simple_chat_server.rb

# Please note that I adapted this code from an ancient (5 year old) article on IBM's site.
# I Forget the URL...
require "socket"
class ChatServer 
  def initialize( port ) 
    @sockets = []
    @port = port
  end # initialize 
  
  def run 
    if @this_thread then false
    else
      @server_socket = TCPServer.new( "", @port ) 
      @server_socket.setsockopt( Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1 ) 
      printf("Chatserver started on port %d\n", @port)
      @sockets.push( @server_socket )
      
      @this_thread = Thread.new(@server_socket, @sockets) { |server_socket, sockets|
        while true
          res = select( sockets, nil, nil, 0 )
          if res
            # Iterate through the tagged read descriptors
            res[0].each do |sock|
              # Received a connect to the server (listening) socket
              if sock == server_socket
                accept_new_connection 
              else 
                # Received something on a client socket 
                if sock.eof?
                  str = sprintf("Client left %s:%s\n", sock.peeraddr[2], sock.peeraddr[1])
                  broadcast_string( str, sock ) 
                  sock.close 
                  sockets.delete(sock) 
                else 
                  str = sprintf("[%s|%s]: %s",  sock.peeraddr[2], sock.peeraddr[1], sock.gets()) 
                  broadcast_string( str, sock ) 
                end#if
              end#if
            end#each 
          end#if
        end#while
      }
      @this_thread.run
      true
    end#if
  end#def

  def stop
    @this_thread.kill if @this_thread
    @sockets.each { |socket| socket.close }
    @sockets = []
    @this_thread = nil
  end
  
  private
  
    def broadcast_string( str, omit_sock )
      puts str
      @sockets.each { |client_sock|  client_sock.puts(str)  unless client_sock == @server_socket || client_sock == omit_sock } 
    end 
    
    def accept_new_connection
      new_sock = @server_socket.accept
      @sockets.push new_sock
      new_sock.puts("You're connected to the Ruby chatserver")
      str = sprintf("Client joined %s:%s", new_sock.peeraddr[2], new_sock.peeraddr[1])
      broadcast_string( str, new_sock ) 
    end # accept_new_connection 
  
end #server