I intend to implement a pure Akka powered REST based Web API. I am not sure about using spray. I would consider using Scalatra if it is any good. Basically I am interested in using the concurrency benefits of Scala Actor model. I don't want the Servlet container to be an hindrance in that process.
What can be other options?
Update 1: Which is better frontend for implementing REST based on Akka backend? - Spray, Scalatra or Dropwizard or any other?
I don't know why you are suspicious of using a Servlet container as the base -- it does not really limit your choice in any possible way, it just handles basic HTTP server plumbing. As such, most java service frameworks use servlet API as the basic foundation even if they don't expose that level.
I think DropWizard is a great choice for all kinds of JVM rest services, including ones that use Akka for actual lifting. Besides the obvious reason of its goodness (based on collection of libraries proven to be "JVM's best"), I like it because it helps in areas that many other libs/frameworks leave out: production of metrics, declarative validation; all the while keeping things simple, explicit and understandable.
