ruby on netty

time_client.rb

# Purely experimental exercise in exploring ideas for a JRuby gem for Netty -- http://jboss.org/netty
# Based on TimeClient example in Netty docs
 
require "java"
require "netty"
require "unix_time"

TimeClient = TcpNioClient.new do |pipeline|
  
  pipeline.insert :frame_decoder do
    def decode(context, channel, buffer)
      UnixTime.new(buffer.read_integer) unless buffer.readable_bytes < 4
    end
  end
  
  pipeline.insert :handler do
    on_new_message do |context, event|
      puts event.message.inspect
      event.channel.close
    end
  end
  
end

TimeClient.connect :host => "localhost", :port => 8080

time_server.rb

# Purely experimental exercise in exploring ideas for a JRuby gem for Netty -- http://jboss.org/netty
# Based on TimeServer example in Netty docs

require "java"
require "netty"
require "unix_time"

# A custom Handler that extends ChannelHandlers::Simple a SimpleChannelHandler
# Tries to separate the handler's lifecycle from the independent handler actions
class TimeServerHandler < ChannelHandlers::Simple
  
  on_connect :write_unix_time
  on_open    :add_to_active_channels
  
  def write_unix_time(context, event)
    time  = UnixTime.new(java.lang.System.current_time_millis / 1000)
    write = event.channel.write(time)
    write.add_listener(:close) # sugar for add_listener(Channel::ChannelFutureListener::CLOSE)
  end
  
  # Maybe push this into Base, if possible -- could also capture other common actions
  def add_to_active_channels(context, event)
    TimeServer.active_channels << event.channel
  end
  
  # Hook for exception handling. Base implementation prints stack trace on standard error & closes channel
  def rescue_exception(exception, channel)
    MyLogger.error(exception)
    super
  end
  
end

# DSL for defining a pipeline factory, inspired by Rails routes.rb 
pipeline_factory = PipelineFactory.assemble do |pipeline|
  
  # Alternate #insert forms:
  #   pipeline.insert TimeEncoder.new  -- infers name from class
  pipeline.insert :encoder do 
    on_write_request do |context, event|
      buffer = Buffer.new(4).write_integer(event.message) # sugar for write_int(arg.to_i)   
      write(context, event.future, buffer) # what about doing this automatically if the method/block returns a Buffer?
    end
  end

  pipeline.insert :handler, TimeServerHandler.new
  
end

# Server class bootstrapping common combos of transport/IO Model, handling shutdown & active channels, joining event loop, etc.
# One could imagine similar classes for client side
# Alternate #initialize forms:
#   TcpNioServer.new(pipeline_factory, :port => 8080, :threads => 5, :shutdown => ["TERM"]) -- uses separately defined PipelineFactory above
TimeServer = TcpNioServer.new :port => 8080 do |pipeline|  # this form yields a PipelineFactory for inline assembly
  pipeline.insert :encoder do 
    on_write_request do |context, event|
      buffer = Buffer.new(4).write_integer(event.message) # sugar for write_int(arg.to_i)   
      write(context, event.future, buffer) # what about doing this automatically if the method/block returns a Buffer?
    end
  end

  pipeline.insert :handler, TimeServerHandler.new
end

puts "TimeServer running on #{TimeServer.port}"
TimeServer.join # just future.await_uninterruptibly

unix_time.rb

class UnixTime
  
  attr_reader :value
  
  def initialize(value)
    @value = value
  end

  def to_i
    @value
  end
    
  def inspect
    java.util.Date.new(@value * 1000).to_string
  end
  
end