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  1. OASIS Message Queuing Telemetry Transport (MQTT) TC
  2. MQTT-65

Should the QoS flag for PUBREL, SUBSCRIBE and UNSUBSCRIBE be reserved ?

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    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 3.1.1
    • Fix Version/s: 3.1.1
    • Component/s: core
    • Labels:
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    • Proposal:
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      bits 2,1 (the QoS flag) of the fixed header for PUBREL, SUBSCRIBE and UNSUBSCRIBE are reserved and must be set to 0,1. The server MUST treat any other value as malformed and close the TCP Connection.

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      bits 2,1 (the QoS flag) of the fixed header for PUBREL, SUBSCRIBE and UNSUBSCRIBE are reserved and must be set to 0,1. The server MUST treat any other value as malformed and close the TCP Connection.
    • Resolution:
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      Resolved in WD10 Lines 868, 992, 1033

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      Resolved in WD10 Lines 868, 992, 1033

      Description

      The current spec is ambiguous with respect to the acceptable values of the QoS flag for PUBREL, SUBSCRIBE and UNSUBSCRIBE operations.
      It could be interpreted that QoS must be set to 1 to force an appropriate ACK. However the ACK behavior is described independently.

      do we accept only one value ?
      if so, should it be 0, 1 or 2?
      Are other values be treated as malformed?

      Forcing 0 would change the protocol flow on the wire.
      Forcing 1 is consistent with the spirit of the input spec, but we need some clarity. The intended ACK behavior is not really related to QoS.

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            • Assignee:
              Unassigned
              Reporter:
              coppen Richard Coppen (Inactive)
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                Updated:
                Resolved: