Re: [thredds] ncWMS GetCapabilities return sometimes empty document

• To: Ethan Davis <edavis@xxxxxxxxxxxxxxxx>
• Subject: Re: [thredds] ncWMS GetCapabilities return sometimes empty document
• From: Heiko Klein <Heiko.Klein@xxxxxx>
• Date: Thu, 18 Feb 2010 12:37:05 +0100

Hi Ethan,

I have investigated a bit more on the problems with ncWMS/thredds. On a
freshly restarted server, I don't see any problems as long as I don't
use our openlayers-based WMS client. I even put a high load on the
machine, reading both getCapabilities and getMap.


The difference between the command-line and openlayer-client is, that
the openlayer-client has to read the getCapabilities document through a
web-proxy, which is on the same machine as the client-web-page. This is
allways the case where a javascript client has to read the
getCapabilities document, since javascript security forbids to read data
from a different domain.

As long as a request is stateless, reading through a proxy is no
problem, but the GetCapabilities response is strange since it sets a new
JSESSIONID:

Request-Header:
GET
/thredds/wms/osisaf/met.no/ice/ice_conc_nh_200911291200_CF.nc?service=WMS&version=1.3.0&request=GetCapabilities
HTTP/1.1
Host: dev-vm188
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2)
Gecko/20100115 Firefox/3.6
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,nb;q=0.8,no;q=0.5,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Cookie: JSESSIONID=5FC30B2901A7D5DADDCF1A6E171BB318

Response-Header:
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=FC5891CC7B9BE38017750523E0CAEE83; Path=/thredds
Cache-Control: no-cache
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Content-Type: text/xml
Content-Language: de-DE
Transfer-Encoding: chunked
Content-Encoding: gzip
Vary: Accept-Encoding
Date: Thu, 18 Feb 2010 10:25:08 GMT


Why does ncWMS start a new session, ignoring the old one? And in my case
with the proxy, the cookie will be set against the proxy, not the
thredds, so all further requests to thredds will use the old, outdated
Cookie.


I don't know if this is actually the reason, it is just an idea yet. Is
it simple to disable session for the whole ncWMS part?

Best regards,

Heiko

• Follow-Ups:
  • Re: [thredds] ncWMS GetCapabilities return sometimes empty document
    • From: Heiko Klein

• References:
  • [thredds] ncWMS GetCapabilities return sometimes empty document
    • From: Heiko Klein
  • Re: [thredds] ncWMS GetCapabilities return sometimes empty document
    • From: Ethan Davis
  • Re: [thredds] ncWMS GetCapabilities return sometimes empty document
    • From: Heiko Klein