In this chapter, we first introduced the HTTP router. We tried to build a basic application using Go's http package. Then we briefly discussed ServeMux, with an example. We saw how to add multiple handlers to multiple routes. Then we introduced a lightweight router package called httprouter. httprouter allows developers to create scalable routes, with the option of parsing parameters passed in the URL path. We can also serve files over the HTTP using httprouter. We built a small service to get the Go version and file contents (read-only). That example can be extended to any system information.

Next, we introduced the popular Go routing library: Gorilla Mux. We discussed how it is different from httprouter and explored its functionality by implementing solid examples. We explained how Vars can be used to get path parameters and r.URL.Query to parse query parameters. Then we discussed SQL injection and how it can happen in our applications. We gave a few pointers on how to avoid it. We will see some of these measures in upcoming chapters when we build a complete REST service, which includes a database. Finally, we laid down the logic for URL shortening and created an API design document.

In the next chapter, we look at Middleware functions, which act as tamperers for HTTP requests and responses. That phenomenon will help us modify the API response on-the-fly. The next chapter also features RPC (Remote Procedure Call).