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https://issues.apache.org/jira/browse/AMQ-9592?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17896775#comment-17896775
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Ken Liao commented on AMQ-9592:
-------------------------------
I think the discrepancy lies in "For new client Id broker must create new
session, so messages sent after client 1 disconnected should route to client 1
only since client 2 because it was connected after those 5 messages were sent".
It was correctly delivered exactly once to the intended client like you said,
but it also delivered to unintended client at the same time.
Since clean_session=False, the behavior more or less maps to durable
subscription. In this case, new durable subscription, created after messages
intended for an older inactive durable subscription were received by the
broker, should not get those messages.
Nevertheless, let me try to find the committee of MQTTv3.1.1 and ask for
clarification.
> Incorrect MQTTv3.1.1 behaviour: QoS2 messages were delivered to unintended
> consumers
> -------------------------------------------------------------------------------------
>
> Key: AMQ-9592
> URL: https://issues.apache.org/jira/browse/AMQ-9592
> Project: ActiveMQ Classic
> Issue Type: Bug
> Components: MQTT
> Affects Versions: 5.18.5, 6.1.3
> Reporter: Ken Liao
> Assignee: Jean-Baptiste Onofré
> Priority: Major
> Fix For: 6.2.0, 5.18.7, 6.1.5
>
>
> To replicate:
> - Run a subscriber with QOS2 to a topic with client ID say "1"and stop it
> - Publish 5 messages to the topic, do not consume these yet.
> - Run another subscriber with QOS2 to the topic with a different client ID
> say "2'.
> - This subscriber with different cliend ID receives 5 messages that were
> intended for the clientID "1". However, this does not mean that client ID "1"
> will not receive the 5 messages when it comes back online. I noticed that
> client ID "1" also received the 5 message.
> Now that both clientID 1 and 2 received messages, subscribing a new clientID
> doesn't receive these message. However, if we send 5 message again to the
> topic and do not consume it for all clientIDs, it would delivered to any new
> subscription.
> For new client Id broker must create new session, so messages sent after
> client 1 disconnected should route to client 1 only since client 2 because it
> was connected after those 5 messages were sent (hence the new session of
> client 2 shouldn't contain old messages).
> Here are sample codes to reproduce:
> The producer Python script
> {code:python}
> import paho.mqtt.client as mqttClient
> import time
> import ssl
> # context = ssl.create_default_context()
> Connected = False
> broker_address= "localhost"
> port = 1883
> user = "admin"
> password = "admin"
> def on_connect(client, userdata, flags, rc):
> if rc == 0:
> print("Connected to broker")
> global Connected #Use global variable
> Connected = True #Signal connection
> else:
> print("Connection failed")
> client = mqttClient.Client(client_id="producer",transport="tcp") #
> client.username_pw_set(user, password=password) #set username and password
> client.on_connect=on_connect
> # client.tls_set_context(context=context)
> client.connect(broker_address, port=port)
> client.loop_start()
> i=0
> while True:
> time.sleep(1)
> i=i+1
> client.publish("test/data", "This is my test msg 123.",2,False)
> print("Sent"+str(i))
> {code}
> The consumer Python script
> {code:python}
> import paho.mqtt.client as mqttClient
> import time
> import ssl
> Connected = False
> broker_address= "localhost"
> port = 1883
> user = "admin"
> password = "admin"
> def on_connect(client, userdata, flags, rc):
> if rc == 0:
> print("Connected to broker")
> global Connected #Use global variable
> Connected = True #Signal connection
> print(flags)
> client.subscribe("test/data",2)
> else:
> print("Connection failed")
> def on_message(client, userdata, msg):
> print(msg.topic+" "+str(msg.payload))
> client =
> mqttClient.Client(client_id="id2",transport="tcp",clean_session=False) #
> client.username_pw_set(user, password=password) #set username and password
> client.on_connect=on_connect
> client.on_message=on_message
> # client.tls_set_context(context=context)
> client.connect(broker_address, port=port)
> client.loop_start()
> while Connected != True:
> time.sleep(0.1)
> time.sleep(1000)
> {code}
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