Starting from this chapter, we are going to walk through the concrete implementation of the web service part using .NET Core. We will cover some key aspects of developing real web services—from the design of the data access layer to the implementation of the HTTP routes. 

In this chapter, we will start by defining the data access part. The data access part is necessary to store information in a database or data source, and it is usually one of the most delicate parts of an application. We will be focusing on the implementation of a catalog web service. Additionally, we will explore different third-party tools for accessing our data and explain how to set up a project and implement a data domain.

This chapter will cover the following topics:

• Designing project entities
• Choosing the right tool
• Implementing a data access layer using EF Core
• Implementing a data access layer using Dapper
• Testing a data layer using the in-memory database