Ruby Eventmachine

APR 2ND, 2011

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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#serverEventMachine::run {  EventMachine::start_server "0.0.0.0", port, ServerHandler}#clientEventMachine::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 rubyrequire '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!"  endendEventMachine::run {  EventMachine::start_server "127.0.0.1", 8081, EchoServer}

一个简单的http client

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#!/usr/bin/env rubyrequire '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  endendEventMachine::run {  EventMachine::connect "www.baidu.com", 80, HttpClient}

连接失败的例子:

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#!/usr/bin/env rubyrequire '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  endendEventMachine::run {  EventMachine::connect "api.jquery.com", 8088, Client}