Simple Web Server Implementation: GoLang

I am trying to implement a simple web server using Go. I expected "Hello World" to be displayed on the client's browser at the URL "http://127.0.0.1.12000/".

I have tried the following code but ended up with errors.

package main

import "net"
import "fmt"
import "bufio"

// import "strings"
// only needed below for sample processing

func main() {
	fmt.Println("Launching server...")

	// listen on all interfaces
	ln, err := net.Listen("tcp", ":12000")
	if err != nil {
		fmt.Println("Launching error1...")
		return
	}
	// run loop forever (or until ctrl-c)
	for {
		// accept connection on port
		conn, err := ln.Accept()
		if err != nil {
			fmt.Println("Launching error2...")
			return
		}

		// will listen for message to process ending in newline (\n)
		message, err := bufio.NewReader(conn).ReadString('\n')

		if err != nil {
			fmt.Println("Launching error3...")
			newmessage := "Hello World!"
			conn.Write([]byte(newmessage + "\n"))
			return
		}

		// output message received
		fmt.Print("Message Received:", string(message))

		// sample process for string received
		newmessage := "Hello World!"
		conn.Write([]byte(newmessage + "\n"))
	}
}

When I tried to execute the code, the command line shows the following, but there is no output on browser..

Launching server...
Message Received:GET / HTTP/1.1
Message Received:GET / HTTP/1.1

Am I missing anything? Did I make any mistakes?

Just to add some information here.. That that isn't a simple server that you're writing. You're trying to write an HTTP server without the net/http package. This is nontrivial. Perhaps you want an echo server instead?

Your browser wants a properly formatted HTTP response. That means you can't just write a random string to the connection and expect it to know what to do with it. Here is a wikipedia to the HTTP protocol description (I don't intend to describe an entire protocol in a SO answer).

If you want just a bare bones answer that should work:

HTTP/1.1 200 OK
Content-Type: text/plain; charset=UTF-8;
Content-Length: LENGTH OF BODY HERE

BODY

Note that headers are separated by \r\n and the last header is followed by two: \r\n\r\n.

So this:

conn.Write([]byte("HTTP/1.1 200 OK\r\n"))
conn.Write([]byte("Content-Type: text/plain; charset=UTF-8\r\n"))
newmessage := "Hello World!"
conn.Write([]byte("Content-Length: " + strconv.Itoa(len(newmessage)) + "\r\n\r\n"))
conn.Write([]byte(newmessage + "\n"))

Also, I guess since this is a protocol issue I could also let you know that the typical HTTP port is 80 and the alternative/testing one is 8080. Just some added convention for your knowledge I guess.