If I already have existing java
web application that uses spring
and servlet
container. What is the proper way to integrate Akka in it? >
I have come across a similar problem.
I agree that there is little benefit of adding AKKA to simple web appliaciton with a small number of users.
But I don't think that it is hard to attach AKKA to existing spring mvc app. In case your project needs to scale you can wrap your @Service layer into actors. Hence, @Controllers do not need to be inside actors.
Here is a presentation on merging spring with akka: https://www.youtube.com/watch?v=fALUf9BmqYE
Source code for the presentation: https://github.com/jsuereth/spring-akka-sample/tree/master/src/main/java/org/springframework/samples/travel