import psycopg2
from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT
import eventlet
from eventlet import wsgi
from eventlet import websocket
from eventlet.hubs import trampoline
dsn = "dbname=test" # customise this
def dblisten(q):
"""
Open a db connection and add notifications to *q*.
"""
cnn = psycopg2.connect(dsn)
cnn.set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)
cur = cnn.cursor()
cur.execute("LISTEN data;")
while 1:
trampoline(cnn, read=True)
cnn.poll()
while cnn.notifies:
n = cnn.notifies.pop()
q.put(n)
@websocket.WebSocketWSGI
def handle(ws):
"""
Receive a connection and send it database notifications.
"""
q = eventlet.Queue()
eventlet.spawn(dblisten, q)
while 1:
n = q.get()
print n
ws.send(n.payload)
def dispatch(environ, start_response):
if environ['PATH_INFO'] == '/data':
return handle(environ, start_response)
else:
start_response('200 OK',
[('content-type', 'text/html')])
return [page]
page = """
pushdemo
"""
if __name__ == "__main__":
listener = eventlet.listen(('127.0.0.1', 7000))
wsgi.server(listener, dispatch)