事件机websocket服务器:如何将周期性消息推送到客户端

Question

我想使用ruby语言gem-em-websocket：https://github.com/igrigorik/em-websocket在eventmachine上运行websocket服务器。

我成功地运行了echo服务器演示：

EM.run {
  EM::WebSocket.run(:host => "0.0.0.0", :port => 8080) do |ws|
    ws.onopen { |handshake|
      puts "WebSocket connection open"
      ws.send "Hello Client, you connected to #{handshake.path}"
    }
    ws.onclose { puts "Connection closed" }
    ws.onmessage { |msg|
      puts "Recieved message: #{msg}"
      ws.send "Pong: #{msg}"
    }
  end
}

现在我想开发一个演示，服务器可以通过websocket消息每隔n毫秒（随机值）将一些数据推送到连接的客户端。。。实际上类似于：

def periodic_push
    # random elapsed: from 100 milliseconds to 6 seconds
    msec_value =  (rand(100..6000) / 1000.0 )
    message = "time: #{Time.now} value: #{msec_value.to_s}"
    ws.send message
    puts message
    sleep (msec_value)
end

我知道我不能在EM循环中使用sleep（）系统调用，但我不知道如何在CCD_ 1中插入周期性事件；也许是EventMachine::PeriodicTimer？怎样

有人可以帮我做一个代码示例chunck吗？谢谢乔治

Answer 1

我自己找到了一个解决方案：在下面的代码中，服务器每500毫秒向客户端推送一条websocket消息。（PeriodicTimer.new（0.5））。

我现在的问题是，如何定期重置计时器，以每N毫秒发送一条消息，其中N是一个随机值。。。知道吗

require 'eventmachine'
require 'em-websocket'
require 'socket'
EM.run {
  EM::WebSocket.run(:host => "0.0.0.0", :port => 8080) do |ws|
    ws.onopen { |handshake|
      puts "WebSocket connection open"
      ws.send "Hello Client, you connected to: #{Socket.gethostname}. websocket server path: #{handshake.path}"

    timer = EventMachine::PeriodicTimer.new(0.5) do
      value =  (rand(100..6000) / 1000.0 )
      message = "time: #{Time.now} value: #{value.to_s}"
      ws.send message
      puts message
    end
    }
    ws.onclose { puts "Connection closed" }
    #ws.onmessage { |msg|
    #  puts "Received message: #{msg}"
    #  ws.send "Pong: #{msg}"
    #}
  end
}

Answer 2

我的逻辑是在尽可能短的持续时间内运行事件机，并为所需的随机值添加延迟。例如

'ws.onopen { |handshake|
  puts "WebSocket connection open"
  ws.send "Hello Client, you connected to: #{Socket.gethostname}. websocket server path: #{handshake.path}"

timer = EventMachine::PeriodicTimer.new(0.0) do #the delay is kept to minimum here
  value =  (rand(100..6000) / 1000.0 )
  message = "time: #{Time.now} value: #{value.to_s}"
  ws.send message
  puts message
 delay(2) #2 seconds delay or the dynamic delay you want
end
}`

上下文：自行尝试