In this chapter, we began the development of the Messenger Android application. In the process of doing so, we covered a vast array of topics. We got down and dirty with the Model-View-Presenter pattern and explored in detail how to create an application utilizing this modern development approach.

Further into the chapter, we learned about reactive programming and made extensive use of RxJava and RxAndroid. We learned how to communicate with a remote server using OkHttp and Retrofit, after which we took things one step further and implemented a fully functional Retrofit service to communicate with the Messenger API we developed in Chapter 4, Designing and Implementing the Messenger Backend with Spring Boot 2.0.

In the next chapter, we will finish our work with the Messenger application.