MS RFC 8: Pluggable External Feature Layer Providers

[Daniel Morissette]

Jani Averbach wrote:
> 
> I would like to ask MS TSC to vote for this proposal. I am sorry that this 
> came so late, but if this passes, it will be ready and implemented for coming 4.8
> before feature freeze.
> 

You realize that Oct 31st is only 4 days away?

> The proposal is important because it actually implements the way to include external
> providers for Mapserver.  As technically, it isn't very big because mostly all work 
> has been done by MS-RFC-3 (vtable architecture).
> 
> http://ms.gis.umn.edu/development/rfc/ms-rfc-8
> 

In the proposal you wrote:

> Technical Solution
> 
>     * New MAP-file keyword PLUGINLIB with string argument. This keywords tells which library dynamically to load for this layer.
>     * New connection type CUSTOM
> 

So this means that the PLUGINLIB parameter needs to be set explicitly 
for each layer that uses a given plugin? Is the value the full path to a 
.so file (DLL on Windows)? e.g.
PLUGINLIB  "/opt/mapserver/plugins/myplugin.so"

This could make it painful to migrate mapfiles from windows to Linux 
because then you need to edit every single layer to change the path and 
extension.

How about a more automated mechanism where we set a MS_PLUGIN_DIR 
variable in the environment prior to calling MapServer or via a CONFIG 
directive at the map level, then the PLUGINLIB becomes a PLUGIN keyword 
whose value is the basename of the plugin file?

e.g. the example above becomes:

MAP
   ...
   CONFIG "MS_PLUGIN_DIR" "/opt/mapserver/plugins"
   ...

   LAYER
     CONNECTIONTYPE CUSTOM
     PLUGIN "myplugin"
     ...
    END
END


Daniel
-- 
------------------------------------------------------------
  Daniel Morissette               dmorissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------