David Z. created AMQ-7045:
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Summary: Lost messages when send from amq to mqtt client
Key: AMQ-7045
URL: https://issues.apache.org/jira/browse/AMQ-7045
Project: ActiveMQ
Issue Type: Bug
Affects Versions: 5.15.3
Environment: h1.
Reporter: David Z.
We use a Java Tomcat application which publish / subscribe jms messages to
Active mq and a Android Mobile application which is connected via mqtt to amq.
When a Mobile client lost its connection in some case persistent messages get
lost. I observerved this behavoiur with different mqtt clients. Here are two
cases to reproduce this bug.
h1. Case 1
Two clients: Client A connected over mqtt and Client B connected via jms
# Client A Subscribe to amq topic with Qos 2 and cleanSession = false
# Client B publish Message to topic with persistant flag = true
# Client A receive Message with Qos 0
# Disconnect client A (Turn on Airplanemode on Android)
# same as in step 2
# wait several minutes (longer as keep alive intervall)
# same as step 2
# Connect client A again (Turn off Airplane mode on Android device)
# Client A reiceives only message sent in step 7 with Qos = 0, message from
step 5 is lost.
h1. Case 2
See
[https://stackoverflow.com/questions/27189086/activemq-lost-persistent-message-sent-to-detached-consumer-before-keepaliveinter/52096122#52096122]
h1. Expected Behavoiur
Messages with persisant flag = true will sent to mqtt client with qos = 1 or 2
(delivered at least once or exactly once)
Messages with persistant flag = false will sent to mqtt client with qos = 0
(delivered 0 or 1 time)
h1. Bug
For me it seems that in File MQTTProtocolConverter on line 588 the constants
QoS.AT_MOST_ONCE and QoS.AT_LEAST_ONCE are swapped.
The line should look like
{{qoS = message.isPersistent() ? QoS.AT_LEAST_ONCE : QoS.AT_MOST_ONCE ;}}
instead of
{{qoS = message.isPersistent() ? QoS.AT_MOST_ONCE : QoS.AT_LEAST_ONCE;}}
A nice feature is when the user can change the mapping between Qos and
Persistant Flag in the configuration file.
[https://git-wip-us.apache.org/repos/asf?p=activemq.git;a=blob;f=activemq-mqtt/src/main/java/org/apache/activemq/transport/mqtt/MQTTProtocolConverter.java;h=ff6ee4335a4d27d665d4012f3b85c0ea3b31cfc2;hb=HEAD]
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