Chat server: Difference between revisions

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People should be able to connect via ‘telnet’, sign on with a nickname, and type messages which will then be seen by all other connected users. Arrivals and departures of chat members should generate appropriate notification messages.
<br><br>
 
=={{header|Ada}}==
{{libheader|AdaSockets}}
 
<langsyntaxhighlight Adalang="ada">with Ada.Containers.Vectors;
with Ada.Command_Line; use Ada.Command_Line;
with Ada.Exceptions; use Ada.Exceptions;
Line 94 ⟶ 93:
Dummy.Start (Incoming_Socket);
end loop;
end Chat_Server;</langsyntaxhighlight>
 
=={{header|BaConBASIC}}==
==={{header|BaCon}}===
Requires BaCon 4.2 or higher. Clients have to login with an alias and can use the commands 'say' or 'quit'. Notifications are submitted when users enter the chat or leave the chat.
<syntaxhighlight lang="text">DECLARE user$ ASSOC STRING
DECLARE connect ASSOC long
OPEN "localhost:51000" FOR SERVER AS mynet
Line 132:
ENDIF
ENDIF
WEND</langsyntaxhighlight>
 
==={{header|Visual Basic .NET}}===
{{trans|C#}}
<syntaxhighlight lang="vbnet">Imports System.Net.Sockets
Imports System.Text
Imports System.Threading
 
Module Module1
 
Class State
Private ReadOnly client As TcpClient
Private ReadOnly sb As New StringBuilder
 
Public Sub New(name As String, client As TcpClient)
Me.Name = name
Me.client = client
End Sub
 
Public ReadOnly Property Name As String
 
Public Sub Send(text As String)
Dim bytes = Encoding.ASCII.GetBytes(String.Format("{0}" & vbCrLf, text))
client.GetStream().Write(bytes, 0, bytes.Length)
End Sub
End Class
 
ReadOnly connections As New Dictionary(Of Integer, State)
Dim listen As TcpListener
Dim serverThread As Thread
 
Sub Main()
listen = New TcpListener(Net.IPAddress.Parse("127.0.0.1"), 4004)
serverThread = New Thread(New ThreadStart(AddressOf DoListen))
serverThread.Start()
End Sub
 
Private Sub DoListen()
listen.Start()
Console.WriteLine("Server: Started server")
 
Do
Console.Write("Server: Waiting...")
Dim client = listen.AcceptTcpClient()
Console.WriteLine(" Connected")
 
' New thread with client
Dim clientThread As New Thread(New ParameterizedThreadStart(AddressOf DoClient))
 
clientThread.Start(client)
Loop
End Sub
 
Private Sub DoClient(client As TcpClient)
Console.WriteLine("Client (Thread: {0}): Connected!", Thread.CurrentThread.ManagedThreadId)
Dim bytes = Encoding.ASCII.GetBytes("Enter name: ")
client.GetStream().Write(bytes, 0, bytes.Length)
 
Dim done As Boolean
Dim name As String
Do
If Not client.Connected Then
Console.WriteLine("Client (Thread: {0}): Terminated!", Thread.CurrentThread.ManagedThreadId)
client.Close()
Thread.CurrentThread.Abort() ' Kill thread
End If
 
name = Receive(client)
done = True
 
For Each cl In connections
Dim state = cl.Value
If state.Name = name Then
bytes = Encoding.ASCII.GetBytes("Name already registered. Please enter your name: ")
client.GetStream().Write(bytes, 0, bytes.Length)
done = False
End If
Next
Loop While Not done
 
connections.Add(Thread.CurrentThread.ManagedThreadId, New State(name, client))
Console.WriteLine(vbTab & "Total connections: {0}", connections.Count)
Broadcast(String.Format("+++ {0} arrived +++", name))
 
Do
Dim text = Receive(client)
If text = "/quit" Then
Broadcast(String.Format("Connection from {0} closed.", name))
connections.Remove(Thread.CurrentThread.ManagedThreadId)
Console.WriteLine(vbTab & "Total connections: {0}", connections.Count)
Exit Do
End If
 
If Not client.Connected Then
Exit Do
End If
 
Broadcast(String.Format("{0}> {1}", name, text))
Loop
 
Console.WriteLine("Client (Thread: {0}): Terminated!", Thread.CurrentThread.ManagedThreadId)
client.Close()
Thread.CurrentThread.Abort()
End Sub
 
