C++
The easiest way to access the camera is via XML-RPC. There are many different XML-RPC implementations listed on http://www.xmlrpc.org/.
For example, if you use xmlrpc-c (http://xmlrpc-c.sourceforge.net/), use the included xml-rpc-api2cpp tool to generate a class that can be used to access the camera:
xml-rpc-api2cpp http://camera_address/cgi-bin/rpc le Camera
This will create Camera.h and Camera.cpp, implementing a class called Camera that contains the methods listed in the API.