[OpenLayers-Users] Re: 'Pragma: no-cache' in OpenLayers WMS getMap request

[Diego Guidi]

I'm not sure to understand your problem, but if you need to avoid
client caching of your requests you can easily manage this stuff using
redraw(true)
http://dev.openlayers.org/docs/files/OpenLayers/Layer/HTTPRequest-js.html#OpenLayers.Layer.HTTPRequest.redraw

as an alternative you can modify the url adding a random string at the
end, somethung like wmsurl&123456.
you can easily manage this task with mergeNewParams
http://dev.openlayers.org/docs/files/OpenLayers/Layer/HTTPRequest-js.html#OpenLayers.Layer.HTTPRequest.mergeNewParams

actually redraw(true) uses mergeNewParams to do it's stuff.

so, you can add a listener to layer.loadstart event and call redraw(true).


Diego Guidi




On Thu, Nov 24, 2011 at 5:10 PM, Jan Henrik Øverland
<janhenrik.overland at gmail.com> wrote:
> And I don't have any meta tags like
> <META HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">
> <META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE">
> in my HTML.
> Jan
>
> On Wed, Nov 23, 2011 at 14:02, Jan Henrik Øverland
> <janhenrik.overland at gmail.com> wrote:
>>
>> Hi,
>> I have WMS overlays (source http://iridl.ldeo.columbia.edu) in my GIS
>> application (built on ExtJS, Mapfish, OpenLayers). It works, but the
>> overlays do not seem to show up any faster after the first load and the
>> Chrome inspector confirms that. So I talked to the guys at columbia.edu and
>> they say that they can se 'Pragma: no-cache' in my getMap requests.
>> My WMS layers are created like this:
>> new OpenLayers.Layer.WMS(
>>     <name>,
>>     <url>,
>>     {
>>         layers: <layers>,
>>         transparent: true,
>>         format: 'image/png'
>>     },
>>     {
>>         isBaseLayer: false,
>>         buffer: 0,
>>         ratio: 1,
>>         singleTile: true
>>     }
>> )
>> How can I control the Pragma parameter? It is obviously not provided in
>> the base url.
>> Jan
>
>
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