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Python consumer that works with MassTransit
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import sys | |
import pika | |
import json | |
import re | |
import logging | |
import logging.handlers | |
PUBLISHER_EXCHANGE_NAME = 'DoSomeJob' | |
CONSUMER_QUEUE_NAME = 'python_consumer_queue' | |
# Logging config | |
logging.basicConfig( | |
level=logging.DEBUG, | |
format="%(asctime)s [%(threadName)-12.12s] [%(levelname)-5.5s] %(message)s", | |
handlers=[ | |
logging.StreamHandler(sys.stdout) | |
]) | |
logger = logging.getLogger() | |
def callback(ch, method, props, body): | |
logging.info("Message received - CorrelationId={1}".format(props.correlation_id)) | |
logging.debug("Message contents:\n'{0}'".format(body)) | |
try: | |
request = json.loads(body.decode('UTF-8')) | |
# Do some stuff | |
result = 'some string result... It could be an object' | |
exchange = getExchangeName(request['responseAddress']) | |
logging.debug("Exchange extracted from responseAddress request: '{0}'".format(exchange)) | |
responseBody = createMassTransitResponse(result, request) | |
logging.debug("Response body for MassTransit:\n'{0}'".format(responseBody)) | |
# Respond to the initiator exchange extracted from request['responseAddress'] | |
ch.basic_publish(exchange, | |
routing_key = exchange, | |
properties = pika.BasicProperties(correlation_id = props.correlation_id), | |
body = responseBody) | |
except Exception as e: | |
logging.error("error {0}".format(e)) | |
logging.error(traceback.format_exc()) | |
ch.basic_ack(delivery_tag = method.delivery_tag) | |
logging.info("Message handling complete") | |
#It just extract the exchange name from a URI | |
def getExchangeName(address): | |
parts = re.search('/(\w+)\?', address) | |
return parts.group(1) | |
# It creates a message according to the Masstransit requirements. More info http://masstransit-project.com/MassTransit/advanced/interoperability.html | |
def createMassTransitResponse(result, requestBody): | |
response = { | |
'requestId': requestBody['requestId'], | |
'correlationId': requestBody['correlationId'], | |
'conversationId': requestBody['conversationId'], | |
'initiatorId': requestBody['correlationId'], | |
'sourceAddress': requestBody['destinationAddress'], | |
'destinationAddress': requestBody['sourceAddress'], | |
'messageType': [ | |
'urn:message:INTERFACE_NAMESPACE_HERE:YOUR_CSHARP_INTERFACE_NAME' | |
], | |
# The `message` value/object must implement the interface mentioned on messageType | |
'message': result | |
} | |
return json.dumps(response) | |
connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost')) | |
channel = connection.channel() | |
#Make sure that we have an Exchange created the same way as masstransit creates one | |
channel.exchange_declare(exchange=PUBLISHER_EXCHANGE_NAME, exchange_type='fanout', durable=True) | |
channel.queue_declare(queue=CONSUMER_QUEUE_NAME, | |
exclusive=False, | |
auto_delete=True, | |
durable=False) | |
channel.queue_bind(queue=CONSUMER_QUEUE_NAME, exchange=PUBLISHER_EXCHANGE_NAME) | |
channel.basic_consume(callback, queue=CONSUMER_QUEUE_NAME) | |
channel.start_consuming() |
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I'm glad it helped you. That was my first attempt make a python script getting messages from a MassTransit based app. I'm not a python expert BTW...