Just a sketch for async-REST with Spring.

Run main application (AsyncRestApplication), and open one of the following URL's in browser:

• regular, blocking behaviour

http://localhost:8880/blocking/<SOME_STRING>

• async caller but expensive resource not decoupled - solved with Callable

http://localhost:8880/callable/<SOME_STRING>

• same as above, DeferredResult instead of Callable

http://localhost:8880/deferred/<SOME_STRING>

• fully async. Fakes a real messaging-system (JMS, Kafka,...)

http://localhost:8880/fully-async/<SOME_STRING>