GWT: How to send one variable from client side code to server side code

Thanks for helping me,i can not explain everything but simply I am writing as follows

Say,inside the client file (which implements EntryPoint), a variable DELAY=200,has its initial value but after some time client needs to send this value to the server side code where in server开发者_如何转开发 side (DataServiceImpl.Java) file the initial value was sDelay=500, then it will be changed to 500 to 200(client variable). How to do this ??How to pass these values ?

Thanks for your time.

Google Web toolkit

The GWT developer guide contains an entry on client-server communication. There are also a fair number of third-party libraries that offer a variety of feature-sets.