From the Spray Website:
Spray is a suite of lightweight Scala libraries providing client- and
server-side REST/HTTP support on top Akka.Fully asynchronous, non-blocking
All APIs are fully asynchronous, blocking code is avoided wherever at all
possible.Actor- and Future-based
spray fully embraces the programming model of the platform it is built upon.
Akka Actors and Futures are key constructs of its APIs.High-performance
Especially sprays low-level components are carefully crafted for excellent
performance in high-load environments.Lightweight
All dependencies are very carefully managed, sprays codebase itself is kept
as lean as possible.Modular
Being structured into a set of integrated but loosely coupled components your
application only needs to depend onto the parts that are actually used.Testable
All spray components are structured in a way that allows for easy and
convenient testing.