In struts 2, Namespace is a new concept to handle the multiple modules by given a namespace to each module. In addition, it can used to avoid conflicts between same action names located at different modules.
Prevent Double click form submission :
Struts2 has a built in mechanism for stopping double form submission that works on the server side instead of the client.
You may need to add the TokenInterceptor if its not on the defaultStack you’re using.