Simple client

client.rb

require 'socket'

@functions = {
    :ADD => lambda {|a, b| a + b},
    :SUBTRACT => lambda {|a, b| a - b},
    :MULTIPLY => lambda {|a, b| a * b}
}   

def build_response(msg)
    m = msg.split(':')
    func = m[0]
    uid = m[1]
    args = m[2..-1].map {|e| e.to_i}
    result = args.reduce(&@functions[func.to_sym])
    return "#{uid}:#{result}"
end 
    
def main
    s = UDPSocket.new
    s.bind('localhost', 9000)
    while true do
        msg = s.recv(4096)
        break if msg == '__SHUTDOWN__'
        s.send(build_response(msg), 0, 'localhost', 9001)
    end 
end         
        
main