Private Function Receive(client As TcpClient) As String
Dim sb As New StringBuilder
Do
If client.Available > 0 Then
While client.Available > 0
Dim ch = Chr(client.GetStream.ReadByte())
If ch = vbCr Then
' ignore
Continue While
End If
If ch = vbLf Then
Return sb.ToString()
End If
sb.Append(ch)
End While
 
' pause
Thread.Sleep(100)
End If
Loop
End Function
 
Private Sub Broadcast(text As String)
Console.WriteLine(text)
For Each client In connections
If client.Key <> Thread.CurrentThread.ManagedThreadId Then
Dim state = client.Value
state.Send(text)
End If
Next
End Sub
 
End Module</syntaxhighlight>
 
=={{header|C}}==
Line 141 ⟶ 278:
A glitch occurs if a connection is made using the Telnet protocol - user names are preceded by garbled text.
 
<langsyntaxhighlight lang="c">#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
Line 388 ⟶ 525:
 
return 0;
}</langsyntaxhighlight>
 
=={{header|C sharp|C#}}==
<langsyntaxhighlight lang="csharp">using System;
using System.Collections.Generic;
using System.Net.Sockets;
Line 534 ⟶ 670:
}
}
}</langsyntaxhighlight>
 
=={{header|CoffeeScript}}==
This is ported from the JavaScript version. The tool js2coffee got me a mostly working version, and then I manually converted JS-style classes to CS "classic-style class" syntax.
 
<langsyntaxhighlight lang="coffeescript">
net = require("net")
sys = require("sys")
Line 647 ⟶ 782:
 
server = new ChatServer()
</syntaxhighlight>
</lang>
 
=={{header|D}}==
<lang d>
import std.getopt;
import std.socket;
import std.stdio;
import std.string;
 
struct client {
int pos;
char[] name;
char[] buffer;
Socket socket;
}
 
void broadcast(client[] connections, size_t self, const char[] message) {
writeln(message);
for (size_t i = 0; i < connections.length; i++) {
if (i == self) continue;
 
connections[i].socket.send(message);
connections[i].socket.send("\r\n");
}
}
 
bool registerClient(client[] connections, size_t self) {
for (size_t i = 0; i < connections.length; i++) {
if (i == self) continue;
 
if (icmp(connections[i].name, connections[self].name) == 0) {
return false;
}
}
 
return true;
}
 
void main(string[] args) {
ushort port = 4004;
 
auto helpInformation = getopt
(
args,
"port|p", "The port to listen to chat clients on [default is 4004]", &port
);
 
if (helpInformation.helpWanted) {
defaultGetoptPrinter("A simple chat server based on a task in rosettacode.", helpInformation.options);
return;
}
 
auto listener = new TcpSocket();
assert(listener.isAlive);
listener.blocking = false;
listener.bind(new InternetAddress(port));
listener.listen(10);
writeln("Listening on port: ", port);
 
enum MAX_CONNECTIONS = 60;
auto socketSet = new SocketSet(MAX_CONNECTIONS + 1);
client[] connections;
 
while(true) {
socketSet.add(listener);
 
foreach (con; connections) {
socketSet.add(con.socket);
}
 
Socket.select(socketSet, null, null);
 
for (size_t i = 0; i < connections.length; i++) {
if (socketSet.isSet(connections[i].socket)) {
char[1024] buf;
auto datLength = connections[i].socket.receive(buf[]);
 
if (datLength == Socket.ERROR) {
writeln("Connection error.");
} else if (datLength != 0) {
if (buf[0] == '\n' || buf[0] == '\r') {
if (connections[i].buffer == "/quit") {
connections[i].socket.close();
if (connections[i].name.length > 0) {
writeln("Connection from ", connections[i].name, " closed.");
} else {
writeln("Connection from ", connections[i].socket.remoteAddress(), " closed.");
}
 
connections[i] = connections[$-1];
connections.length--;
i--;
 
