Most programmers are used to the imperative programming style, in which programs are written using a step-by-step approach: the program starts at a certain point, and then branches and loops as necessary, updating things as it goes, depending on which branch it has taken. This approach is not always ideal for complex applications with continually changing inputs.

In reactive programming (not to be confused with ReactJS), by contrast, (almost) everything is coded as a response to a stream of events, or incoming data. We observe, filter, manipulate and otherwise react to various streams, and create new streams as well.

“The core of reactive programming is a data stream that we can observe and react to.” (Kumar Chandrakant, Baeldung)

In this intermediate programming session, we will take a look at reactive programming using RxJS, and a different paradigm for programming in general.