How to implement XSRF in SmartGWT?

I use SmartGWT 4.1p and I have read the javadoc of RPCManager.setActionURL that mentioned SmartGWT support the implementation of XSRF protection.

I want to know
1. how to generate XSRFToken? in client side or server side?
2. how to set the token by setActionURL
3. any setting in server side? do we need to change web.xml and add any servlet if for SmartGWT?
4. any special steps if we want to protect the DMI communication...