writeln("\tTotal connections: ", connections.length);
continue;
} else if (connections[i].name.length == 0) {
connections[i].buffer = strip(connections[i].buffer);
if (connections[i].buffer.length > 0) {
connections[i].name = connections[i].buffer;
if (registerClient(connections, i)) {
connections.broadcast(i, "+++ " ~ connections[i].name ~ " arrived +++");
} else {
connections[i].socket.send("Name already registered. Please enter your name: ");
connections[i].name.length = 0;
}
} else {
connections[i].socket.send("A name is required. Please enter your name: ");
}
} else {
connections.broadcast(i, connections[i].name ~ "> " ~ connections[i].buffer);
}
connections[i].buffer.length = 0;
} else {
connections[i].buffer ~= buf[0..datLength];
}
} else {
try {
if (connections[i].name.length > 0) {
writeln("Connection from ", connections[i].name, " closed.");
} else {
writeln("Connection from ", connections[i].socket.remoteAddress(), " closed.");
}
} catch (SocketException) {
writeln("Connection closed.");
}
}
}
}
 
if (socketSet.isSet(listener)) {
Socket sn = null;
scope(failure) {
writeln("Error accepting");
 
if (sn) {
sn.close();
}
}
sn = listener.accept();
assert(sn.isAlive);
assert(listener.isAlive);
 
if (connections.length < MAX_CONNECTIONS) {
client newclient;
 
writeln("Connection from ", sn.remoteAddress(), " established.");
sn.send("Enter name: ");
 
newclient.socket = sn;
connections ~= newclient;
 
writeln("\tTotal connections: ", connections.length);
} else {
writeln("Rejected connection from ", sn.remoteAddress(), "; too many connections.");
sn.close();
assert(!sn.isAlive);
assert(listener.isAlive);
}
}
 
socketSet.reset();
}
}
</lang>
 
=={{header|Common Lisp}}==
{{libheader|usocket}}
Line 835 ⟶ 806:
*USER-MANAGER*, or upon an error occurring.
 
<langsyntaxhighlight lang="common-lisp">
(ql:quickload '(:usocket :simple-actors :bordeaux-threads))
 
Line 1,011 ⟶ 982:
 
(make-thread #'accept-connections)
</syntaxhighlight>
</lang>
=={{header|D}}==
<syntaxhighlight lang="d">
import std.getopt;
import std.socket;
import std.stdio;
import std.string;
 
struct client {
int pos;
char[] name;
char[] buffer;
Socket socket;
}
 
void broadcast(client[] connections, size_t self, const char[] message) {
writeln(message);
for (size_t i = 0; i < connections.length; i++) {
if (i == self) continue;
 
connections[i].socket.send(message);
connections[i].socket.send("\r\n");
}
}
 
bool registerClient(client[] connections, size_t self) {
for (size_t i = 0; i < connections.length; i++) {
if (i == self) continue;
 
if (icmp(connections[i].name, connections[self].name) == 0) {
return false;
}
}
 
return true;
}
 
void main(string[] args) {
ushort port = 4004;
 
auto helpInformation = getopt
(
args,
"port|p", "The port to listen to chat clients on [default is 4004]", &port
);
 
if (helpInformation.helpWanted) {
defaultGetoptPrinter("A simple chat server based on a task in rosettacode.", helpInformation.options);
return;
}
 
auto listener = new TcpSocket();
assert(listener.isAlive);
listener.blocking = false;
listener.bind(new InternetAddress(port));
listener.listen(10);
writeln("Listening on port: ", port);
 
enum MAX_CONNECTIONS = 60;
auto socketSet = new SocketSet(MAX_CONNECTIONS + 1);
client[] connections;
 
while(true) {
socketSet.add(listener);
 
foreach (con; connections) {
socketSet.add(con.socket);
}
 
Socket.select(socketSet, null, null);
 
for (size_t i = 0; i < connections.length; i++) {
if (socketSet.isSet(connections[i].socket)) {
char[1024] buf;
auto datLength = connections[i].socket.receive(buf[]);
 
if (datLength == Socket.ERROR) {
writeln("Connection error.");
} else if (datLength != 0) {
if (buf[0] == '\n' || buf[0] == '\r') {
if (connections[i].buffer == "/quit") {
connections[i].socket.close();
if (connections[i].name.length > 0) {
writeln("Connection from ", connections[i].name, " closed.");
} else {
writeln("Connection from ", connections[i].socket.remoteAddress(), " closed.");
}
 
connections[i] = connections[$-1];
connections.length--;
i--;
 
