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WebSockets+Redis构建EventMachine
EventMachine 是一个Ruby的事件驱动网络库，本文不是要介绍它，而是要介绍一个以Redis 的 Pub/Sub 机制为后端，以WebSockets为前端的类EventMachine实现。
前端代码，创建Socket连接到本地8081端口，当有消息push过来的时候，将消息打印到指定的div里：- <!DOCTYPE html>
- <html>
- <head>
- <title>Websockets!</title>
- <script>
- function onMessage(evt) {
- con = document.getElementById("console");
- con.innerHTML += evt.data;
- con.innerHTML += '<br />';
- }
- websocket = new WebSocket("ws://localhost:8081");
- websocket.onmessage = function(evt) { onMessage(evt); };
- </script>
- </head>
- <body>
- <div id="console">
- </div>
- </body>
- </html>后端代码：
- require 'redis'
- require 'em-websocket'
- SOCKETS = []
- @redis = Redis.new(:host => '127.0.0.1', :post => 6379)
- # Creating a thread for the EM event loop
- Thread.new do
- EventMachine.run do
- # Creates a websocket listener
- EventMachine::WebSocket.start(:host => '0.0.0.0', :port => 8081) do |ws|
- ws.onopen do
- # When someone connects I want to add that socket to the SOCKETS array that
- # I instantiated above
- puts 'creating socket'
- SOCKETS << ws
- end
- ws.onclose do
- # Upon the close of the connection I remove it from my list of running sockets
- puts 'closing socket'
- SOCKETS.delete ws
- end
- end
- end
- end
- # Creating a thread for the redis subscribe block
- Thread.new do
- @redis.subscribe('ws') do |on|
- # When a message is published to 'ws'
- on.message do |chan, msg|
- puts "sending message: #{msg}"
- # Send out the message on each open socket
- SOCKETS.each {|s| s.send msg}
- end
- end
- end
当前后端都启动并连接上后，你就可以用如下代码往Redis的ws这个key上写消息，页面上就能看到push过来的消息了：- require 'redis'
- @redis = Redis.new(:host => '127.0.0.1', :post => 6379)
- @redis.publish 'ws', 'Something witty'
have fun！
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发表于 2012-02-16 19:14
