From: Justin Collins <collinsj@...>
Date: 2006-10-17T10:07:27+09:00
Subject: Re: A basic chat program

Jan Svitok wrote:
> On 10/17/06, Michael Hall <logarkh@gmail.com> wrote:
>> Okay I'm looking to make a basic chat program that I can connect to via
>> telnet for learning purposes.
>>
>> I want a user to connect then login in or be able to create a new user,
>> new users would be saved as files. then when they're in the program they
>> can talk on different channels by typing "channel1 <message>" or
>> "channel2 <message>" etc. Also I'd like to put the code in different
>> files i.e. connection/login/user create code in one file, the
>> channel/talk functions in another and in a third file a list of the
>> commands that can be typed pointing to the function name (like
>> {"<command", function_name} so that when they type the command that's
>> listed there it will find the correct function and run it) I need help
>> on how to go about this, psuedo code, code examples etc.
>
> Have a look at Socket::TCPServer in stdlib. That would be the base for
> your server.
>

You may also want to look at GServer[1] in the standard library, which 
is probably simpler to use. Putting this together with the Observer[2] 
class, it makes it fairly simple, as long as you are okay with handling 
threads and such. I'd recommend using YAML[3] for storing your users and 
their settings/passwords/etc.

For the basic idea, you might start off with something like this (simply 
echoes input to everyone):

require 'gserver'
require 'observer'

class MyServer < GServer
  include Observable

  def initialize(port = 5555, *args)
    super(port, *args)
  end

  def serve(io)
    user = User.new(io)
    self.add_observer(user)
    user.add_observer(self)
    user.run
  end

  def update(message)
    changed
    notify_observers(message)
  end
end

class User
  include Observable

  def initialize(io)
    @io = io
  end

  def update(message)
    @io.puts message
  end

  def run
    loop do
      input = @io.gets
      changed
      notify_observers(input)
    end
  end
end

MyServer.new.start.join


Just run that, and connect a couple of telnet sessions to port 5555. 
Type in a message and it should be echoed to everyone. Hooray!
Note that MyServer and User are both observing each other, so that the 
server can echo a message from any user to all the others (including the 
original sender). This simplifies having to worry about threads and 
queues and such.
I hope that will give you some ideas.

-Justin
 
[1]http://ruby-doc.org/stdlib/libdoc/gserver/rdoc/index.html
[2]http://ruby-doc.org/stdlib/libdoc/observer/rdoc/index.html
[3]http://yaml4r.sourceforge.net/doc/