[mapserver-users] Mapcache with mapfile as layer

Pablo Cecconi pc at educ.ar
Thu Sep 19 19:24:14 PDT 2013


Well, maybe I'm not getting it right but it seems to me that this file:

https://github.com/mapserver/mapcache/blob/master/lib/source_mapserver.c

and this example in the
https://github.com/mapserver/mapcache/blob/master/mapcache.xml.sample:

  <source name="osm" type="wms">
      <http>
         <url>http://localhost/cgi-bin/mapserv?</url>
      </http>
      <getmap>
         <params>
            <FORMAT>image/png</FORMAT>
            <LAYERS>default</LAYERS>
            <!--<MAP>/Users/tbonfort/dev/mapserver-utils/empty.map</MAP>-->
            <MAP>/Users/tbonfort/dev/mapserver-utils/osm-google.map</MAP>
         </params>
      </getmap>
   </source>

would suggest that, although not documented, mapcache might be able to talk
to mapserver through the cgi protocol if built with the USE_MAPSERVER flag.
I can't wait to test it!



On Thu, Sep 19, 2013 at 11:08 PM, Stephen Woodbridge <
woodbri at swoodbridge.com> wrote:

> Thanks, I would be interested in hearing how you work this out. It might
> help to remember that mapcache ONLY talks to mapserver via the WMS
> protocol, NOT the mapserver CGI protocol. This is a big difference from
> TileCache. Anyway good luck with your efforts.
>
> -Steve
>
>
> On 9/19/2013 10:00 PM, Pablo Cecconi wrote:
>
>> The problem is not the invalidation of the tiles (which is a very simple
>> step that can even be done with a simple bash script) but the need to
>> list every single layer with status ON on the mapfile. To do that
>> automatically we need to use mapscript (as TileCache does) but we also
>> need to deal with generating a valid mapcache config file (which we
>> cannot do with mapscript). With TileCache instead we just mapped a given
>> layer name with a mapfile and we only had to care about invalidating and
>> reseeding of tiles and not with modifying TileCache config file. It's
>> not so bad though. I just thought that being part of Mapserver maybe
>> MapCache could have some kind of "special integration" with it.
>> Anyway, I'll continue digging to see if I find some easier way to deal
>> with this particular problem and if I do I promise to let you know.
>> Thanks again.
>>
>> Pablo
>>
>>
>>
>> On Thu, Sep 19, 2013 at 10:18 PM, Stephen Woodbridge
>> <woodbri at swoodbridge.com <mailto:woodbri at swoodbridge.**com<woodbri at swoodbridge.com>>>
>> wrote:
>>
>>     Try it, it might work, I don't remember, but you still have the
>>     problem of invalidating the tiles when you changes the mapfile. But
>>     seriously, your approach seems a little haphazard. Also how often to
>>     you make mapfile changes? how did you deal with the invalidating
>>     cache problem before?
>>
>>     The big difference here is that mapcache is using mapserver as a WMS
>>     source and therefore it has to conform to the WMS rules.
>>
>>     Anyway, Thomas is the one that you would need to convince or fund if
>>     you want changes to the existing behavior. Meanwhile it would be
>>     worthwhile your time to figure out how it curently works before
>>     asking for features that might already exist. It has been a few
>>     months since I setup a mapcache instance and I know there have been
>>     changes that I'm not on top of in the newest  release.
>>
>>     -Steve
>>
>>
>>     On 9/19/2013 3:46 PM, Pablo Cecconi wrote:
>>
>>         The problem with that approach is that is the mapfile changes (a
>>         layer
>>         is added or the default status of a layer changes) then I also
>>         have to
>>         update mapcache config file. What i wonder is if there is a way
>>         to just
>>         modify the map and have Mapcache reflecting that change.
>>
>>         Pablo
>>
>>
>>         On Thu, Sep 19, 2013 at 4:40 PM, Stephen Woodbridge
>>         <woodbri at swoodbridge.com <mailto:woodbri at swoodbridge.**com<woodbri at swoodbridge.com>
>> >
>>         <mailto:woodbri at swoodbridge.__**com
>>
>>         <mailto:woodbri at swoodbridge.**com <woodbri at swoodbridge.com>>>>
>> wrote:
>>
>>              On 9/19/2013 3:02 PM, Pablo Cecconi wrote:
>>
>>                  Hello,
>>
>>                  I've been a Mapserver user for many years now but I'm
>>         new to
>>                  Mapcache
>>                  and I'm not sure whether it's possible to replicate a
>>         particular
>>                  TileCache setup using Mapcache.
>>                  What we have today is a number of mapfiles (with
>>         Mapserver 5.4)
>>                  set up
>>                  as WMS-C layers served with TileCache. We're migrating
>>         to Mapserver
>>                  6.2.1 and as it's incompatible with TileCache we expect
>>         to be
>>                  able to
>>                  replace it using Mapcache.
>>                  In our current setup if I have a mapfile where a
>> particular
>>                  layer has
>>                  STATUS OFF then TileCache will honor that status and
>>         not render
>>                  the layer.
>>                  I'd like to know whether it's possible to have MapCache
>>         work
>>                  that way,
>>                  that is, passing the map name as the LAYERS parameter
>>         of the WMS
>>                  service
>>                  and make it honor whatever STATUS a particular layer
>>         would have
>>                  in the
>>                  mapfile.
>>
>>
>>              I think the mapcache paradigm for this in mapcache works
>>         like this:
>>
>>              tileset
>>                 name=foo
>>                 source=foo-source
>>
>>              source
>>                 name=foo-source
>>                 map=/path/to/mapfile
>>                 layers=layer1,layer2,layers3,.**____..
>>
>>
>>
>>              So you can configure which layers a tileset returns. I'm
>>         not sure
>>              how it deals with the status off, but it will work if you
>>         define the
>>              list explicitly. This also allow you to do this in the same
>>         mapcache.xml
>>
>>              tileset
>>                 name=foo2
>>                 source=foo-source2
>>
>>              source
>>                 name=foo-source2
>>                 map=/path/to/mapfile
>>                 layers=streets,...
>>                 transparent=true
>>
>>              I do this a lot when I have a subset of data like streets
>>         that I
>>              want to render as an overly on a raster image
>>
>>              -Steve W
>>              ______________________________**_____________________
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>>
>>
>>
>>
>
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