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pythonhtmlfirefoxcherrypyserver-sent-events

Firefox doesn't restore server-sent events connection

Test case implemented with Python and CherryPy:

import cherrypy, time

class Root():

    @cherrypy.expose
    def index(self):
        return r'''<!DOCTYPE html>
<html>
 <head>
  <title>Server-sent events test</title>
  <style>html,body,#test{height:98%;}</style>
 </head>
 <body>
  <script type="text/javascript">
    document.addEventListener('DOMContentLoaded', function () {
      var source = new EventSource('gettime');
      source.addEventListener('time', function (event) {
        document.getElementById('test').innerHTML += event.data + "\n";
      });
      source.addEventListener('error', function (event){
        console.log('SSE error:', event);
        console.log('SSE state:', source.readyState);
      });
    }, false);
  </script>
  <textarea id="test"></textarea>
 </body>
</html>'''

    @cherrypy.expose
    def gettime(self):
        cherrypy.response.headers["Content-Type"] = "text/event-stream"
        def generator():
            while True:
                time.sleep(1)
                yield "event: time\n" + "data: " + str(time.time()) + "\n\n"
        return generator()
    gettime._cp_config = {'response.stream': True}

if __name__ == '__main__':
    cherrypy.config.update({'server.socket_host': '0.0.0.0'})
    cherrypy.quickstart(Root())

After receiving some messages successfully I manually drop the connection, then in Firefox' web console appears JS Error: The connection to http://localhost:8080/gettime was interrupted while the page was loading.

According to the spec, Clients will reconnect if the connection is closed, but Firefox doesn't. Error event handler reports that the source is in CLOSED state.

CLOSED (numeric value 2) The connection is not open, and the user agent is not trying to reconnect. Either there was a fatal error or the close() method was invoked.
So there was a fatal error?

  • In Chromium it works, error handler reports that the source is in CONNECTING (0) state (as it should) and connection is automatically restored within a few seconds
  • Have tried Firefox 26, Firefox 24 ESR and Iceweasel 17 on Linux and Windows platforms, all the same
  • Have checked raw protocol and headers, looks ok
  • Have tried to add retry: 3000 to each sent event
  • Have tried to move JavaScript out of event listener and wrapping it into setTimeout
Solution

  • The bug is fixed in Firefox 36.