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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8 | #server
EventMachine::run {
EventMachine::start_server "0.0.0.0", port, ServerHandler
}
#client
EventMachine::run {
EventMachine::connect remote_server, port, ClientHandler #client
}
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在一个网络连接的生存周期中，可能发生的回调事件有：
- 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
- connection_completed 主动连接远端服务器，连接建立时
- receive_data 有数据可读时, 在这里需要处理协议细节
- 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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23 | #!/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
}
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一个简单的http client
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24 | #!/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
}
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连接失败的例子:
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27 | #!/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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