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[paho-dev] How to use the cleanSession parameter and persistence mechanism for mqtt publisher(publishing messages at QOS 1)


I have recently started learning eclipse Paho(Java client).And I have executed the MqttPublishSample from

I have few doubts regarding the cleanSession parameter and persistence mechanism.

1.If a MQTT client is only publishing messages to topics with QOS 1, does the cleanSession parameter need to set as false ?
Session maintenance is required?If yes why?

2.How persistence mechanism helps in achieving QOS 1 for a MQTT Publisher?

2.1 In what way MemoryPersistence mechanism helps in achieving QOS.

2.2 If MQTT client disconnects(connection lost) during publishing, what will be the role of persistence mechanism w.r.t QOS 1.
For the published messages for which PUBACK message is not received?Paho API will handle the QOS 1 requirement?

2.3 How a MQTT async publisher will know QOS1 is not achieved for particular message.i.e PUBACK message is received.

3.In order to use persistence mechanism do I need to set the cleanSession parameter as true? I want to know if there
is any co-relation between the two? or both are independent feature.

Note:- All the questions I have asked is from the view point of developing a MQTT  Publisher client.


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