Summary

In this chapter, you have learnt how Java 9 implements the reactive streams specification. It defines a standard for asynchronous stream processing with non-blocking back pressure. It's based on the following three elements:

• A publisher of information
• One or more subscribers of that information
• A subscription between the publisher and a consumer

Java provides three interfaces to implement those elements:

• The Flow.Publisher interface, to implement the publishers of information
• The Flow.Subscriber interface, to implement the subscribers (consumers) of that information
• The Flow.Subscription interface, to implement the subscription between publishers and subscribers

Java also provides a utility class, the SubmissionPublisher class that implements the Publisher interface and can be used if our application has default behavior.

We have implemented two examples with the two implementation variants you can use with reactive streams in Java. We have implemented an event notification system implementing...