Reactive Programming

Roberto Russo
May 3, 2023
javajava libraryprogrammingreactive programmingreactortech

A general overview of the paradigm

Reactive programming is a programming paradigm that focuses on how data flows through a system and how to react to changes in that data. It is based on the principles of event-driven and asynchronous programming, and it provides a more responsive and resilient way to build software systems. In reactive programming, the emphasis is on building applications that can handle high volumes of data and provide real-time responses to user interactions.

The programming model is based on the concept of reactive streams, which are a set of standardized interfaces and operators for processing and transforming streams of data.

Key benefits

Reactive programming enables developers to build systems that are more scalable, efficient, and fault-tolerant than traditional programming models. By leveraging asynchronous processing and non-blocking I/O, reactive applications can handle more requests with less resources and respond more quickly to user interactions. Reactive programming is gaining popularity in modern software development because it provides a powerful toolset for building responsive and scalable applications. Popular reactive frameworks and libraries include RxJava and Reactor.

Reactor, Flux and Mono

At its core, Reactor provides two key interfaces: Flux and Mono. These interfaces represent sequences of events that can emit zero or more items, and emit either zero or one item, respectively. Flux is similar to a stream of data, while Mono is similar to a future that may or may not complete with a value. Reactor also provides a wide range of operators, such as map, flatMap, filter, and reduce, that allow developers to transform, filter, and combine data streams. These operators can be used to implement complex processing pipelines that handle large volumes of data with minimal resource consumption.

Support for backpressure

Backpressure is a technique used to manage the flow of data in reactive applications. It allows the consumer of a data stream to signal the producer when it is ready to receive more data, ensuring that the consumer is not overwhelmed with data it cannot process. Reactor provides a set of operators, such as buffer, window, and sample, that allow developers to implement backpressure strategies that are tailored to their specific use cases. In addition to its core features, Reactor also provides support for other components and frameworks, such as Spring Framework and Spring Boot. For example, Spring WebFlux, (part of Spring Framework from version 5 and Spring Boot from version 2), is built on top of Reactor and provides a reactive web programming model that enables developers to build highly scalable and efficient web applications.

Code example

Reactive programming example code in Java


In conclusion, Java Reactor is a powerful reactive programming library with its core components, operators, and support for backpressure and reactive streams it’s an ideal choice for building event-driven applications that handle large volumes of data. Its seamless integration with other components and frameworks, such as Spring Framework and Spring Boot, make it a popular choice among Java developers who want to build reactive applications that are easy to develop and maintain.

My personal opinion is that using Reactor has been an interesting experience, in particular I loved the functional programming style which made the code base more readable and easier to maintain. Moreover the usage of Flux and Mono classes were quite intuitive making the reactive streams easy to work with.