In this chapter, we have first studied how to deal with asynchronous Scala code using the Async toolkit, which simplifies writing nonblocking code using Futures and Promises. We then moved to the concurrency topic by introducing the Akka framework based on the actor paradigm.

Concurrent and distributed systems is such a large topic that we have only introduced some basic usage scenarios of actor systems. We have learned that since the behavior and state of actors are encapsulated, actor systems are easy to reason about. Moreover, the supervision and clustering support in Akka makes the handling of failure and distribution very robust. The material covered in this chapter is just a glimpse of what the toolkit can achieve; the very extended and well-written documentation of the Akka project will guide you through creating scalable and distributed applications. Programming asynchronous, concurrent, and distributed systems is often a complex task, and the actor model makes it more manageable.

Since Akka is also the foundation of the Play Framework, we will continue to use it through the next chapter. We will build reactive web applications in Play to illustrate how to create modern applications that need to handle streams of data and push information into the browser.