writeln("\tTotal connections: ", connections.length);
continue;
} else if (connections[i].name.length == 0) {
connections[i].buffer = strip(connections[i].buffer);
if (connections[i].buffer.length > 0) {
connections[i].name = connections[i].buffer;
if (registerClient(connections, i)) {
connections.broadcast(i, "+++ " ~ connections[i].name ~ " arrived +++");
} else {
connections[i].socket.send("Name already registered. Please enter your name: ");
connections[i].name.length = 0;
}
} else {
connections[i].socket.send("A name is required. Please enter your name: ");
}
} else {
connections.broadcast(i, connections[i].name ~ "> " ~ connections[i].buffer);
}
connections[i].buffer.length = 0;
} else {
connections[i].buffer ~= buf[0..datLength];
}
} else {
try {
if (connections[i].name.length > 0) {
writeln("Connection from ", connections[i].name, " closed.");
} else {
writeln("Connection from ", connections[i].socket.remoteAddress(), " closed.");
}
} catch (SocketException) {
writeln("Connection closed.");
}
}
}
}
 
if (socketSet.isSet(listener)) {
Socket sn = null;
scope(failure) {
writeln("Error accepting");
 
if (sn) {
sn.close();
}
}
sn = listener.accept();
assert(sn.isAlive);
assert(listener.isAlive);
 
if (connections.length < MAX_CONNECTIONS) {
client newclient;
 
writeln("Connection from ", sn.remoteAddress(), " established.");
sn.send("Enter name: ");
 
newclient.socket = sn;
connections ~= newclient;
 
writeln("\tTotal connections: ", connections.length);
} else {
writeln("Rejected connection from ", sn.remoteAddress(), "; too many connections.");
sn.close();
assert(!sn.isAlive);
assert(listener.isAlive);
}
}
 
socketSet.reset();
}
}
</syntaxhighlight>
=={{header|Erlang}}==
<langsyntaxhighlight lang="erlang">
-module(chat).
 
Line 1,078 ⟶ 1,210:
Response -> Response
end.
</syntaxhighlight>
</lang>
 
=={{header|Go}}==
This example uses the Go idiom of [http://blog.golang.org/share-memory-by-communicating ''Do not communicate by sharing memory; instead, share memory by communicating'']; there are no explicit locks used, instead Go channels are used to safely synchronize where required.
Line 1,087 ⟶ 1,218:
This example handles the case of one specific client "falling behind" by relying on the underlying TCP stack to do a reasonable job of buffering. Once that buffer fills, a write to the that client's connection will time out and the connection will dropped. Other minor improvements would include enabling TCP keep alives, handling temporary errors from accept, and better logging. Not ideal, but it should be good enough for this example.
 
<langsyntaxhighlight lang="go">package main
 
import (
Line 1,268 ⟶ 1,399:
}
c.server.rem <- c.name
}</langsyntaxhighlight>
 
=={{header|Groovy}}==
{{trans|Java}}
<langsyntaxhighlight lang="groovy">class ChatServer implements Runnable {
private int port = 0
private List<Client> clientList = new ArrayList<>()
Line 1,427 ⟶ 1,557:
new ChatServer(port).run()
}
}</langsyntaxhighlight>
 
=={{header|Haskell}}==
<langsyntaxhighlight lang="haskell">{-# LANGUAGE OverloadedStrings #-}
import Network
import System.IO
Line 1,514 ⟶ 1,643:
T.putStrLn "Server started"
newMVar (M.empty) >>= clientLoop server
</syntaxhighlight>
</lang>
 
==Icon and {{header|Unicon}}==
 
This is Unicon-specific:
<langsyntaxhighlight lang="unicon">global mlck, nCons, cons
 
procedure main()
Line 1,545 ⟶ 1,674:
critical mlck: nCons -:= 1
}
end</langsyntaxhighlight>
 
=={{header|Java}}==
 
Line 1,553 ⟶ 1,681:
I think ideally, NIO would be used to select() sockets available/ready for I/O, to eliminate the possibility of a bad connection disrupting the server, but this increases the complexity.
 
