In Akka Streams, what are Materializer and RunnableGraph? Explain the relationship between them and their functions.
In Akka Streams, Materializer is responsible for allocating resources and executing the stream’s blueprint, while RunnableGraph represents a reusable blueprint of a stream that can be materialized multiple times. The relationship between them is that a RunnableGraph requires a Materializer to execute its logic.
Materializers allocate necessary resources like actors or threads and handle the actual execution of the graph. They are configurable, allowing users to control aspects such as dispatcher settings and buffer sizes. Commonly used materializers include ActorMaterializer and SystemMaterializer.
RunnableGraphs are created by connecting sources, flows, and sinks using the GraphDSL. They encapsulate the entire stream topology and can be run multiple times with different materializers or configurations. This reusability allows for testing, benchmarking, and modularization of complex stream setups.
To summarize, Materializer executes the stream’s blueprint provided by RunnableGraph, which in turn defines the structure and processing logic of the stream.
