Rest Gateway: Displaying received messages via rest

message-broker/rabbit-mq-test/consumer.py

@@ -2,14 +2,15 @@ import pika
 
 EXCHANGE_NAME = 'rest-gateway'
 EXCHANGE_TYPE = 'direct'
+ROUTING_KEY = 'rest-gateway'
 
 connection = pika.BlockingConnection(pika.ConnectionParameters('143.205.173.36', 30302, heartbeat=600, blocked_connection_timeout=300))
 channel = connection.channel()
 
 channel.exchange_declare(exchange=EXCHANGE_NAME, exchange_type=EXCHANGE_TYPE)
-result = channel.queue_declare(queue='rest-gateway', exclusive=True, auto_delete=True)
+result = channel.queue_declare(queue=ROUTING_KEY, exclusive=False, auto_delete=False)
 queue_name = result.method.queue
-channel.queue_bind(exchange=EXCHANGE_NAME, queue=queue_name, routing_key='rest-gateway')
+channel.queue_bind(exchange=EXCHANGE_NAME, queue=queue_name, routing_key=ROUTING_KEY)
 
 def callback(ch, method, properties, body):
     print(f"### Received: {body}")

rest-gateway/app/MessageList.py

+from __future__ import annotations
+
+class MessageList:
+    __instance = None
+    _messages = []
+
+    @staticmethod 
+    def getInstance() -> MessageList:
+        """ Static access method. """
+        if MessageList.__instance == None:
+            MessageList.__instance = MessageList()
+        return MessageList.__instance
+
+    def __init__(self):
+        """ Virtually private constructor. """
+        if MessageList.__instance != None:
+            raise Exception("This class is a singleton!")
+        else:
+            MessageList.__instance = self
+    
+    def appendMessage(self, message):
+        self._messages.append(message)
+
+    def getMessages(self):
+        return self._messages
\ No newline at end of file

rest-gateway/app/configs/swagger.yml

@@ -30,3 +30,13 @@ paths:
         200:
           description: "Successful echo of request data"
   
+  /messages:
+    get:
+      operationId: "debug.get_messages"
+      tags:
+        - "Received Messages"
+      summary: "List of all received messages"
+      description: "Lists all messages received from Rabbit MQ."
+      responses:
+        200:
+          description: "Message list"
\ No newline at end of file

rest-gateway/app/debug.py

+from MessageList import MessageList
 from flask import request
 
 def echo():
     return request.json
 
- 
+def get_messages():
\ No newline at end of file
+    messages = MessageList.getInstance().getMessages()
+    return str(messages)

rest-gateway/app/main.py

@@ -17,21 +17,22 @@ import connexion
 from multiprocessing import Process
 from messaging.MessageReceiver import MessageReceiver
 from messaging.MessageSender import MessageSender
+from MessageList import MessageList
 
 RABBIT_MQ_DNS_NAME = 'rabbit-mq'
 RABBIT_MQ_PORT = '5672'
 
-message_sender = None
+messages = MessageList.getInstance()
 
 # init message handler
 def message_received_callback(channel, method, properties, body):
+    messages.appendMessage(body)
     print(f"### Received: {body}")
 
 def pika_error_callback(error):
+    # TODO gracefully handle error
     print("Rabbit MQ error!")
-    global flask_server
-    flask_server.terminate()
-    sys.exit()
+    os._exit(1)
 
 # load swagger config 
 app = connexion.App(__name__, specification_dir='configs/')
@@ -41,9 +42,6 @@ app.add_api('swagger.yml')
 def api_root():
     return 'Endpoint of SMART RESTful API Gateway!'
 
-def run_flask():
-    app.run(host='0.0.0.0', port=5000, debug=True, use_reloader=False) # disable reloader so only subscribed once to rabbitmq
-
 # start app
 if __name__ == '__main__':
     message_rec = MessageReceiver(
@@ -51,8 +49,4 @@ if __name__ == '__main__':
         exchange_name='rest-gateway', exchange_type='direct', queue_name='rest-gateway', auto_ack=True)
     message_rec.start(message_received_callback, pika_error_callback)
 
-    global flask_server
-    flask_server = Process(target=run_flask)
+    app.run(host='0.0.0.0', port=5000, debug=True, use_reloader=False) # disable reloader so only subscribed once to rabbitmq
\ No newline at end of file
-    flask_server.start()
-
-    flask_server.join()
\ No newline at end of file