[mapserver-dev] Cache-control in WMS Requests

[Paul Ramsey]

Right, that's for Capabilities files, which I'm not touching. I'm just
mucking with GetMap right now, since that's the only API tiled clients
seem to be hitting mapserver with at the moment.

My tests on Safari and Firefox show that the HTTP header really does
make a difference, the browsers hold on to their tiles, so you can
zoom in and out without re-hitting the server for maps you have
already requested.

I'll see if I can figure out how to do the HTTP 1.0 "Expires" header
and then submit a patch.

P.

On 3/18/08, Kralidis,Tom [Burlington] <Tom.Kralidis at ec.gc.ca> wrote:
>
>
>  > -----Original Message-----
>  > From: mapserver-dev-bounces at lists.osgeo.org
>  > [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of
>  > Sean Gillies
>  > Sent: 18 March, 2008 2:01 PM
>  > To: mapserver-dev at lists.osgeo.org
>  > Subject: Re: [mapserver-dev] Cache-control in WMS Requests
>  >
>  > Christopher Schmidt wrote:
>  > > On Tue, Mar 18, 2008 at 10:43:50AM -0700, Paul Ramsey wrote:
>  > >> For reasons of "user ease" having things like this
>  > configured in one
>  > >> place is handy ("how do I improve my Openlayers performance?" "add
>  > >> this one line"). I'm going to test this morning though,
>  > and see how
>  > >> much difference this one header makes to browsers in terms
>  > of actual
>  > >> caching behavior
>  > >
>  > > It should be significant, based on my experience.
>  > >
>  > >> (they might ignore the header because the URL is
>  > "cgi-shaped", etc,
>  > >> etc).
>  > >
>  > > I've never had that problem.
>  > >
>  > >> Unfortunately the rest of the headers that affect caching (last
>  > >> modified, etag, etc) are probably off the table, since
>  > they can't be
>  > >> tracked properly in a dynamic environment.
>  > >
>  > > I'm not sure I agree with this. Perhaps by default you
>  > would want such
>  > > tracking 'off', but certainly one could have a setting
>  > which says "use
>  > > the last modified time of the mapfile for these things",
>  > and use the
>  > > etag/last-modified for that. (Admittedly, it requires more work.)
>  > >
>  > > Regards,
>  >
>  > Doesn't WMS have something "better" than ETag or
>  > Last-Modified? Update sequence?
>  >
>
>
> WMS does, yes.  And MapServer now supports it for all WxS Server
>  support.  See http://trac.osgeo.org/mapserver/ticket/2384 and additional
>  commentary at
>  http://www.kralidis.ca/blog/2008/02/12/mapserver-and-wxs-updatesequence/
>  for more details.
>
>
>  ..Tom
>
>
>
>  > Sean
>  >
>  >
>  >
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