xbee and internet

I am working on a project that uses xbee on Arduino to transmit sensor data to our web server via digi connectport X4 gateway.

http://www.digi.com/products/wireless-routers-gateways/routing-gateways/connectportx4

I've read about an open source software - XIG or xbee internet gateway - that can be installed on the gateway to allow xbee to connect to the internet.

http://code.google.com/p/xig/

From online documentation, this software is only able to support HTTP GET if you just print "HTTP://server.address/app?value=123\r". I will get a response but I don't think I can see the HTTP response header.

I would like to do a bit better, establish a TCP connection and send a full HTTP 1.1 request header with POST data and receive the full HTTP 1.1 response header with data. Is it possible or am I asking too much from an xbee module (xbee pro digimesh 900)? Thanks!

There might be some connectport projects that deal with TCP. I'll post something when I find some interesting resources.