the browser not to cache it but
> they are not reliable.  Maybe OpenLayers / Geoserver has a clever way around
> this?  One way you could possibly improve things is to set your overlay to
> be non tiled, that way the requests will almost always be different and the
> browser won't cache them.
>
> On 8/26/07, Jonke <jonke at bt.nu> wrote:
> >
> >
> > I really like openlayers.
> >
> > However I have problem with the automatic refresh of a overlay (that is
> > a
> > layer that is not a baselayer).
> > I have read thorough all the examples and I especially the one with the
> > Webcam.
> >
> > However I start by describing the setup.
> >
> > I have a baselayer (a big one with many layers in it served by
> > GeoServer)
> > changes very rare.
> >
> > I have a almost realtime dataset with 1 000 000 items, changes very
> > frequently (300 000 changes every 30s), this is setup as a transperent
> > overlay with the isbaselayer: false. ( We can call this layer for
> > overlay)
> >
> > Both the baselayer and overlay have the tiled attribute set (not a
> > tiledcache as a backend but just a vanilla geoserver).
> >
> >
> > When I scroll and pan and use the zoomin zoomout with the Mouse, the
> > overlay
> > is properly refreshed and everything is fine.
> >
> > When I try to do this javascript wise to get a "automatic refresh" (with
> > a
> > map.setCenter or layer.moveTo and the forcezoom to true), then I only
> > see
> > the old overlay that seems to have been cached somewhere (and it is not
> > by
> > the geoserver). I have tried different things, "zoomOut();zoomIn();" and
> >
> > "removelayer(overlay);addlayer(overlay)" with no luck.
> >
> > Could it be that the layers are tiled and as long as I am in the same
> > tile a
> > new request to the geoserver is not spawned?
> >
> > I've read the openlayers source but I can't pinpoint where the decision
> > to
> > retrieve or not retrieve data from the geoserver is done.
> >
> > I tried to remove the tiled attribute for the overlay but that seem to
> > do
> > not what I intended but to download a very large tile of my overlay and
> > still not updateing using center, moveto.
> >
> > But here comes the 'scratch my head' part, if I with firefox open two
> > tabs
> > to the same url where my openlayers are and switch back and fort between
> > them, then the center method works with both layers having the tiled
> > attribute. If I stay in one tab I don't see any change of my overlay, if
> > I
> > go to the next tab the overlay is refreshed and then I go back to the
> > first
> > tab the overlay is refreshed.
> >
> > If someone can point me to the "right way" todo this with many
> > geometries I
> > will gladly test another approach.
> >
> > Regards.
> > --
> > View this message in context: http://www.nabble.com/Overlay-dont-%22refresh%22-with-setcenter-forcezoom.-tf4327410.html#a12324516
> >
> > Sent from the OpenLayers Users mailing list archive at Nabble.com.
> >
> > _______________________________________________
> > Users mailing list
> > Users at openlayers.org
> > http://openlayers.org/mailman/listinfo/users
> >
>
>
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