event bus listener component enhacements

amqp_synch_call.py

@@ -170,5 +170,3 @@ if __name__ == '__main__':
 
     # r = amqp_request(connection, m, 'someImaginaryComponent')
     # print(repr(r))
-
-

event_bus_utils.py

 import os
 import pika
+import logging
 import threading
 
 # for using it as library and as a __main__
@@ -15,25 +16,23 @@ AMQP_EXCHANGE = 'amq.topic'
 class AmqpSynchCallTimeoutError(Exception):
     pass
 
+
 class AmqpListener(threading.Thread):
     COMPONENT_ID = 'amqp_listener_%s' % uuid.uuid1()
+    DEFAULT_TOPIC_SUSBCRIPTIONS = ['#']
     DEFAULT_EXCHAGE = 'amq.topic'
 
-    def __init__(self, amqp_url, amqp_exchange, topics, callback):
+    def __init__(self, amqp_url, amqp_exchange, callback, topics=None):
 
         threading.Thread.__init__(self)
 
         if callback is None:
-            self.message_dipatcher = print
+            self.message_dispatcher = print
         else:
-            self.message_dipatcher = callback
+            self.message_dispatcher = callback
 
-        try:
-            self.connection = pika.BlockingConnection(pika.URLParameters(amqp_url))
-            self.channel = self.connection.channel()
-        except pika.exceptions.ProbableAccessDeniedError:
-            self.message_dipatcher('Probable access denied error. Is provided AMQP_URL correct?')
-            self.exit()
+        self.connection = pika.BlockingConnection(pika.URLParameters(amqp_url))
+        self.channel = self.connection.channel()
 
         if amqp_exchange:
             self.exchange = amqp_exchange
@@ -47,15 +46,15 @@ class AmqpListener(threading.Thread):
                                    arguments={'x-max-length': 200})
 
         if topics:  # subscribe only to passed list
-            for t in topics:
-                self.channel.queue_bind(exchange=self.exchange,
-                                        queue=self.services_queue_name,
-                                        routing_key=t)
+            self.topics = topics
+        else:
+            self.topics = self.DEFAULT_EXCHAGE
 
-        else:  # subscribe to all events
+        for t in self.topics:
             self.channel.queue_bind(exchange=self.exchange,
                                     queue=self.services_queue_name,
-                                    routing_key='#')
+                                    routing_key=t)
+
         # Hello world message
         m = MsgTestingToolComponentReady(
             component=self.COMPONENT_ID,
@@ -98,29 +97,28 @@ class AmqpListener(threading.Thread):
             m = Message.from_json(body)
             m.update_properties(**props_dict)
             m.routing_key = method.routing_key
-            self.message_dipatcher(m)
+            self.message_dispatcher(m)
 
         except NonCompliantMessageFormatError as e:
-            self.message_dipatcher('%s got a non compliant message error %s' % (self.__class__.__name__, e))
+            logging.error('%s got a non compliant message error %s' % (self.__class__.__name__, e))
 
         except Exception as e:
-            pass
-            # self.message_dipatcher('Error : %s' % str(e))
-            # self.message_dipatcher(str(body))
+            logging.error(e)
 
         finally:
             ch.basic_ack(delivery_tag=method.delivery_tag)
 
     def run(self):
-        self.message_dipatcher("Starting thread listening on the event bus..")
+        logging.info("Starting thread listening on the event bus on topics %s" % self.topics)
         for i in range(1, 4):
             try:
                 self.channel.start_consuming()
             except pika.exceptions.ConnectionClosed as err:
-                self.message_dipatcher(err)
-                self.message_dipatcher('Unexpected connection closed, retrying %s/%s' % (i, 4))
+                logging.error('Unexpected connection closed, retrying %s/%s' % (i, 4))
+                logging.error(err)
+
+        logging.info('Bye byes!')
 
-        self.message_dipatcher('Bye byes!')
 
 def publish_message(connection, message):
     """
@@ -238,12 +236,14 @@ if __name__ == '__main__':
     def callback_function(message_received):
         print("Callback function received: \n\t" + repr(message_received))
 
+
     # amqp listener example:
     amqp_listener_thread = AmqpListener(
         amqp_url=AMQP_URL,
         amqp_exchange=AMQP_EXCHANGE,
-        topics='#',
-        callback=callback_function)
+        callback=callback_function,
+        topics='#'
+    )
 
     try:
         amqp_listener_thread.start()
@@ -271,4 +271,3 @@ if __name__ == '__main__':
 
     except AmqpSynchCallTimeoutError as e:
         print("Nobody answered to our request :'(")
-