Call TCP send (net package) from http request function

Issue

I’m new to Go – following problem: My program receives an http post request and now I want to forward data from it to an active TCP connection (the program runs a parallel TCP Server).
In main() the handler is registered like this:
http.HandleFunc("/rcvtelegram", handleRestRequest)

and the http-handler function is therefore like this:

func handleRestRequest(w http.ResponseWriter, r *http.Request) {}

The TCP connection to the client is open with a net.Conn object which main() knows. So ideally I would start a go routine with a TCP sender function that listens for an incoming string to send it through TCP. But how? With channels it seems I must pass all parameters but I don’t have the connection object in the http handler function. I also want to avoid making the tcp connection a global variable. I saw the Observer pattern but that scares me with its complexity as a newbie (and not sure if it solves my problem).

Thanks!

Solution

Use a struct type to hold the channel. Implement the http.Handler interface on the type:

type RestHandler struct {
    ch chan string
}

func (h *RestHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    // insert body of the handleRestRequest here.
    // Use h.ch <- someString to send string to connection
}

In your main function, create a channel for the TCP sender and start the sender in a goroutine:

ch := make(chan string)
go tcpSender(ch)

Create a value of *RestHandler with the channel and register it as the handler:

http.Handle("/rcvtelegram", &RestHandler{ch:ch})

Answered By – Kyle Jones

Answer Checked By – Mildred Charles (GoLangFix Admin)