Server-side Code
Everything that happens within your server computer is referred to as
server-side processing. When your application needs to interact
with your server (for example, to load or save data), it makes a
client-side request (from the browser) across the network using a
remote procedure call (RPC).
While processing an RPC, your server is executing server-side code.
Tip
GWT doesn't meddle with your ability to run Java bytecode on your
server whatsoever. Server-side code doesn't need to be translatable,
so you're free to use any Java library you find useful.
