This work, groups the different practices used in the implementation of software components through Rx extensions. These practices are organized into 35 application items, and for each item, it is analyzed, which are the recommended code practices and the practices to avoid.

It could also be said that this document is the compilation of good practices learned through the own experience acquired in business projects, recommendations received from forums, blogs, workshops and in general from analyzes given by experts in the area, including the recommendations given in the official sites of each extension.

This book is also intended as a practical reference manual for implementing Rx code. That is why much of the book's material consists of examples of code snippets written in the main programming languages ​​for both Frontend (mobile, web; that is, JavaScript, Swift, Java) such as Backend.

The concepts studied in each of the items are agnostic to the programming language, there are few cases in which a certain capacity is not available in an extension and in which case the respective annotation is made in the item.

It is intended that once the concepts of each item have been studied, the reader benefits from a greater understanding of how Rx works.

Readers will also be equipped with tools to apply good practices that are ultimately reflected in the solutions in the area of:

- Clean Code.

- Best performance:

- Mitigate bugs scenarios.

I must confess that I had to rethink the edition of the book several times before I managed to structure it to the current version.

The reason was straightforward. While I was writing the book’s content, the announcement appeared for improvements in the architecture components with Jetpack; later, from Kotlin, more powerful tools were introduced, and later enabled Flow Coroutines as an option for reactive programming. As if that were not enough, the introduction of Compose is announced.

Mind Blown!

I did not hesitate twice. We had to reinvent ourselves (yes, also that typical phrase around here).

And it is that Compose and the advent of declarative views in both Android and iOS were inescapable.

Therefore, I decided that for this book to serve as a guide in developing applications for Android, I had to involve the latest and best tools available in the ecosystem to design and implement mobile applications.

I think that the first reader who benefited from this book was me.

It has allowed me to explore and build components differently from how they had been until a few years ago and take advantage of the maximum of these recent changes that both Google and JetBrains have been contributing to the solutions and software development industry.

I have tried to be practical in the presentation of the topics, without much theory, rather, leaving the references for readers to investigate and delve into a particular topic and presenting the code of a project of e-commerce application without going into much detail.

However, leaving the functional and complete source code in a repository for the reader on their own to analyze, digest, and understand in their own time.

I am sincere in admitting that I have been quite excited about the capabilities Compose, Kotlin, Jetpack Components, and these other modern tools provide when implementing a native mobile app.

Once you learn to dominate this set of technologies, there is no going back. This modern style is my first choice of mobile app design, even though I’m older of experience working with the old style.

I admit that it was not easy at the beginning; reviewing and studying a concept several times as necessary until I understood it clearly.

Fortunately, Google’s engineering team has documented and shared vital design guides as an implementation reference, many of which I have referenced in the sections of this book.

Whether you are an experienced developer or new to the arena, this book will provide an initial understanding of adopting the modern style of building native mobile applications for Android.

I hope you like this work and find it helpful and, above all, practical.