CDE

Task/Chat-server/JavaScript/chat-server.js

@@ -0,0 +1,158 @@
+var net = require("net");
+var sys = require("sys");
+var EventEmitter = require("events").EventEmitter;
+
+/*******************************************************************************
+ * ChatServer
+ *
+ * Manages connections, users, and chat messages.
+ ******************************************************************************/
+
+function ChatServer() {
+  this.chatters = {};
+  this.server   = net.createServer(this.handleConnection.bind(this));
+  this.server.listen(1212, "localhost");
+}
+
+ChatServer.prototype.isNicknameLegal = function(nickname) {
+  // A nickname may contain letters or numbers only,
+  // and may only be used once.
+  if(nickname.replace(/[A-Za-z0-9]*/, '') != "") {
+    return false
+  }
+  for(used_nick in this.chatters) {
+    if(used_nick == nickname) {
+      return false;
+    }
+  }
+  return true;
+};
+
+ChatServer.prototype.handleConnection = function(connection) {
+  console.log("Incoming connection from " + connection.remoteAddress);
+  connection.setEncoding("utf8");
+
+  var chatter = new Chatter(connection, this);
+  chatter.on("chat", this.handleChat.bind(this));
+  chatter.on("join", this.handleJoin.bind(this));
+  chatter.on("leave", this.handleLeave.bind(this));
+};
+
+ChatServer.prototype.handleChat = function(chatter, message) {
+  this.sendToEveryChatterExcept(chatter, chatter.nickname + ": " + message);
+};
+
+ChatServer.prototype.handleJoin = function(chatter) {
+  console.log(chatter.nickname + " has joined the chat.");
+  this.sendToEveryChatter(chatter.nickname + " has joined the chat.");
+  this.addChatter(chatter);
+};
+
+ChatServer.prototype.handleLeave = function(chatter) {
+  console.log(chatter.nickname + " has left the chat.");
+  this.removeChatter(chatter);
+  this.sendToEveryChatter(chatter.nickname + " has left the chat.");
+};
+
+ChatServer.prototype.addChatter = function(chatter) {
+  this.chatters[chatter.nickname] = chatter;
+};
+
+ChatServer.prototype.removeChatter = function(chatter) {
+  delete this.chatters[chatter.nickname];
+};
+
+ChatServer.prototype.sendToEveryChatter = function(data) {
+  for(nickname in this.chatters) {
+    this.chatters[nickname].send(data);
+  }
+};
+
+ChatServer.prototype.sendToEveryChatterExcept = function(chatter, data) {
+  for(nickname in this.chatters) {
+    if(nickname != chatter.nickname) {
+      this.chatters[nickname].send(data);
+    }
+  }
+};
+
+/*******************************************************************************
+ * Chatter
+ *
+ * Represents a single user/connection in the chat server.
+ ******************************************************************************/
+
+function Chatter(socket, server) {
+  EventEmitter.call(this);
+
+  this.socket     = socket;
+  this.server     = server;
+  this.nickname   = "";
+  this.lineBuffer = new SocketLineBuffer(socket);
+
+  this.lineBuffer.on("line", this.handleNickname.bind(this));
+  this.socket.on("close", this.handleDisconnect.bind(this));
+
+  this.send("Welcome! What is your nickname?");
+};
+
+sys.inherits(Chatter, EventEmitter);
+
+Chatter.prototype.handleNickname = function(nickname) {
+  if(server.isNicknameLegal(nickname)) {
+    this.nickname = nickname;
+    this.lineBuffer.removeAllListeners("line");
+    this.lineBuffer.on("line", this.handleChat.bind(this));
+    this.send("Welcome to the chat, " + nickname + "!");
+    this.emit("join", this);
+  } else {
+    this.send("Sorry, but that nickname is not legal or is already in use!");
+    this.send("What is your nickname?");
+  }
+};
+
+Chatter.prototype.handleChat = function(line) {
+  this.emit("chat", this, line);
+};
+
+Chatter.prototype.handleDisconnect = function() {
+  this.emit("leave", this);
+};
+
+Chatter.prototype.send = function(data) {
+  this.socket.write(data + "\r\n");
+};
+
+/*******************************************************************************
+ * SocketLineBuffer
+ *
+ * Listens for and buffers incoming data on a socket and emits a 'line' event
+ * whenever a complete line is detected.
+ ******************************************************************************/
+
+function SocketLineBuffer(socket) {
+  EventEmitter.call(this);
+
+  this.socket = socket;
+  this.buffer = "";
+
+  this.socket.on("data", this.handleData.bind(this));
+};
+
+sys.inherits(SocketLineBuffer, EventEmitter);
+
+SocketLineBuffer.prototype.handleData = function(data) {
+  for(var i = 0; i < data.length; i++) {
+    var char = data.charAt(i);
+    this.buffer += char;
+    if(char == "\n") {
+      this.buffer = this.buffer.replace("\r\n", "");
+      this.buffer = this.buffer.replace("\n", "");
+      this.emit("line", this.buffer);
+      this.buffer = "";
+    }
+  }
+};
+
+// Start the server!
+server = new ChatServer();