/ˈækə/
noun … “Toolkit for building concurrent, distributed, and resilient systems.”
Akka is a toolkit and runtime for building highly concurrent, distributed, and fault-tolerant applications on the JVM. It implements the Actor Model, allowing developers to create isolated actors that communicate exclusively via asynchronous message passing. By encapsulating state within actors and avoiding shared mutable memory, Akka simplifies Concurrency and enables scalable, responsive systems.
Key characteristics of Akka include:
- Actor-based concurrency: actors process messages sequentially and independently, eliminating the need for explicit locks.
- Fault tolerance: supervisors monitor actors and can restart them on failure, enabling resilient systems.
- Scalability: supports distributed deployments across multiple nodes or CPUs.
- Event-driven and asynchronous: designed for high-throughput and low-latency applications.
- Integration: works with Scala and Java, leveraging existing JVM ecosystems.
Workflow example: In a web service using Akka, each incoming request is assigned to an actor. The actor handles validation, executes computations, and responds asynchronously. Multiple actors run in parallel without shared state, allowing the service to handle thousands of requests concurrently without locks.
import akka.actor._
class Printer extends Actor {
def receive = {
case msg: String => println("Received: " + msg)
}
}
val system = ActorSystem("PrintSystem")
val printer = system.actorOf(Props[Printer], "printer")
printer ! "Hello Akka"Conceptually, Akka is like a city of independent workers (actors), each managing their own tasks and communicating via messages. The city scales efficiently because workers do not interfere with each other, and failures are contained and managed locally.
See Actor Model, Scala, Concurrency, Threading.