step 2.3: multiple topics

pubsub/pub_server.py

@@ -1,6 +1,7 @@
 import zmq
 import sys
 import time
+import random
 
 port = "5556"
 if len(sys.argv) > 1:
@@ -15,12 +16,17 @@ socket = context.socket(zmq.PUB)
 # We can now send messages
 socket.bind(f"tcp://*:{port}")
 
-topic = "TIME"
+topics = ('TIME', 'RANDOM')
+messages = {}
 while True:
     # Time to publish the latest time!
-    messagedata = time.ctime()
+    messages['TIME'] = time.ctime()
+    messages['RANDOM'] = random.randint(1,10)
     # Note the use of XXX_string here;
     # the non-_stringy methods only work with bytes.
-    socket.send_string(f"{topic};{messagedata}")
-    print(f"Published topic {topic}: {messagedata}")
+    for topic in topics:
+        message = messages.get(topic, '')
+        if not message: continue
+        socket.send_string(f"{topic};{message}")
+        print(f"Published topic {topic}: {message}")
     time.sleep(1)

pubsub/sub_client.py

@@ -15,8 +15,9 @@ print(f"Collecting updates from time server at tcp://localhost:{port}")
 socket.connect(f"tcp://{ip}:{port}")
 
 # Filter by topic
-topicfilter = "TIME"
-socket.setsockopt_string(zmq.SUBSCRIBE, topicfilter)
+topicfilters = ("TIME", "RANDOM")
+socket.setsockopt_string(zmq.SUBSCRIBE, topicfilters[0])
+socket.setsockopt_string(zmq.SUBSCRIBE, topicfilters[1])
 
 # Process 5 updates
 topic_list = []