class Connector(object):
"""The Connector
See module description for more context.
"""
REQUIRED_KEYS = {"name", "mapping", "message"}
RECEIVER_NAME = "bm-connector"
def __init__(self, config=None):
"""Initialise the Connector and starts to listen to incoming messages.
:param config: Configuration to use (default config if None).
"""
self.log = logging.getLogger(self.__class__.__name__)
if config is None:
config = ConnConfig()
self.log.info("Falling back to default configuration.")
# errors up to here are allowed to terminate the program
mappings = self._read_mappings(config.mappings)
self.mapper = Mapper(mappings)
self.log.debug("Mappings read.")
self.sender = Sender(config.send.address, config.send.port,
config.broker.endpoint_prefix +
config.connector_id,
config.broker.topic,
config.connector_id)
self.log.info("Sender created.")
self.receiver = Receiver(self.RECEIVER_NAME,
config.listen.address, config.listen.port)
self.log.info("Receiver created.")
self.receiver.listen("/", self.handle_receive)
def _read_mappings(self, location):
"""Read the mappings into a list of dictionaries."""
# os/fs errors here are allowed to terminate the program
# yaml parse errors should not crash but log
mappings = []
for root, _, files in walk(location):
for f in files:
filepath = os.path.join(root, f)
with open(filepath, "r") as fd:
# TODO extract the below block?
try:
mp = yaml.load(fd)
for i in self.REQUIRED_KEYS:
if i not in mp:
raise LookupError(i)
mappings.append(mp)
except LookupError as e:
self.log.error(
"Missing key '{}' in file '{}'. Ignoring."
.format(e.args[0], filepath))
except Exception:
# TODO find correct exception types.
self.log.error(
"Failed to read mapping in '{}'. Ignoring."
.format(filepath))
return mappings
def handle_receive(self, message):
"""Handle message via mapping.
:param message: The message to map and send. (json)
"""
mapped = self.mapper.transform(message)
if mapped:
self.log.info("Mapped message is '{}'.".format(mapped))
self.sender.send(mapped)
def launch_receiver(coder):
receiver = Receiver(coder=coder)
receiver.listen()
