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App Development
6 minutes read

What Is Reactive Programming? 

By Alvaro Insignares
Reactive programming
By Alvaro Insignares
App Development
6 minutes read

Reactive programming responds to changes in data streams in a manner that is more aligned with the expectations of modern application users. Today, users demand applications that are not just functional but also highly responsive in real-time. 

Reactive programming, sometimes called functional reactive programming, is a development paradigm that has become prominent in recent years for addressing this growing user expectation. 

It offers a powerful way to build applications and reactive systems that can respond to changing data and events seamlessly and efficiently. 

This post will delve into reactive programming and why it benefits modern software development.

A Closer Look at Reactive Programming

Reactive programming is a development paradigm that focuses on building applications that react to changes in data and events as they occur. This development model is built around asynchronous data streams. 

Reactive programming is primarily concerned with modeling the flow of data and events in a manner that simplifies asynchronous stream processing and delivers responsive user interfaces. 

Reactive programming is all about reacting to changes in data or events in a more organized and efficient manner than traditional programming paradigms. A simple way to understand reactive programming is through an example. 

Imagine you have several sensors in a smart home that detect temperature, humidity, and light levels. Using traditional programming paradigms, you have to constantly check the values of these sensors to see if there has been a change. 

If there has been a change, the corresponding action must then be taken. This process is not only inefficient, but it can also be error-prone.

With reactive programming, a system is created where you declare what should happen when the sensor values change. Rules or “reactive” behaviors are predefined.

For example, you might create a rule where the air conditioner is turned on if the temperature goes above 75 degrees. Reactive programming enables the system to react to changes in sensor values based on predefined rules without constantly polling the values of the sensors. 

Reactive programming is most useful in scenarios where event streams or data changes are frequent and need to be handled efficiently. 

The Vital Elements of Reactive Programming

Understanding the inherent elements of the reactive programming paradigm will help you understand how this paradigm fits into the software development world and differs from object-oriented programming, which is more of a language design than a programming paradigm.

The core elements of the reactive programming paradigm are:

  • Observables 
  • Subscribers 
  • Operators 
  • Asynchronicity 


At the heart of reactive programming are observables, which are streams of data or events. Observables represent a sequence of values that can change over time. They allow programmers to listen for and react to changes in multiple streams of data.


Subscribers are entities that subscribe to observables to receive updates whenever the observable emits new data or events. Subscribers can then react to these updates. This quality is useful in a transaction processing system to validate a purchase or state and react accordingly. 


Operators are functions that can be applied to observables to transform, filter, or combine them in various ways. They allow for powerful data manipulation and processing capabilities, without which it would be difficult to produce many of the functions users have come to expect in applications. 


Reactive programming deals effectively with asynchronous operations, making it suitable for handling events, user interactions, and data from external sources like APIs or databases.

Modern reactive programs generate parallel processing activity and rely on automated data streams to deliver the functionality modern users have come to expect from their applications. 

What Is Reactive Streams? 

Reactive Streams is a programming initiative and a set of interfaces that provide a non-blocking, backpressure-aware way to work with asynchronous data streams

The Reactive Streams initiative began in late 2013 with engineers from Netflix, Lightbend, and Pivotal. Lightbend continues to be one of the main contributors to Reactive Streams, with additional contributions from the teams at Oracle and Red Hat.

Reactive Streams were introduced to address some of the challenges associated with managing and processing asynchronous data streams, such as those encountered in real-time data processing, web services, and other event-driven systems. 

They aim to provide a standardized way to:

  • Handle asynchronous data
  • Avoid resource exhaustion
  • Compose operations on data streams
  • Support additional programming languages and platforms 

The Benefits of Reactive Programming

There are several benefits associated with reactive programming. However, a few benefits rise above the rest and should be noted here. The top benefits of reactive programming include:

  • Responsiveness 
  • Scalability 
  • Error handling 
  • Readability 
  • Widely compatible 


Reactive programming enables the creation of highly responsive applications. With observables and subscribers, you can react to changes in real time, providing users with a smoother and more interactive experience.

Most consumers now expect this responsive, interactive user experience from their applications. Reactive programming is an important paradigm to follow if you want to continue to deliver an experience that meets or exceeds users’ expectations. 


Reactive programming is ideal for building scalable systems. This paradigm allows you to efficiently handle concurrent requests and events, making it ideal for high-traffic applications and demanding workloads.

Modern businesses understand that demand can grow quickly. As a result, it is critical to utilize technologies and approaches that can scale when required. Don’t let a lack of scalability hold back your applications and organization. 

Error Handling

The reactive paradigm provides robust error-handling mechanisms, making it easier to manage and recover from unexpected issues in your application. Coding errors are bound to happen in every application development project. 

Reactive programming makes it easier for your team to address and recover from errors. Errors can be costly and lead to significant time delays. Do everything you can to minimize their impact. 


Reactive programming can deliver more readable code. You can often write more readable and maintainable code by modeling your code around observable streams and declarative operators. This makes it easier for developers to understand and modify the logic as the application evolves.

Widely Compatible 

Reactive programming libraries and frameworks are available for a variety of programming languages, enabling the use of this paradigm across different platforms and environments.

Reactive programming is not a specific language but a programming paradigm. This paradigm’s compatibility with the most popular languages, frameworks, and libraries enables a wide range of developers to utilize this powerful approach. 

Final Thoughts 

Reactive programming is a powerful paradigm that offers numerous benefits for modern software development. It enables the creation of responsive, scalable, and maintainable applications by modeling data and events as observable streams. 

By embracing reactive programming and utilizing the appropriate libraries and frameworks, developers can build applications that meet the high expectations of today’s users in terms of performance and responsiveness. As technology continues to evolve, reactive programming will likely play an even more significant role in shaping the future of software development.

If you want to learn more about reactive programming and how it could benefit your organization’s applications, contact an experienced app development partner like Koombea.

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