The major problem in coding is to write scalable concurrent modules. One of the solutions to the problem is provided by Message Passing Paradigm. Akka is a JVM-based toolkit and is written in Scala. It was introduced by Steven Haines, which implements actor-based model. The actors provide abstract and simple, yet powerful high-level concurrency modules. It supports asynchronous, non-blocking, event-driven programming to create application with high performance. Although Akka is altogether a different topic to discuss, which is out of the scope of this book, we will discuss a few things here to get an idea about it.

In OOPs programming, the developers create objects of the classes and invoke the business logic methods directly. Akka is purely based on the asynchronous message passing strategy in a distributed environment. The actor-based model constructs a message, and it is sent to the object. The object to which the message is sent is called actor. Internally, it's an object of the class that implements the Actor interface. The actor now stores the message. On the availability of the thread, the engine running the actor delivers the message to the object where its destiny is set. Once the actor completes the task, it sends the message back to the object that originated the message. This results in less overhead while handling concurrency.