In the Undertow programming model, client requests are handled by listeners and handlers:
Undertow processing
The listener receives the connection and converts the client request into an HttpServerExchange object. This object is sent to the root handler that can delegate execution to another handler or return it.
The return can be done in three different ways: with a 500 error code, a normal return by ending the exchange, or a return without ending the exchange; in the last case, the exchange will be ended. The concrete business logic is provided by handlers; in the next section we will explore Undertow handlers ...
