Mapserver caching and map generation

[Emmanuel BELO]

Thank you Ed for your answer,

We are working with data supplied from postgis. Images will mainly be 
cached (neither pan neither zoom, only defined shortcuts).

After some test, it occurs that images that are often requested are 
faster delivered that others. Is there an "expire after time" parameter 
for cached images?

eb



Ed McNierney wrote:
> Emmanuel -
> 
> Each map request generates a unique image, and the URL for that image is
> returned to the client browser requesting that image.  Since your Web
> server can process several HTTP requests at one time, there can be
> several MapServer instances all running at the same time.
> 
> There will be some interaction with the disk subsystem on which the
> temporary images are written, and from which they are read by the client
> browsers.  Some disk systems can handle multiple simultaneous read/write
> requests better than others.  Nothing will break - but some disk
> subsystems will take longer than others to respond when multiple reads
> and writes are happening.
> 
> In case you haven't discovered it yet, using MapServer as a WMS server
> or in the CGI "mode=map" mode, the output image is written directly to
> the client and no temporary files are written to disk.
> 
>      - Ed
> 
> Ed McNierney
> President and Chief Mapmaker
> TopoZone.com / Maps a la carte, Inc.
> 73 Princeton Street, Suite 305
> North Chelmsford, MA  01863
> ed at topozone.com
> (978) 251-4242  
> 
> -----Original Message-----
> From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
> Behalf Of Emmanuel BELO
> Sent: Wednesday, March 01, 2006 12:26 PM
> To: MAPSERVER-USERS at LISTS.UMN.EDU
> Subject: [UMN_MAPSERVER-USERS] Mapserver caching and map generation
> 
> Hello,
> 
> after cleaning the cache, mapserver generates the new images on request.
> 
> What happens if 10 users ask for the same map during the generation of
> the first map? Are their request delayed or will 10 processes in
> parallel be initiated?
> 
> Best regards,
> 
> Emmanuel BELO
> emmanuel.belo at microgis.ch
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