<langsyntaxhighlight lang="java">import java.io.*;
import java.net.*;
import java.util.*;
Line 1,705 ⟶ 1,833:
}
}
</syntaxhighlight>
</lang>
 
=={{header|JavaScript}}==
{{works with|Node.js}}
<langsyntaxhighlight lang="javascript">const net = require("net");
const EventEmitter = require("events").EventEmitter;
Line 1,856 ⟶ 1,983:
// Start the server!
server = new ChatServer();</langsyntaxhighlight>
 
=={{header|Julia}}==
Modified to fit the Rosetta Code task from example code for the WebSockets module written by Leah Hanson.
To test, start the code and use a browser to connect to localhost:8000.
<langsyntaxhighlight lang="julia">
using HttpServer
using WebSockets
Line 1,944 ⟶ 2,070:
println("Chat server listening on 8000...")
run(server,8000)
</syntaxhighlight>
</lang>
 
=={{header|Kotlin}}==
{{trans|Java}}
<langsyntaxhighlight lang="scala">import java.io.BufferedReader
import java.io.IOException
import java.io.InputStreamReader
Line 2,100 ⟶ 2,225:
}
}
}</langsyntaxhighlight>
 
=={{header|Nim}}==
<langsyntaxhighlight lang="nim">import asyncnet, asyncdispatch
 
type
Line 2,144 ⟶ 2,268:
 
asyncCheck serve()
runForever()</langsyntaxhighlight>
 
=={{header|Objeck}}==
<langsyntaxhighlight lang="objeck">
use System.IO.Net;
use System.Concurrency;
Line 2,257 ⟶ 2,380:
}
}
</syntaxhighlight>
</lang>
 
=={{header|Ol}}==
<langsyntaxhighlight lang="scheme">
(define (timestamp) (syscall 201 "%c"))
 
Line 2,329 ⟶ 2,451:
 
(run 8080)
</syntaxhighlight>
</lang>
{{Out}}
 
Line 2,384 ⟶ 2,506:
(127.0.0.1 . 55320): see you..
</pre>
 
=={{header|Perl}}==
{{trans|Python}}
<langsyntaxhighlight lang="perl">use 5.010;
use strict;
use warnings;
Line 2,494 ⟶ 2,615:
 
sleep(0.1);
}</langsyntaxhighlight>
===Alternate with both read and write queuing===
<langsyntaxhighlight lang="perl">#!/usr/bin/perl
 
use strict; # http://www.rosettacode.org/wiki/Chat_server
Line 2,575 ⟶ 2,696:
}
}
}</langsyntaxhighlight>
 
=={{header|Phix}}==
===server===
<!--<langsyntaxhighlight Phixlang="phix">(notonline)-->
<span style="color: #000080;font-style:italic;">--
-- demo\rosetta\ChatServer.exw
Line 2,749 ⟶ 2,869:
<span style="color: #7060A8;">IupMainLoop</span><span style="color: #0000FF;">()</span>
<span style="color: #7060A8;">IupClose</span><span style="color: #0000FF;">()</span>
<!--</langsyntaxhighlight>-->
===client===
<!--<langsyntaxhighlight Phixlang="phix">(notonline)-->
<span style="color: #000080;font-style:italic;">--
-- demo\rosetta\ChatClient.exw
Line 2,993 ⟶ 3,113:
<span style="color: #7060A8;">IupMainLoop</span><span style="color: #0000FF;">()</span>
<span style="color: #7060A8;">IupClose</span><span style="color: #0000FF;">()</span>
<!--</langsyntaxhighlight>-->
 
=={{header|PicoLisp}}==
<langsyntaxhighlight PicoLisplang="picolisp">#!/usr/bin/picolisp /usr/lib/picolisp/lib.l
 
(de chat Lst
Line 3,023 ⟶ 3,142:
(tell 'chat "--- " *Name " left ---")
(bye) ) ) )
(wait)</langsyntaxhighlight>
After starting the above script, connect to the chat server from two terminals:
<pre> Terminal 1 | Terminal 2
Line 3,055 ⟶ 3,174:
| Connection closed.
| $</pre>
 
=={{header|Prolog}}==
Works with Swi-Prolog as of Jan 2019.
 
