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1 import sys
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2
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3 from twisted.web import server, resource
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4 from twisted.internet import reactor
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5 from twisted.python import log
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6
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7
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8 class Root(resource.Resource):
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9 """
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10 Root resource; serves JavaScript
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11 """
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12 def getChild(self, name, request):
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13 if name == '':
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14 return self
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15 return resource.Resource.getChild(self, name, request)
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16
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17 def render_GET(self, request):
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18 return r"""
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19 <html>
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20 <head>
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21 <script language="JavaScript">
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22 eventSource = new EventSource("http://localhost:12000/subscribe");
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23 eventSource.onmessage = function(event) {
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24 element = document.getElementById("event-data");
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25 element.innerHTML = event.data;
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26 };
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27 </script>
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28 </head>
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29 <body>
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30 <h1> Welcome to the SSE demo </h1>
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31 <h3> Event data: </h3>
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32 <p id="event-data"></p>
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33 </body>
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34 </html>
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35 """
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36
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37
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38 class Subscribe(resource.Resource):
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39 """
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40 Implements the subscribe resource
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41 """
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42 isLeaf = True
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43
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44 def __init__(self):
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45 self.subscribers = set()
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46
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47 def render_GET(self, request):
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48 request.setHeader('Content-Type', 'text/event-stream; charset=utf-8')
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49 request.setResponseCode(200)
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50 self.subscribers.add(request)
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51 d = request.notifyFinish()
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52 d.addBoth(self.removeSubscriber)
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53 log.msg("Adding subscriber...")
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54 request.write("")
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55 return server.NOT_DONE_YET
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56
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57 def publishToAll(self, data):
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58 for subscriber in self.subscribers:
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59 for line in data:
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60 subscriber.write("data: %s\r\n" % line)
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61 # NOTE: the last CRLF is required to dispatch the event at the client
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62 subscriber.write("\r\n")
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63
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64 def removeSubscriber(self, subscriber):
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65 if subscriber in self.subscribers:
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66 log.msg("Removing subscriber..")
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67 self.subscribers.remove(subscriber)
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68
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69
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70 class Publish(resource.Resource):
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71 """
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72 Implements the publish resource
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73 """
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74 isLeaf = True
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75
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76 def __init__(self, subscriber):
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77 self.subscriber = subscriber
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78
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79 def render_POST(self, request):
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80 if 'data' not in request.args:
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81 request.setResponseCode(400)
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82 return "The parameter 'data' must be set\n"
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83 data = request.args.get('data')
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84 self.subscriber.publishToAll(data)
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85 return 'Thank you for publishing data %s\n' % '\n'.join(data)
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86
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87
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88 root = Root()
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89 subscribe = Subscribe()
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90 root.putChild('subscribe', subscribe)
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91 root.putChild('publish', Publish(subscribe))
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92 site = server.Site(root)
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93 reactor.listenTCP(12000, site)
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94 log.startLogging(sys.stdout)
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95 reactor.run()
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