Communicating with a server

At some point, most GWT applications will need to interact with a backend server. GWT provides a couple of different ways to communicate with a server via HTTP. You can use the GWT RPC framework to transparently make calls to Java servlets and let GWT take care of low-level details like object serialization. Alternatively, you can use GWT's HTTP client classes to build and send custom HTTP requests.

Specifics

GWT RPC An easy-to-use RPC mechanism for passing Java objects to and from a server over standard HTTP.

HTTP Calls For more fine-grained control, make custom HTTP requests and optionally process the responses using GWT's JSON and XML client classes.