Akka Streams have four primary stages: Source, Flow, Sink, and RunnableGraph. The lifecycle begins with the creation of a Source, which produces data elements. Flows transform or process these elements, while Sinks consume them. Combining a Source, Flow(s), and Sink creates a RunnableGraph, representing the entire stream processing pipeline.
Stages communicate using asynchronous message-passing via backpressure signals. Backpressure ensures that faster upstream producers don’t overwhelm slower downstream consumers by regulating the rate of data flow between stages. This is achieved through the Reactive Streams protocol, where each stage can signal demand for more data or indicate its current capacity to handle incoming elements.
To connect stages, use methods like ‘via’ (connecting Source to Flow) and ‘to’ (connecting Flow to Sink).
For example :
val source = Source(1 to 10)
val flow = Flow[Int].map(_ * 2)
val sink = Sink.foreach(println)
val runnableGraph = source.via(flow).to(sink)
runnableGraph.run()?
This code snippet demonstrates connecting a Source, Flow, and Sink to create a RunnableGraph, which doubles and prints integers from 1 to 10.
