Reactive Programming, Rxjava and Vert.x

Reactive Programming

Reactive programming is programming with asynchronous data streams.

When using reactive programming, data streams are going to be the spine of your application. Events, messages, calls, and even failures are going to be conveyed by a data stream. With reactive programming, you observe these streams and react when a value is emitted.

Rxjava

Reactive eXtension (http://reactivex.io, aka. RX) is an implementation of the reactive programming principles to “compose asynchronous and event-based programs by using observable sequence”. With RX, your code creates and subscribes to data streams named Observables. While Reactive Programming is about the concepts, RX provides you an amazing toolbox. By combining the observer and iterator patterns and functional idioms, RX gives you superpowers. You have an arsenal of functions to combine, merge, filter, transform and create the data streams. The next picture illustrates the usage of RX in Java (using https://github.com/ReactiveX/RxJava).

RxJava is a popular library for creating asynchronous and event-based programs, it takes inspiration from the main ideas brought forward by the Reactive Extensions initiative.

Vert.x

Vert.x, a project under Eclipse‘s umbrella, offers several components designed from the ground up to fully leverage the reactive paradigm.

Used together with Rxjava, they could prove to be a valid foundation for any Java program that needs to be reactive.

FileSystem fileSystem = vertx.fileSystem();
HttpClient httpClient = vertx.createHttpClient();

Vert.x's FileSystem gives access to the file system in a reactive way, while Vert.x's HttpClient does the same for HTTP.