Keep Alive and Session Expiry Interval controls - (session leak)

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    • Type: Improvement
    • Resolution: Applied
    • Priority: Major
    • None
    • Affects Version/s: None
    • Component/s: MQTT-SN
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      We could look to bind the session expiry close to the last seen time of the client instead of the "Network Connection" thus the gateway has a reasonable place to start the close counting.

      We must mandate that the session expiry interval is > keep alive else you could have a situation where sessions are cleared up whilst the device still APPEARS to be ACTIVE.

      The KeepAlive 0 rule AND the session expiry interval 0xFFFFFFFFF meaning keep forever seems like an unwise choice for gateway devices.

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      We could look to bind the session expiry close to the last seen time of the client instead of the "Network Connection" thus the gateway has a reasonable place to start the close counting. We must mandate that the session expiry interval is > keep alive else you could have a situation where sessions are cleared up whilst the device still APPEARS to be ACTIVE. The KeepAlive 0 rule AND the session expiry interval 0xFFFFFFFFF meaning keep forever seems like an unwise choice for gateway devices.

      The "Keep Alive" and "Session Expiry Interval" behaviour defined in MQTT 5 applied "as-is" in MQTT-SN would be dangerous. Since the "Network Connection" cannot be used as a control vector to start session expiry clocks, this is a session memory leak.

            Assignee:
            thesii
            Reporter:
            simon.johnson1
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              Created:
              Updated:
              Resolved: