[OpenLayers-Dev] Dynamic SLD in a GetMap-Request via HTTP-POST

Tim Schaub tschaub at opengeo.org
Thu Apr 30 14:20:46 EDT 2009


Andreas Hocevar wrote:
> Hi Ingo,
> Ingo Weinzierl wrote:
>> I am thinking about a topic of my thesis in the next month. While working on a 
>> project using OpenLayers, I asked myself if it's possible to send a WMS 
>> GetMap-Request via HTTP-POST to include a SLD.
>> I have searched for this problem via google, the mailing-lists and in the 
>> examples of OL, but the only way to use SLDs in a GetMap-Request I could find 
>> is via url to a file or in a HTTP-GET url, which has limited length.
>> The idea of my tutor and me is to realize a WMS GetMap-Request via HTTP-POST 
>> to be able to include longer SLDs.
>> What are you thinking about this idea? Or is it absolutely impossible?
> It is actually a good idea, and I would already have developed
> OpenLayers support for it if there weren't other things of higher
> priority. Sending WMS requests via POST is covered by the WMS spec, but
> things become complicated when you want to display the resulting image
> in a browser. Tim Schaub and I have played around a bit with
> XMLHttpRequest and responseStream [1], but it did not work as described
> there. Maybe we were just missing something obvious.

Yeah, my (quick) assumption was that responseStream was not available in 
FF3 (at least).

 >>> var req = new XMLHttpRequest()
 >>> req.open("GET", ".", false);
 >>> req.send(null)
GET http://localhost/    200 OK    15ms
 >>> typeof req.responseStream

So, despite being a "perfectly reasonable way" [1] to request images, I 
haven't seen it work.  Happy to be shown otherwise.



> Having said that: if you want to develop this for OpenLayers, I'll be
> willing to mentor.
> Regards,
> Andreas.
> [1]
> http://code.google.com/support/bin/answer.py?answer=79663&topic=11366#scenario1
>> Regards,
>> Ingo
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Tim Schaub
OpenGeo - http://opengeo.org
Expert service straight from the developers.

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