OASIS Message Queuing Telemetry Transport (MQTT) TCIcon indicating the project type

OASIS Message Queuing Telemetry Transport (MQTT) TC

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  1. OASIS Message Queuing Telemetry Transport (MQTT) TC
  2. MQTT-209

QOS 2 delivery options must not be mixed

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 3.1.1
    • Fix Version/s: 3.1.1
    • Component/s: core
    • Labels:
      None
    • Proposal:
      Hide

      Following call (03.04.2014). Paul Freemantle proposes:

      "The choice of Method A or Method B is implementation specific. As long as an implementation chooses exactly one of these approaches, this does not affect the guarantees of a QoS 2 flow."

      Previously:
      The diagram is now non normative but change it to show Method A and Method B, clarify the either one method or the other must e followed.

      Show
      Following call (03.04.2014). Paul Freemantle proposes: "The choice of Method A or Method B is implementation specific. As long as an implementation chooses exactly one of these approaches, this does not affect the guarantees of a QoS 2 flow." Previously: The diagram is now non normative but change it to show Method A and Method B, clarify the either one method or the other must e followed.
    • Resolution:
      Hide

      Resolved in WD23

      Show
      Resolved in WD23

      Description

      The QOS 2 delivery description says the following:

      "Figure 4.3 shows that there are two ways in which QoS 2 can be handled by the receiver. They differ in the point within the flow at which the message is made available for onward delivery. The choice of approach is implementation specific and does not affect the guarantees of a QoS 2 flow."

      Unfortunately while it is true that if you choose one approach it doesn't affect the guarantee, it seems like if you mix the two then messages can be lost. An academic I know did a formal analysis and proved this (I'll find a reference for you).

      Therefore I would recommend that we clarify this.

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          andrew_banks Andrew Banks (Inactive) added a comment -

          Corrected in WD24

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          andrew_banks Andrew Banks (Inactive) added a comment - Corrected in WD24

            People

            • Assignee:
              Unassigned
              Reporter:
              pzfremantle Paul Fremantle (Inactive)
            • Watchers:
              2 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved: