[mapserver-dev] testing CLUSTER object

[Jeff McKenna]

Hello Tamas,

Although there is a workaround, my personal opinion is that 6.0 
shouldn't go out the door until we allow querying of the cluster object. 
  It is only my opinion, as I can see myself having to answer these 
questions on the mailing list over and over again, so I am trying to 
avoid it.  Maybe Stefanie can respond to this mailing list also?

-jeff



-- 
Jeff McKenna
MapServer Consulting and Training Services
http://www.gatewaygeomatics.com/




On 11-05-05 10:11 AM, Tamas Szekeres wrote:
>
> 2011/5/5 Jeff McKenna <jmckenna at gatewaygeomatics.com
> <mailto:jmckenna at gatewaygeomatics.com>>
>
>
>     Hmm, yes I think this is related to a point I made to the
>     mapserver-dev list when I initially tested the cluster object (see
>     below).  I could only ever receive one result when querying a
>     cluster object (I assumed all features inside the cluster object
>     would be returned by a query). Hopefully this generates some
>     discussion on the mapserver-dev list.
>
>
> Hi Jeff,
>
> The term "all features inside the cluster object would be returned by a
> query" would imply that the cluster provider should behave differently
> according to the query and the drawing operations. Currently there's no
> reliable mechanism to identify a purpose of a particular feature access
> so this cannot be implemented in this form. We have been talking about
> (with Steve) to use the query object of the map for this purpose,
> however it is not handled consistently throughout MapServer (for example
> in drawQuery) so it cannot be utilized here.
>
> What I have already mentioned to workaround the problem, is to use an
> union layer (with cluster setting) to provide the drawing and use the
> source layer(s) to provide the query results, something like:
>
> LAYER  # non queryable, might not be exposed in WMS
>      NAME "cluster-layer"
>      CONNECTIONTYPE UNION
>      CONNECTION "source-layer"
>      STATUS default
>      CLUSTER
>          REGION "ellipse"
>          MAXDISTANCE 40
>      END
>      CLASS
>          ....
>      END
> END
>
> LAYER
>      NAME "source-layer"
>      TEMPLATE "query"  #queryable
>      CONNECTIONTYPE OGR
>      CONNECTION ...
>      STATUS default
>      CLASS
>          STATUS off  # do not draw this layer but expose in legend
>          ...
>      END
> END
>
>
> Best regards,
>
> Tamas
>
>