[mapserver-users] Image Speed Questions---Generic

[Doyon, Jean-Francois]

That's what he meant, the browser will do the caching for a given URL unless
the HTTP headers indicated otherwise.  By default MapServer pages ARE cached
by the browser, unless you added some custom headers to change that
behavior, which is a fairly standard trick.  This is especially easy if
you're using MapScript/PHP, but can also be done through Apache
configuration.

J.F.

> ----------
> From: 	Ed McNierney[SMTP:ed at topozone.com]
> Sent: 	Tuesday, July 31, 2001 10:50 AM
> To: 	ddnebert at fgdc.gov; Mapserver Users
> Subject: 	RE: [mapserver-users] Image Speed Questions---Generic
> 
> Hmmm.  Since these pages are generated by a CGI program, I'd be
> surprised to find a server caching them.  How does the server know that
> the program isn't querying a database that just got updated?  If my page
> was:
> 
> http://mybank.com/account.cgi?getbalance=345678980
> 
> and it reported my bank account balance, I would expect the server to
> NOT cache the result.
> 
> On the other hand, your BROWSER could very well be doing this.
> Depending on your browser version and brand preference, there are
> various settings that will control whether the browser will re-query the
> Web server for an identical URL.  Your browser may be set up to not
> check again (at least during the current session) if the URL is the
> same.
> 
> 	- Ed
> 
> Ed McNierney
> Chief Mapmaker
> TopoZone.com
> ed at topozone.com
> (978) 251-4242
> 
> 
> -----Original Message-----
> From: Doug Nebert [mailto:ddnebert at fgdc.gov]
> Sent: Tuesday, July 31, 2001 8:20 AM
> To: Mapserver Users
> Subject: Re: [mapserver-users] Image Speed Questions---Generic
> 
> 
> Walt Lin wrote:
> > 
> > On the note of trivial rejection and tileindices, what about this
> solution: store the extents of all the different shapefiles (perhaps one
> per county on a national level) in a postgres table with an R-Tree
> index.  When a request comes in, query Postgres for all the shapefiles
> that intersect and load them using mapserver.  Of course, POSTGIS would
> be optimal, storing everything in Postgres, but from what I've heard
> this is really slow in practice.  Thoughts?
> > 
> > Walt
> 
> Actually a simpler technique is quite feasible: If you request a map
> using the exact same URL (extents, layers, etc) then a caching 
> webserver will provide the map from the cache instead of requesting
> it. I have seen this work quite well on all sizes of datasets. By
> having pre-set extents, such as counties, you can encourage this
> behavior.
> 
> Doug.
> -- 
> Douglas D. Nebert
> Geospatial Data Clearinghouse Coordinator 
> FGDC/GSDI Secretariat	Phone: +1 703 648 4151	Fax: +1 703 648-5755	
> Pager Messaging: 	http://clearinghouse3.fgdc.gov/dougmsg.html
>