In this chapter, you have learned how to build web APIs for your applications for integration purposes and for loosely coupled application architectures.

We have explored different three styles for our web APIs, that is, RPC, REST, and HATEOAS. Each of those styles has specific advantages and use cases. You have to choose carefully, depending on your specific application needs, since there is no one single style that outclasses the others.

Throughout this chapter, we've looked at examples of how to transform existing controller actions into RPC-style web APIs and how to build REST-style and HATEOAS-style web APIs from the ground up. Then, we used Postman to manually test our web APIs and you have acquired enough knowledge to apply all of these new concepts to your own environments. Finally, we used OpenAPI's Swagger to automatically produce documentation for our API endpoints.

To summarize, we've learned how to build REST APIs, acquired skills in terms of how to transform a controller action into an RPC-style web API, and built them from scratch. We also learned how to build HATEOAS-style web APIs and configure our APIs so that they have a help page with API specification documentation.

In the next chapter, we will talk about how to access data by using Entity Framework Core 3 in our ASP.NET Core 3 applications.