In this chapter, we'll continue building our GoMusic web application. This chapter will cover some advanced concepts, as it will add to what we built in the previous chapter before it dives deeper into how to build advanced backend software. We will cover some important and practical topics such as database layers for connecting our application to a production database, object-relational mapping (ORM) for simplifying our database layer code, middleware for adding functionality on top of our Web API handlers, authentication to secure our web application, and credit card charging. We will also revisit the frontend of our GoMusic application in order to cover how our frontend would connect to our backend.

Specifically, we'll cover the following topics in this chapter:

• Database layers and ORMs
• Middleware
• Security, authentication, and authorization
• Credit card charging
• Proxying React applications
• Authorizing and authenticating from React applications

This chapter will revisit the frontend layer of our application, in order to evolve our existing React application to utilize the new backend features.