This version will load the server automatically on port 5000, adapt to your needs.
<langsyntaxhighlight lang="prolog">:- initialization chat_server(5000).
 
chat_server(Port) :-
Line 3,140 ⟶ 3,258:
msg_username_taken('That username is already taken, choose another\n\r').
msg_new_line('\n\r').
msg_by_user('~w> ~w').</langsyntaxhighlight>
 
=={{header|Python}}==
<langsyntaxhighlight lang="python">#!/usr/bin/env python
 
import socket
Line 3,220 ⟶ 3,337:
time.sleep(.1)
except (SystemExit, KeyboardInterrupt):
break</langsyntaxhighlight>
 
=={{header|R}}==
This implementation relies on the new server socket connection type introduced in R 4.0.0.
<syntaxhighlight lang="r">
<lang R>
chat_loop <- function(server, sockets, delay = 0.5) {
repeat {
Line 3,370 ⟶ 3,486:
}
 
start_chat_server()</langsyntaxhighlight>
 
=={{header|Racket}}==
 
This is a very basic chat server, but it does everything that is needed for this task.
 
<langsyntaxhighlight lang="racket">
#lang racket
 
Line 3,398 ⟶ 3,513:
(void (thread (λ() (chat-server (tcp-listen 12321)))))
((client (current-input-port) (current-output-port)))
</syntaxhighlight>
</lang>
 
=={{header|Raku}}==
(formerly Perl 6)
Line 3,405 ⟶ 3,519:
<div style="display:inline-block">{{trans|Python}}</div> (or at least started out that way)
{{works with|Rakudo|2016.07}}
<syntaxhighlight lang="raku" perl6line>react {
my %connections;
Line 3,447 ⟶ 3,561:
}
}
}</langsyntaxhighlight>
 
Notes:
Line 3,453 ⟶ 3,567:
* It accepts messages encoded in UTF-8.
* It tokenizes the message streams at newline boundaries (using the <tt>Supply.lines</tt> method), which I think makes the most sense for a chat application.
 
=={{header|Ruby}}==
<langsyntaxhighlight Rubylang="ruby">require 'gserver'
 
class ChatServer < GServer
Line 3,523 ⟶ 3,636:
#Turn on informational messages
ChatServer.new(7000, '0.0.0.0', 100, $stderr, true).start.join
</syntaxhighlight>
</lang>
 
=={{header|Rust}}==
<langsyntaxhighlight lang="rust">
use std::collections::HashMap;
use std::io;
Line 3,623 ⟶ 3,735:
chat_loop(&listener).unwrap();
}
</syntaxhighlight>
</lang>
 
=={{header|Tcl}}==
{{works with|Tcl|8.6}}
<langsyntaxhighlight lang="tcl">package require Tcl 8.6
 
# Write a message to everyone except the sender of the message
Line 3,687 ⟶ 3,798:
socket -server {coroutine c[incr count] chat} 4004
set ::cmap {}; # Dictionary mapping nicks to channels
vwait forever; # Run event loop</langsyntaxhighlight>
 
=={{header|Visual Basic .NET}}==
{{trans|C#}}
<lang vbnet>Imports System.Net.Sockets
Imports System.Text
Imports System.Threading
 
Module Module1
 
Class State
Private ReadOnly client As TcpClient
Private ReadOnly sb As New StringBuilder
 
Public Sub New(name As String, client As TcpClient)
Me.Name = name
Me.client = client
End Sub
 
Public ReadOnly Property Name As String
 
Public Sub Send(text As String)
Dim bytes = Encoding.ASCII.GetBytes(String.Format("{0}" & vbCrLf, text))
client.GetStream().Write(bytes, 0, bytes.Length)
End Sub
End Class
 
ReadOnly connections As New Dictionary(Of Integer, State)
Dim listen As TcpListener
Dim serverThread As Thread
 
Sub Main()
listen = New TcpListener(Net.IPAddress.Parse("127.0.0.1"), 4004)
serverThread = New Thread(New ThreadStart(AddressOf DoListen))
serverThread.Start()
End Sub
 
Private Sub DoListen()
listen.Start()
Console.WriteLine("Server: Started server")
 
Do
Console.Write("Server: Waiting...")
Dim client = listen.AcceptTcpClient()
Console.WriteLine(" Connected")
 
' New thread with client
Dim clientThread As New Thread(New ParameterizedThreadStart(AddressOf DoClient))
 
clientThread.Start(client)
Loop
End Sub
 
Private Sub DoClient(client As TcpClient)
Console.WriteLine("Client (Thread: {0}): Connected!", Thread.CurrentThread.ManagedThreadId)
Dim bytes = Encoding.ASCII.GetBytes("Enter name: ")
client.GetStream().Write(bytes, 0, bytes.Length)
 
