In this chapter, you learned what a RESTful API is, the architectural constraints of REST, and the details of the REST uniform interface constraint. You also learned the characteristics of the opinionated RESTful API, that is, the Richardson Maturity Model of the RESTful API. We also talked about how being RESTful isn't a religious thing. Be practical.

You also learned about the design procedure of the RESTful API, the implementation support that Spring MVC provides, as well as the use of an HTTP client to consume a RESTful API. Finally, you tested the Message App's /messages API to see how to perform API unit testing.

In the next chapter, you're going to learn how to set up the scaffold of the frontend and the backend. That's where we will start, as we implement the TaskAgile application.