[paho-dev] Does order of MqttClient's methods matters?

[Sigmund Lee <wuaner@xxxxxxxxx>]

I am planing build a Push Notification service using RabbitMQ + Paho client. I noticed that method setCallback() of MqttClient must invoke before connect() & subscribe(), otherwise Non-clean-sessioned messages that publish since last connection disconnect will not be processed. Does that mean order of MqttClient's methods matters?

And any other points I must be aware when using Paho MQTT java Client?