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296
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1 """
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2 requesting /graph/foo returns an SSE patch stream that's the
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3 result of fetching multiple other SSE patch streams. The result stream
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4 may include new statements injected by this service.
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5
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6 Future:
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7 - filter out unneeded stmts from the sources
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8 - give a time resolution and concatenate patches faster than that res
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9 """
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10
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11 config = {
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12 'streams': [
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13 {'id': 'home',
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14 'sources': [
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15 #'http://bang:9059/graph/events',
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16 'http://plus:9075/graph/events',
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17 ]
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18 },
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19 ]
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20 }
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21
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22 from crochet import no_setup
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23 no_setup()
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24
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25 import sys, logging, weakref, traceback, json
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26 from twisted.internet import reactor
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27 import cyclone.web, cyclone.sse
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28 from rdflib import ConjunctiveGraph
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29 from rdflib.parser import StringInputSource
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30 from docopt import docopt
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31
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32 from twisted_sse_demo.eventsource import EventSource
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33
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34 sys.path.append("../../lib")
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35 from logsetup import log
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36 from patchablegraph import patchAsJson
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37
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38 sys.path.append("/my/proj/light9")
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39 from light9.rdfdb.patch import Patch
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40
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41 def patchFromJson(j):
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42 body = json.loads(j)['patch']
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43 a = ConjunctiveGraph()
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44 a.parse(StringInputSource(json.dumps(body['adds'])), format='json-ld')
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45 d = ConjunctiveGraph()
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46 d.parse(StringInputSource(json.dumps(body['deletes'])), format='json-ld')
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47 return Patch(addGraph=a, delGraph=d)
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48
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49 class PatchSource(object):
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50 """wrap EventSource so it emits Patch objects and has an explicit stop method"""
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51 def __init__(self, url):
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52 self.url = url
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53 self._listeners = set()#weakref.WeakSet()
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54 log.info('start read from %s', url)
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55 self._eventSource = EventSource(url)
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56 self._eventSource.protocol.delimiter = '\n'
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57
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58 self._eventSource.addEventListener('fullGraph', self._onFullGraph)
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59 self._eventSource.addEventListener('patch', self._onMessage)
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60
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61 def _onFullGraph(self, message):
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62 try:
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63 g = ConjunctiveGraph()
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64 g.parse(StringInputSource(message), format='json-ld')
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65 p = Patch(addGraph=g)
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66 self._sendPatch(p)
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67 except:
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68 traceback.print_exc()
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69
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70 def _onMessage(self, message):
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71 try:
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72 p = patchFromJson(message)
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73 self._sendPatch(p)
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74 except:
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75 traceback.print_exc()
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76
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77 def _sendPatch(self, p):
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78 log.info('output patch to %s listeners', p, len(self._listeners))
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79 for lis in self._listeners:
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80 lis(p)
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81
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82 def addPatchListener(self, func):
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83 self._listeners.add(func)
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84
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85 def stop(self):
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86 log.info('stop read from %s', self.url)
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87 self._eventSource.protocol.stopProducing() #?
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88 self._eventSource = None
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89
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90 def __del__(self):
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91 if self._eventSource:
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92 raise ValueError
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93
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94 class GraphClient(object):
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95 """A listener of some EventSources that sends patches to one of our clients."""
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96
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97 def __init__(self, handler, patchSources):
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98 self.handler = handler
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99
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100 for ps in patchSources:
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101 ps.addPatchListener(self.onPatch)
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102
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103 def onPatch(self, p):
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104 self.handler.sendEvent(message=patchAsJson(p), event='patch')
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105
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106 class GraphClients(object):
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107 """All the active EventClient objects"""
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108 def __init__(self):
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109 self.clients = {} # url: EventClient
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110 self.listeners = {} # url: [GraphClient]
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111
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112 def addSseHandler(self, handler, streamId):
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113 log.info('addSseHandler %r %r', handler, streamId)
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114 matches = [s for s in config['streams'] if s['id'] == streamId]
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115 if len(matches) != 1:
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116 raise ValueError("%s matches for %r" % (len(matches), streamId))
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117 ecs = []
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118 for source in matches[0]['sources']:
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119 if source not in self.clients:
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120 self.clients[source] = PatchSource(source)
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121 ecs.append(self.clients[source])
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122
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123 self.listeners.setdefault(source, []).append(GraphClient(handler, ecs))
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124 print self.__dict__
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125
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126 def removeSseHandler(self, handler):
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127 log.info('removeSseHandler %r', handler)
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128 for url, graphClients in self.listeners.items():
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129 keep = []
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130 for gc in graphClients:
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131 if gc.handler != handler:
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132 keep.append(gc)
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133 graphClients[:] = keep
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134 if not keep:
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135 self.clients[url].stop()
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136 del self.clients[url]
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137 del self.listeners[url]
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138
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139 class SomeGraph(cyclone.sse.SSEHandler):
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140 def __init__(self, application, request):
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141 cyclone.sse.SSEHandler.__init__(self, application, request)
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142 self.id = request.uri[len('/graph/'):]
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143 self.graphClients = self.settings.graphClients
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144
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145 def bind(self):
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146 self.graphClients.addSseHandler(self, self.id)
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147
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148 def unbind(self):
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149 self.graphClients.removeSseHandler(self)
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150
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151 if __name__ == '__main__':
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152
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153 arg = docopt("""
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154 Usage: sse_collector.py [options]
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155
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156 -v Verbose
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157 """)
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158
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159 if arg['-v']:
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160 import twisted.python.log
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161 twisted.python.log.startLogging(sys.stdout)
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162 log.setLevel(logging.DEBUG)
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163
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164
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165 graphClients = GraphClients()
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166
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167 reactor.listenTCP(
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168 9071,
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169 cyclone.web.Application(
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170 handlers=[
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171 (r'/graph/(.*)', SomeGraph),
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172 ],
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173 graphClients=graphClients),
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174 interface='::')
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175 reactor.run()
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