[mapserver-users] mapcache - is it possible to access different wms sources based on the current resolution or scale?

[Eichner, Andreas - SID-NLKM]

Hi Mark,

> The two layers are in the same grid.  I didn't see any 
> documentation on using symlink for zoom levels.  How would I 
> set that up in my configuration file?

you configure mapcache as usual and symlink the levels for the shared
zoom levels. MapCache creates a directory structure in the filesystem
for every tileset like
<base>/<tileset>/<grid>/<zoom_level>.

You can also create it by hand (watch for correct access rights) and
then symlink directories from the second tileset to the first. It should
look something like this:

# cd <base>/<tileset1>/<grid>/; ls -ld
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 00
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 01
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 02
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 03
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 04
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 05
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 06
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 07
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 08
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 09
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 10
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 11
drwxrwxr-x 2 apache apache 3896 May 14 15:08 blanks

# cd <base>/<tileset2>/<grid>/; ls -ld
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 00
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 01
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 02
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 03
drwxrwxr-x 3 apache apache 3896 Aug 30  2011 04
lrwxrwxrwx 1 root   root     22 Dec  7  2011 05 -> ../../<tileset1>/05
lrwxrwxrwx 1 root   root     22 Dec  7  2011 06 -> ../../<tileset1>/06
lrwxrwxrwx 1 root   root     22 Dec  7  2011 07 -> ../../<tileset1>/07
lrwxrwxrwx 1 root   root     22 Dec  7  2011 08 -> ../../<tileset1>/08
lrwxrwxrwx 1 root   root     22 Dec  7  2011 09 -> ../../<tileset1>/09
lrwxrwxrwx 1 root   root     22 Dec  7  2011 10 -> ../../<tileset1>/10
lrwxrwxrwx 1 root   root     22 Dec  7  2011 11 -> ../../<tileset1>/11
lrwxrwxrwx 1 root   root     22 Dec  7  2011 blanks ->
../../<tileset1>/blanks
drwxrwxr-x 2 apache apache 3896 May 14 15:08
<base>/<tileset1>/<grid>/blanks

This construct shares levels 5-11 between tileset1 and tileset2.