class SSEResource(resource.Resource):
"""
Twisted web resource that will work as the SSE server.
"""
isLeaf = True
def __init__(self):
"""
@prop subscribers are the requests which should be updated
when new information is published to the sse_resource.
"""
self.subscribers = set()
# The device ids who have sent a message through this sse resource
self.ids = []
fp = open(settings["data_schema"], "r")
self.data_schema_manager = DataSchemaManager(fp)
self.data_schema_manager.register_inotify_callback(self.schema_changed)
fp = open(settings["layout"], "r")
self.layout_manager = LayoutManager(fp, self.data_schema_manager)
self.layout_manager.register_inotify_callback(self.layout_changed)
self.layout_manager.compile()
if settings['activate_mongo']:
self.mongo_client = MongoClient(settings['mongo_host'])
self.db = self.mongo_client[settings['mongo_db']]
reactor.addSystemEventTrigger('after', 'shutdown', self.clean_up)
def clean_up(self):
log.msg("SSEResource cleanup.")
self.data_schema_manager.fp.close()
self.layout_manager.fp.close()
def removeSubscriber(self, subscriber):
"""
When the request is finished for some reason, the request is
finished and the subscriber is removed from the set.
"""
if subscriber in self.subscribers:
subscriber.finish()
self.subscribers.remove(subscriber)
def render_GET(self, request):
"""
Called when twisted wants to render the page, this method is
asynchronous and therefore returns NOT_DONE_YET.
"""
def wrap(x):
return '"' + str(x) + '"'
request.setHeader('Content-Type', 'text/event-stream; charset=utf-8')
request.setResponseCode(200)
self.subscribers.add(request)
d = request.notifyFinish()
d.addBoth(self.removeSubscriber)
msg = []
if len(self.ids) > 0:
msg.append('event: new_devices\n')
msg.append('data: [%s]\n\n' % ",".join(map(wrap, self.ids)))
request.write("".join(msg))
msg = []
widgets = self.layout_manager.get_widgets()
msg.append('event: new_widgets\n')
msg.append('data: %s\n\n' % widgets)
request.write("".join(msg))
msg = []
events = self.data_schema_manager.get_events()
jdata = json.dumps({'added': events, 'removed': []})
msg.append('event: new_event_sources\n')
msg.append('data: %s\n\n' % jdata)
request.write("".join(msg))
log.msg("SSE connection made by %s" % request.getClientIP())
return server.NOT_DONE_YET
def publish(self, data):
"""
When data arrives it is written to every request which is in the
subscribers set.
"""
if self.data_schema_manager.validate(data):
jdata = json.loads(data)
iid = jdata["id"]
iid_encoded = iid.encode('ascii', 'ignore')
if settings["activate_mongo"]:
self.store(data)
msg = []
if iid not in self.ids:
log.msg("New connection from device %s" % iid)
self.ids.append(iid)
msg.append('event: new_devices\n')
msg.append('data: ["%s"]\n\n' % iid_encoded)
for event, data in jdata.items():
if event in ["id"]:
continue
event_name = event.encode('ascii', 'ignore')
msg.append("event: id%s-%s\n" % (iid_encoded, event_name))
msg.append("data: %s\n\n" % json.dumps(data))
for subscriber in self.subscribers:
subscriber.write("".join(msg))
def store(self, data):
"""
Store the data in the data collection.
A string is passed as attribute to avoid pollution of the argument.
"""
jdata = json.loads(data)
jdata['timestamp'] = datetime.utcnow()
self.db.data.insert(jdata)
def broadcast(self, event_source, data):
msg = []
jdata = json.dumps(data)
msg.append('event: %s\n' % event_source)
msg.append('data: %s\n\n' % jdata)
for subscriber in self.subscribers:
subscriber.write("".join(msg))
def layout_changed(self, data):
self.broadcast('new_widgets', data)
def schema_changed(self, data):
self.broadcast('new_event_sources', data)
