adding another data source to mapserver (PostGIS)

[Dave Blasby]

I am trying to add a new datatype to mapserver.  I've looked at the
maplayer.c file, and it seems I just have to add support for the
functions referenced within.

Could anyone give me a discription of what these functions are supposed
to do, and when they are called?  I'm sure I'm going to miss something
subtle if I just try to follow the examples.


The mapfile documentation seems to indicate that CLASS objects can only
contain 'logical expressions' when used with shapefile.  Is this true? 
How could I have my data type also support this?

The data type I'm trying to add is PostGIS.  PostGIS adds support for
real geographic objects to the PostgreSQL object-relational database. In
effect, PostGIS "spatially enables" the PostgreSQL server, allowing it
to be used as a backend spatial database for geographic information
systems (GIS), much like ESRI's SDE or Oracle's Spatial extension.

PostGIS is distributed under the GPL.

We are excited to be adding web mapping support to PostGIS using
mapserver.

thanks,
dave