class Publisher(object):
def __init__(self, name="(publisher-only)"):
self.name = name
address = self._get_address()
try:
self.connection = Connection(address, whoiam=name)
self._log(syslog.LOG_DEBUG, "Stablished a connection with the notifier server (%s)." % esc(str(address)))
except:
self._log(syslog.LOG_ERR, "Error when creating a connection with the notifier server (%s): %s." % esc(str(address), traceback.format_exc()))
raise
self.connection.send_object(pack_message(message_type='introduce_myself', name=name))
self._safe_topics = set()
def publish(self, topic, data):
if topic not in self._safe_topics:
fail_if_topic_isnt_valid(topic, allow_empty=False)
self._safe_topics.add(topic)
#self._log(syslog.LOG_DEBUG, "Sending publication of an event with topic '%s'." % esc(topic))
self.connection.send_object(pack_message(message_type='publish', topic=topic, obj=data, dont_pack_object=False))
#self._log(syslog.LOG_DEBUG, "Publication of an event sent.")
def close(self, *args, **kargs):
self.connection.close()
def _get_address(self):
import os, ConfigParser
script_home = os.path.abspath(os.path.dirname(__file__))
parent = os.path.pardir
# TODO This shouldn't be hardcoded!
config_file = os.path.join(script_home, parent, parent, parent, "config", "publish_subscribe.cfg")
config = ConfigParser.SafeConfigParser(defaults={
'wait_on_address': "localhost",
'wait_on_port': "5555",
})
config.read([config_file])
if not config.has_section("notifier"):
config.add_section("notifier")
address = (config.get("notifier", 'wait_on_address'), config.getint("notifier", 'wait_on_port'))
return address
def __repr__(self):
return "Endpoint (%s)" % self.name
def _log(self, level, message): #TODO remove the "%" stuff over an unknow string (not local string)
header = "%s: " % esc(repr(self))
message = header + message
syslog.syslog(level, message)
return message
class _Endpoint(threading.Thread):
def __init__(self, socket, notifier, codename):
threading.Thread.__init__(self)
self.connection = Connection(socket)
self.is_finished = False
self.notifier = notifier
self.codename = codename
self.name = ""
self.start()
def _is_valid_message(self, message_type, message_body):
if not message_type in ("subscribe", "publish", "unsubscribe", "introduce_myself"):
return False
return True
def _process_message(self, message_type, message_body):
if message_type == "publish":
topic, raw_obj = unpack_message_body(message_type, message_body, dont_unpack_object=True)
self.notifier.distribute_event(topic, raw_obj)
elif message_type == "unsubscribe":
topic = unpack_message_body(message_type, message_body)
self.notifier.unsubscribe_me(topic, self)
elif message_type == "introduce_myself":
self.name = unpack_message_body(message_type, message_body)
self._log(syslog.LOG_NOTICE, "Introduced himself as '%s'." % esc(self.name))
elif message_type == "subscribe":
topic = unpack_message_body(message_type, message_body)
self.notifier.register_subscriber(topic, self)
else:
self._log(syslog.LOG_ERR, "Invalid message. Unknown type: '%s'." % esc(message_type))
raise Exception("Invalid message.")
def run(self):
try:
while not self.connection.end_of_the_communication:
message_type, message_body = self.connection.receive_object()
self._process_message(message_type, message_body)
self._log(syslog.LOG_NOTICE, "The connection was closed by the other point of the connection.")
except:
self._log(syslog.LOG_ERR, "An exception has occurred when receiving/processing the messages: %s." % esc(traceback.format_exc()))
finally:
self.is_finished = True
def send_event(self, topic, obj_raw):
try:
self.connection.send_object(pack_message(message_type="publish", topic=topic, obj=obj_raw, dont_pack_object=True))
except:
self._log(syslog.LOG_ERR, "An exception when sending a message to it: %s." % esc(traceback.format_exc()))
self.is_finished = True
def close(self):
self._log(syslog.LOG_NOTICE, "Closing the connection with the endpoint.")
self.is_finished = True
self.connection.close()
self._log(syslog.LOG_NOTICE, "Connection closed")
def __repr__(self):
return "%s%s%s" % (self.codename, ((" (%s)" % self.name) if self.name else ""), (" [dead]" if self.is_finished else ""))
def _log(self, level, message):
message = ("%s: " % esc(repr(self))) + message
syslog.syslog(level, message)
