Hello World socket server

Question

Write the shortest program that answers "Hello, World" to a network connection.

Conditions:

• Program shall listen on port 12345
• When a client connects, program shall write "Hello, World" to the newly opened socket connection and then close the connection
• Program shall accept connections in a loop, i.e. handle any number of connects
• Program does not need to handle parallel connections

Test:

prompt> telnet localhost 12345
Hello, World
prompt>

Answer 1

Bash (34)

nc -l 12345 <<<Hello,\ World;. $0

Answer 2

Java, 268 Bytes

import java.io.*;import java.net.*;
class S{public static void main(String[]args)throws Exception{ServerSocket s=new ServerSocket(12345);while(1>0){Socket t=s.accept();PrintWriter u=new PrintWriter(t.getOutputStream());u.println("Hello World!");u.flush();t.close();}}}

Ungolfed:

import java.io.*;import java.net.*;
class S{
    public static void main(String[]args)throws Exception{
        ServerSocket s = new ServerSocket(12345);
        while(true) {
            Socket t = s.accept();
            PrintWriter u = new PrintWriter(t.getOutputStream()) ;
            u.println("Hello World!");
            u.flush();
            t.close();
        }
        s.close();
    }
}

Answer 3

Clojure, 153 148 bytes

-5 byte using macros. See comments.

(let[s(java.net.ServerSocket. 12345)](while 1(with-open[c(.accept s)](doto(java.io.PrintWriter.(.getOutputStream c))(.write"Hello, World").flush))))

Full program that listens in a loop for incoming connections, and outputs as required. The Java-interop is killer here. I don't need the same libraries enough to justify an import though.

Pregolfed:

(defn server []
  (let [ss (java.net.ServerSocket. 12345)]
    (while 1
      ; Auto closes the client
      (with-open [c (.accept ss)]
         ; Passes the PrintWriter as the first argument to each function
         (doto (java.io.PrintWriter. (.getOutputStream c))
           (.write "Hello, World\n")
           ; Parentheses are optional if the function only takes 1 argument
           ; Ugly, but shorter
           .flush)))))

Answer 4

Groovy, 119 bytes

{s=new java.net.ServerSocket(12345);while(1){(u=(t=s.accept()).getOutputStream())<<"Hello, World";u.flush();t.close()}}

Port of my java answer.

Answer 5

Racket, 111 bytes

(do([l(tcp-listen 12345)])(#f)(let-values([(i o)(tcp-accept l)])(display"Hello, World"o)(close-output-port o)))

It always surprises me when the do form is shorter than explicit recursion. I'm not entirely certain if I'm required to close the input port. Please comment if you think I need to.

Ungolfed

(do ([l (tcp-listen 12345)]) (#f)
  (let-values ([(i o) (tcp-accept l)])
    (display "Hello, World" o)
    (close-output-port o)))

Answer 6

Python, 103

import socket
s=socket.socket()
s.bind(('',12345))
s.listen(1)
s.accept()[0].sendall(b'Hello, World')

Answer 7

Tcl, 78 chars

socket -server r 12345;proc r {s a b} {puts $s Hello,\ World;close $s};vwait r

the vwait r enters the event loop (not necessary with Tk) until the variable r is set. Usually you use the variable forever.
And the Hello,\ World is the same as {Hello, World} or "Hello, World"

Answer 8

Go 133

package main
import(n"net")
func main(){l,_:=n.Listen("tcp",":12345")
for{c,_:=l.Accept()
c.Write([]byte("Hello, World"))
c.Close()}}

Answer 9

LiveScript (node.js), 73 bytes

(require(\net)createServer ->it.write 'Hello, World';it.end!)listen 12345

Answer 10

C# 220

using System.Text;namespace System.Net.Sockets{class P{static void Main(){var s=new TcpListener(IPAddress.Any,12345);s.Start();while(true){using(var c=s.AcceptSocket()){c.Send(Encoding.UTF8.GetBytes("Hello World"));}}}}}

Ungolfed:

using System.Text;
namespace System.Net.Sockets
{
    class P
    {
        static void Main()
        {
            var s = new TcpListener(IPAddress.Any, 12345);
            s.Start();
            while (true)
            {
                using (var c = s.AcceptSocket())
                {
                    c.Send(Encoding.UTF8.GetBytes("Hello World"));
                }
            }
        }
    }
}

Pretty straightforward. I could have saved 14 characters by removing IPAddress.Any, but that would rely on using deprecated API ...

Answer 11

Perl, 118 bytes

$s=new IO::Socket::INET LocalPort=>12345,Listen=>5,Reuse=>1;{$c=$s->accept;$c->send("Hello World");shutdown $c,1;redo}

Example:

$ perl -MIO::Socket -e '$s=new IO::Socket::INET LocalPort=>12345,Listen=>5,Reuse=>1;{$c=$s->accept;$c->send("Hello World");shutdown $c,1;redo}'

$ telnet localhost 12345
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Hello WorldConnection closed by foreign host.
$

Answer 12

Wolfram (102)

#[[2]] contains OutputStream of the incoming socket

<<SocketLink`;
CreateAsynchronousServer[CreateServerSocket@12345,(#[[2]]~Write~"Hello world";Close/@#)&]

Answer 13

Ruby, 83 bytes

require'socket';s=TCPServer.new 12345;loop{t=s.accept;t<<"Hello, World\n";t.close}