Google maps w/ satellite imagery

[David Bitner]

I have been succesfully using the AJAX concept with Mapserver for a
couple months.  The main thing that I utilize is never refreshing the
whole page.  I parse as much as possible using (extents, which layers
are visible, etc) with Javascript and then change my map image using
mapserver in cgi mode by constructing the url for the image with js.
I also enable XMLHTTP requests to various other utilities such as a
php geocoder that then returns information to the client that can be
used to request a new image as well as display information about the
found address on the client.  In addition, I use PHP and Postgis with
XMLHTTP requests to run my queries without the need to refresh the
image.

The approach that I have been using is to load all my layers as
individual maps with transparent backgrounds.  This is very handy
since some of my layers (larger, complicated, Postgis layers) take
much longer to load than other simple layers.  Regardless of what
layers the user has chosen to display, I preload all the maps to the
client and then only display what the user has selected for display.
This does two things for me.  First, it gives near instantaneous
interaction as the very simple layers come up right away with very
little delay.  Second, once all the layers have loaded, as long as you
don't zoom or pan you can get instant results by turning layers on and
off on the client.