read/write XML file on server

Hi all. I have a couple web-based power relays on my network controlling various devices. I want to create a small push button control panel to operate them using momentary buttons with built in LEDs to indicate the status. The setup will likely be an Uno or similar with an ethernet shield.

The web relays use an XML file that provides status information. They're controlled by entering a specific URL into a browser.

Is there any documentation for programming an arduino to read an XML file over a network and in turn submitting commands over the network (in this case a URL)?

I believe it to be a basic "if this then that" type configuration when it comes time to write the code.