gevent

gevent/Event

• Source Code

  import gevent
  from gevent.pywsgi import WSGIServer
  from gevent.queue import Queue, Empty
  
  data_source = Queue()
  
  def producer():
      while True:
          data_source.put_nowait('Hello World')
          gevent.sleep(1)
  
  def ajax_endpoint(environ, start_response):
      status = '200 OK'
      headers = [
          ('Content-Type', 'application/json')
      ]
  
      start_response(status, headers)
  
      while True:
          try:
              datum = data_source.get(timeout=5)
              yield datum + '\n'
          except Empty:
              pass
  
  gevent.spawn(producer)
  
  WSGIServer(('', 8000), ajax_endpoint).serve_forever()
  

• Streaming tells clinet not close by adding Transfer Encoding: chunked in Response Headers

gevent + Django

• Impossible if directly realize in Django
• Django is request and resposne
• Should start a extra service

References

[1] TIMEX@StackOverflow, Does Django have a way to open a HTTP long poll connection?

[2] DeveloperWorks@IBM, Reverse Ajax, Part 1: Introduction to Comet