Dim done As Boolean
Dim name As String
Do
If Not client.Connected Then
Console.WriteLine("Client (Thread: {0}): Terminated!", Thread.CurrentThread.ManagedThreadId)
client.Close()
Thread.CurrentThread.Abort() ' Kill thread
End If
 
name = Receive(client)
done = True
 
For Each cl In connections
Dim state = cl.Value
If state.Name = name Then
bytes = Encoding.ASCII.GetBytes("Name already registered. Please enter your name: ")
client.GetStream().Write(bytes, 0, bytes.Length)
done = False
End If
Next
Loop While Not done
 
connections.Add(Thread.CurrentThread.ManagedThreadId, New State(name, client))
Console.WriteLine(vbTab & "Total connections: {0}", connections.Count)
Broadcast(String.Format("+++ {0} arrived +++", name))
 
Do
Dim text = Receive(client)
If text = "/quit" Then
Broadcast(String.Format("Connection from {0} closed.", name))
connections.Remove(Thread.CurrentThread.ManagedThreadId)
Console.WriteLine(vbTab & "Total connections: {0}", connections.Count)
Exit Do
End If
 
If Not client.Connected Then
Exit Do
End If
 
Broadcast(String.Format("{0}> {1}", name, text))
Loop
 
Console.WriteLine("Client (Thread: {0}): Terminated!", Thread.CurrentThread.ManagedThreadId)
client.Close()
Thread.CurrentThread.Abort()
End Sub
 
Private Function Receive(client As TcpClient) As String
Dim sb As New StringBuilder
Do
If client.Available > 0 Then
While client.Available > 0
Dim ch = Chr(client.GetStream.ReadByte())
If ch = vbCr Then
' ignore
Continue While
End If
If ch = vbLf Then
Return sb.ToString()
End If
sb.Append(ch)
End While
 
' pause
Thread.Sleep(100)
End If
Loop
End Function
 
Private Sub Broadcast(text As String)
Console.WriteLine(text)
For Each client In connections
If client.Key <> Thread.CurrentThread.ManagedThreadId Then
Dim state = client.Value
state.Send(text)
End If
Next
End Sub
 
End Module</lang>
 
=={{header|Wren}}==
Line 3,832 ⟶ 3,806:
 
As Wren's VM is single threaded we create separate VMs to service each potential client connection (limited to 10) which run in their own thread. As the only way for the VMs to share mutable state is to use global variables within the host, synchronization is needed when accessing such variables.
<langsyntaxhighlight ecmascriptlang="wren">/* chat_serverChat_server.wren */
 
class Clients {
Line 4,030 ⟶ 4,004:
foreign static read(connfd, count)
foreign static close(connfd)
}</langsyntaxhighlight>
<br>
We now embed this in the following C program, build and run it to start the server. To end the server, just press control-C. For testing purposes, clients can use telnet from separate terminals to connect to the server on port 5000.
<langsyntaxhighlight lang="c">/* gcc chat_serverChat_server.c -o chat_serverChat_server -lpthread -lwren -lm */
 
#include <sys/socket.h>
Line 4,313 ⟶ 4,287:
config.bindForeignMethodFn = &bindForeignMethod;
const char* module = "main";
const char* fileName = "chat_serverChat_server.wren";
script = readFile(fileName);
 
Line 4,385 ⟶ 4,359:
 
return 0;
}</langsyntaxhighlight>
 
=={{header|zkl}}==
{{trans|Python}}
On my Linux box, telnet seems to only want to connect to port 23.
<langsyntaxhighlight lang="zkl">const PORT=23;
var users=Dictionary(); // ( handle:socket, ...)
Line 4,438 ⟶ 4,412:
server:=Network.TCPServerSocket.open(PORT);
println("Listening on %s:%s".fmt(server.hostname,server.port));
server.listen(pipe); // Main event loop </langsyntaxhighlight>
{{out}}
Start the server:
Line 4,481 ⟶ 4,455:
Connection closed by foreign host.
</pre>
 
{{omit from|AutoHotkey}}
{{omit from|Lilypond}}
{{omit from|ML/I}}
{{omit from|Mathematica}}
{{omit from|Maxima}}
{{omit from|ML/I}}
{{omit from|PARI/GP|No good way to access network}}
{{omit from|Retro}}
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