Re: [thredds] Cache-Control in ncWMS/Thredds

• To: "Heiko Klein" <Heiko.Klein@xxxxxx>, <thredds@xxxxxxxxxxxxxxxx>
• Subject: Re: [thredds] Cache-Control in ncWMS/Thredds
• From: "Jonathan Blower" <j.d.blower@xxxxxxxxxxxxx>
• Date: Wed, 17 Feb 2010 11:17:23 -0000

Hi Heiko,

Cache control is tricky as there is always a danger that cached images
can hang around while the backing data changes.  Hence THREDDS is very
conservative.  ncWMS has more sophisticated caching than THREDDS, for
various technical reasons, but this is implemented at the server side,
rather than using http expiration controls.

It might be possible to have a configuration parameter that enables the
sysadmin to set the expiration time for images from a particular server
(or maybe a particular dataset).  Would this be useful?  Even a figure
of 1 or 5 minutes would help a browser to cache in the case of panning
around a figure.

Cheers, Jon

-----Original Message-----
From: Heiko Klein [mailto:Heiko.Klein@xxxxxx] 
Sent: 15 February 2010 16:33
To: thredds@xxxxxxxxxxxxxxxx
Cc: Jonathan Blower
Subject: Cache-Control in ncWMS/Thredds

Hi,

while trying to get the ncWMS/Thredds operational, I recognized that all
elements (png/getCapabilities) are returned with an expiration date =
Expires Thu Jan 01 1970 01:00:00 GMT+0100 (CET)

This generates a high load on our server, since the browser refetches
each tile while looking around the figure. Is it possible to control the
browser-cache for ncWMS/Thredds?

Best regards,

Heiko

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  • [thredds] Cache-Control in ncWMS/Thredds
    • From: Heiko Klein