hermancain hermancain - 25 days ago 16
HTTP Question

What is an http request multiplexer?

I've been studying golang and I noticed a lot of people create servers by using the

http.NewServeMux()
function and I don't really understand what it does.

I read this:


In go ServeMux is an HTTP request multiplexer. It matches the URL of
each incoming request against a list of registered patterns and calls
the handler for the pattern that most closely matches the URL.


How is that different than just doing something like:

http.ListenAndServe(addr, nil)
http.Handle("/home", home)
http.Handle("/login", login)


What is the purpose of using multiplexing?

Answer

From net/http GoDoc and Source.

ListenAndServe starts an HTTP server with a given address and handler. The handler is usually nil, which means to use DefaultServeMux. Handle and HandleFunc add handlers to DefaultServeMux

DefaultServeMux is just a predefined http.ServeMux

var DefaultServeMux = &defaultServeMux
var defaultServeMux ServeMux

As you can see http.Handle calls DefaultServeMux internally.

func Handle(pattern string, handler Handler) { DefaultServeMux.Handle(pattern, handler) }

The purpose of http.NewServeMux() is to have your own instance of http.Servermux for instances like when you require two http.ListenAndServe functions listening to different ports with different routes.

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