How it works…

Once we run the program, the HTTP server will start locally listening on port 8080 and accessing http://localhost:8080/, http://localhost:8080/login, and http://localhost:8080/logout from a browser or command line will render the message defined in the corresponding handler definition. For example, execute http://localhost:8080/ from the command line, as follows:

$ curl -X GET -i http://localhost:8080/

This will give us the following response from the server:

We could also execute http://localhost:8080/login from the command line as follows:

$ curl -X GET -i http://localhost:8080/login

This will give us the following response from the server:

Let's understand the program we have written:

1. We started with defining three handlers or web resources, such as the following:

func helloWorld(w http.ResponseWriter, r *http.Request) 
{
  fmt.Fprintf(w, "Hello World!")
}
func login(w http.ResponseWriter, r *http.Request) 
{
  fmt.Fprintf(w, "Login Page!")
}
func logout(w http.ResponseWriter, r *http.Request) 
{
  fmt.Fprintf(w, "Logout Page!")
}

Here, the helloWorld handler writes Hello World! on an HTTP response stream. In a similar way, login and logout handlers write Login Page! and Logout Page! on an HTTP response stream.

2. Next, we registered three URL paths—/, /login, and /logout with DefaultServeMux using http.HandleFunc() . If an incoming request URL pattern matches one of the registered paths, then the corresponding handler is called passing (http.ResponseWriter, *http.Request) as a parameter to it, as follows:

func main() 
{
  http.HandleFunc("/", helloWorld)
  http.HandleFunc("/login", login)
  http.HandleFunc("/logout", logout)
  err := http.ListenAndServe(CONN_HOST+":"+CONN_PORT, nil)
  if err != nil 
  {
    log.Fatal("error starting http server : ", err)
    return
  }
}