I. Technologies

- Java 9 - Eclipse with Java 9 Support for Oxygen (4.7)

II. Overview

1. Processor

A Processor is a component that sits between the Publisher and Subscriber. It acts as: + a Subscriber when emitting a request signal to Publisher + a Publisher when pushing items to Subscriber.

We can create one or more Processors in chain which link a Publisher to a Subscriber.

2. Project

We will create a Publisher that is subscribed by a Processor, and that Processor will publish data to a Subscriber. - Publisher define a Subscription to work with Processor. - Processor define its own Subscription to work with Subscriber.

• Using Subscriber::onNext() method, Publisher pushes items to Processor, and Processor pushes items to Subscriber.

• Using Subscription::request() method, Processor requests items from Publisher, and Subscriber requests items from Processor.

• Publisher and Processor defines an Executor for multi-threading. Then request() and onNext() method work asynchronously.

• Processor has a data buffer to store items in case the demand number of items requested by Subscriber and Processor are different.

III. Practice

To understand how Publisher, Subscriber, Subscription and Processor behave and way to implementing them, please visit: Java 9 Flow API – Reactive Streams

Publisher<Integer> ------ Processor<Integer, String> ------ Subscriber<String>

More at:

https://grokonez.com/java/java-9/java-9-flow-api-example-processor

Java 9 Flow API example – Processor