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https://issues.apache.org/jira/browse/AMQ-5092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13930338#comment-13930338
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Dejan Bosanac commented on AMQ-5092:
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Hi Dhiraj,
I ran the tests with the patch and I think I see a regression.
{code}testResendMessageId(org.apache.activemq.transport.mqtt.MQTTSSLTest) Time
elapsed: 0.039 sec <<< ERROR!
java.net.ProtocolException: Command from server contained an invalid message
id: 2{code}
Wonder if you can reproduce this on your side?
> MQTT uses duplicate packet IDs for PUBLISH messages
> ---------------------------------------------------
>
> Key: AMQ-5092
> URL: https://issues.apache.org/jira/browse/AMQ-5092
> Project: ActiveMQ
> Issue Type: Bug
> Components: MQTT
> Affects Versions: 5.9.0
> Reporter: Dhiraj Bokde
> Assignee: Hadrian Zbarcea
> Fix For: 5.10.0
>
> Attachments: AMQ-5092.patch
>
>
> MQTT protocol converters does not correctly generate unique packet ids for
> retained and non-retained publish messages sent to clients. MQTT requires
> that all Publish messages with QoS > 0 must have a unique packet id which can
> be used by clients to coordinate the PUBACK, PUBREC, PUBREL and PUBCOMP
> messages depending upon the QoS flow.
> Although retained messages published on creation of client subscriptions are
> copies of retained messages, they must carry a unique packet id when
> dispatched to clients. ActiveMQ re-uses the retained message's packet id,
> which makes it difficult to acknowledge these messages when wildcard topics
> are used.
> ActiveMQ also sends the same non-retained message multiple times for every
> matching subscription for overlapping subscriptions. These messages also
> re-use the publisher's message id as the packet id, which breaks client
> acknowledgment.
> A patch is included, which fixes all the above scenarios. It generates a
> unique packet id for every publish (retained and non-retained), and also
> ensures that redelivery on the same connection will re-use message ids, with
> the dup flag set. The patch also maps JMS redelivery status for a
> subscription to the MQTT Dup flag to indicate duplicate messages. Unit tests
> are included to test correct packet id generation.
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