Thanks for buying this guide to Reactive Programming and Reactive Extensions for .NET.

This book will give you an expert overview about the magical world of programming, also known as programming live data or real-time data, instead of programming static data as happens with any other usual programming paradigm.

Do you know Microsoft Excel?

Excel is a software that lets you write raw numbers and functions in a proprietary mathematical form or through a simple scripting programming language (VBA).

The magic happens when you write an Excel function, such as =A1+A2, which means that the current cell value will be the sum of the values contained in the A1 and A2 cells.

This simple function creates a subscription to the events of cells A1 and A2. This means that any time you update the value of any of these two cells, the function will return a new value. This is the simplest example of functional and reactive programming available.

Now that we have an idea of what reactive is, it is easy to explain that this book will guide developers with any background knowledge about reactive programming toward the understanding of the reactive programming paradigm with a lot of examples of using Reactive Extensions (Rx) for .NET.

This chapter will give an overview of what Reactive Programming (RP) is and how it works, starting with programming paradigms and later diving into the RP structure following the schema: