As darkinferno pointed out, there's ANet (there's a http version which focuses on http protocolls which I think is what you need), there's also the free GSTNet http://www.gstools.de/index.php/3dgs-plugins-mainmenu-119/gstnet-mainmenu-121 which comes with http functions.

Also, if you own the right 3dgs version (Pro, I believe), http commands are supported natively.
For the functions you described the best way is to have php scripts sitting on your main server which answer the http requests.