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Ruby Eventmachine

eventmachine 是一个快速轻量的网络协议框架，有不少ruby应用基于它实现，如thin, ruby-amqp. eventmachine在不同os上自动选择最佳的底层网络通知机制，在linux上用epoll，freebsd上用kqueue.

eventmachine对网络事件进行封装，有事件发生时回调预设的handler module。

事件处理都需要放在EventMachine::run里，可以分server, client两种模式

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#server
EventMachine::run {
  EventMachine::start_server "0.0.0.0", port, ServerHandler
}
#client
EventMachine::run {
  EventMachine::connect remote_server, port, ClientHandler #client
}

在一个网络连接的生存周期中，可能发生的回调事件有：

  1. post_init　handler对象创建后，注意client模式时，即使连接还未建立也会被调用
  2. connection_completed　主动连接远端服务器，连接建立时
  3. receive_data　有数据可读时, 在这里需要处理协议细节
  4. unbind　连接关闭，主动关闭，对方关闭或网络错误

在handler上可以使用send_data发送数据.

最简单的echo server

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#!/usr/bin/env ruby

require 'rubygems'
require 'eventmachine'

module EchoServer
  def post_init
    puts "-- someone connected to the echo server!"
  end

  def receive_data data
    send_data ">>>you sent: #{data}"
    close_connection if data =~ /quit/i
  end

  def unbind
    puts "-- someone disconnected from the echo server!"
  end
end

EventMachine::run {
  EventMachine::start_server "127.0.0.1", 8081, EchoServer
}

一个简单的http client

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#!/usr/bin/env ruby

require 'rubygems'
require 'eventmachine'

module HttpClient
  def post_init
    puts "sending request to server"
    send_data "GET / HTTP/1.1\r\nHost: www.baidu.com\r\nConnection: close\r\n\r\n"
  end

  def receive_data data
    puts "recv: #{data}"
  end

  def unbind
    puts "connection closed"
    EventMachine::stop
  end
end

EventMachine::run {
  EventMachine::connect "www.baidu.com", 80, HttpClient
}

连接失败的例子:

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#!/usr/bin/env ruby

require 'rubygems'
require 'eventmachine'

module Client
  def connection_completed
    puts "connected"
  end

  def post_init
    puts "handler inited"
  end

  def receive_data data
    puts "recv: #{data}"
  end

  def unbind
    puts "connection closed"
    EventMachine::stop
  end
end

EventMachine::run {
  EventMachine::connect "api.jquery.com", 8088, Client
}

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