[OpenLayers-Users] WMS requests executed twice

[Jan Hartmann]

No, "OpenLayers.IMAGE_RELOAD_ATTEMPTS = 0" didn't make any difference ( 
it is the default, anyway). Even so, things are much better than with 
OpenLayers 2.11: I only see a double request for some maps at some 
scales, but I find it difficult to pinpoint what happens. If you have 
any suggestions how to debug this, I'll try to look at it in detail: 
it's important for me to get this proxy-setup right. It could be a proxy 
problem, although I doubt it.

Jan

On 02/08/2012 04:33 PM, Andreas Hocevar wrote:
> Hi,
>
> if what you suspect is true, then the only explanation I have is that
> you have OpenLayers.IMAGE_RELOAD_ATTEMPTS set to something else than
> 0. If you set it to 0, no request should be sent twice. So you could
> check that.
>
> Andreas.
>
> On Wed, Feb 8, 2012 at 3:29 PM, Jan Hartmann<j.l.h.hartmann at uva.nl>  wrote:
>> No, I was too fast: the problem still shows up sometimes, even with the
>> development version of OpenLayers. It looks like OpenLayers does a second
>> request when the webserver takes a long time to return a single-tiled map.
>> For example, I see a single request when requesting a WMS service on the
>> same server within a private network, and two requests when the request
>> comes from the outside and has to pass several proxies to get to the
>> webserver. Also, low-resolution images are served once, high-resolution ones
>> sometimes twice. It is a bit unpredictable, but could that be he problem?
>>
>> Jan
>>
>> On 02/06/2012 06:19 PM, Andreas Hocevar wrote:
>>
>> Hi,
>>
>> this was a big change
>> (https://github.com/openlayers/openlayers/commit/23c909220159134d270064bc4c89440c59c22d20)
>> which fixed a lot of things. In your case in particular, we now don't
>> create a new IMG element for the backbuffer, but keep the existing
>> image, and instead we create a new IMG element for the next tile (i.e.
>> the new extent for single tile layers). For tiles without a cache
>> header (which might get stripped by a proxy), the old behavior meant
>> that the tile is re-requested for the backbuffer.
>>
>> Andreas.
>>
>> On Mon, Feb 6, 2012 at 12:21 PM, Jan Hartmann<j.l.h.hartmann at uva.nl>  wrote:
>>
>> Yes, it *was* that issue: with the development version of OpenLayers layers
>> are always retrieved just once. Thanks Andreas. Just curiosity, can you give
>> me a pointer to what the problem was?
>>
>> BTW, I don't get all messages from the OpenLayers Users list in my mailbox.
>> Had to look up your answers in the archive.
>>
>> Jan
>>
>> ---------------------------------------------------------------------------------------
>>
>> Andreas Hocevar wrote on Mon, 6 Feb 2012 04:01:51 EST 2012
>>
>> Hi, just to clarify, the issue you are seeing (if it's the issue I think it
>> is) was fixed *after* 2.11. Andreas.
>> ----------------------------------------------------------------------------------------------
>>
>> Hi Andreas,
>>
>> No, I use OpenLayers 2.11. I see now that it has something to do with my
>> proxy. All maps are on webservers in an internal network and are accessed
>> via one proxy.When I run the page on the local server, maps are retrieved
>> only once. When I access that same server from the outside, via the proxy,
>> all maps are retrieved twice.
>>
>> Although this is probably not an OpenLayers problem, I would be gratefule
>> for suggestions. It took me quite some time to get the proxy configuration
>> running. It works now, but takes twice as much time as needed.
>>
>> Jan
>>
>> --------------------------------------------------------------------------------------------------------------
>>
>> Andreas Hocevar wrote on Mon, 23 Jan 2012 04:58:20 -0800: This might be due
>> to a bug that has been fixed quite some time ago already. Which version of
>> OpenLayers are you using? Andreas.
>> On 01/21/2012 09:27 PM, Jan Hartmann wrote:
>>
>> Hi all,
>>
>> I made a very simple OpenLayers test site, displaying a simple local
>> MapServer map as an untiled WMS service. Works fine, but when I look in the
>> server log, each OpenLayer GetMap request results in *two* identical
>> requests to the server. Can anyone confirm this, and why does it happen?
>>
>> Jan Hartmann
>> Amsterdam
>>
>>
>> _______________________________________________
>> Users mailing list
>> Users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>
>>
>> _______________________________________________
>> Users mailing list
>> Users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>
>>
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/openlayers-users/attachments/20120208/fb2a638b/attachment-0001.html