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  1. OASIS Message Queuing Telemetry Transport (MQTT) TC
  2. MQTT-576

Separate flags fields for connect, publish, subscribe

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    Details

    • Type: Improvement
    • Status: Applied
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: MQTT-SN-1.2
    • Fix Version/s: None
    • Component/s: MQTT-SN
    • Labels:
      None
    • Proposal:
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      5.3.4 Flags

      Rename section 5.3.4 to Publish Flags

      Remove will and cleansession from both the diagram in table 4 and the list underneath.  Leave remaining fields where they are - will and cleansession become reserved.

      5.3.5 Connect Flags

       

      Capabilities
      (3)
      Authentication
      (2)
      Will
      (1)
      Clean Session
      (0)
      • Capabilities: indicates capability exchange to follow
      • Authentication: indicates authentication exchange to follow
      • Will: (as in current section 5.3.4)
      • Clean Session: (as in current section 5.3.4)

       

      5.3.6 Subscribe Flags

      No Local
      (7)
      QoS
      (6,5)
      Retain as Published
      (4)
      Retain Handling
      (3, 2)
      TopicIdType
      (1,0)
      • QoS: maximum QoS. This gives the maximum QoS level at which the Server can send Application Messages to the Client. It is a Protocol Error if the Maximum QoS field has the value 3.
      • No Local: if the value is 1, Application Messages MUST NOT be forwarded to a connection with a ClientID equal to the ClientID of the publishing connection
      • Retain as published: If 1, Application Messages forwarded using this subscription keep the RETAIN flag they were published with. If 0, Application Messages forwarded using this subscription have the RETAIN flag set to 0. Retained messages sent when the subscription is established have the RETAIN flag set to 1.
      • Retain handling. This option specifies whether retained messages are sent when the subscription is established. This does not affect the sending of retained messages at any point after the subscribe. If there are no retained messages matching the Topic Filter, all of these values act the same. The values are:
        • 0 = Send retained messages at the time of the subscribe
        • 1 = Send retained messages at subscribe only if the subscription does not currently exist2
        • 2 = Do not send retained messages at the time of the subscribe.
        • It is a Protocol Error to send a Retain Handling value of 3.
      • TopicIdType: (as in current section 5.3.4)

       

       

       

       

       

       

       

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      5.3.4 Flags Rename section 5.3.4 to Publish Flags Remove will and cleansession from both the diagram in table 4 and the list underneath.  Leave remaining fields where they are - will and cleansession become reserved. 5.3.5 Connect Flags   Capabilities (3) Authentication (2) Will (1) Clean Session (0) Capabilities: indicates capability exchange to follow Authentication: indicates authentication exchange to follow Will: (as in current section 5.3.4) Clean Session: (as in current section 5.3.4)   5.3.6 Subscribe Flags No Local (7) QoS (6,5) Retain as Published (4) Retain Handling (3, 2) TopicIdType (1,0) QoS: maximum QoS. This gives the maximum QoS level at which the Server can send Application Messages to the Client. It is a Protocol Error if the Maximum QoS field has the value 3. No Local: if the value is 1, Application Messages MUST NOT be forwarded to a connection with a ClientID equal to the ClientID of the publishing connection Retain as published: If 1, Application Messages forwarded using this subscription keep the RETAIN flag they were published with. If 0, Application Messages forwarded using this subscription have the RETAIN flag set to 0. Retained messages sent when the subscription is established have the RETAIN flag set to 1. Retain handling. T his option specifies whether retained messages are sent when the subscription is established. This does not affect the sending of retained messages at any point after the subscribe. If there are no retained messages matching the Topic Filter, all of these values act the same. The values are: 0 = Send retained messages at the time of the subscribe 1 = Send retained messages at subscribe only if the subscription does not currently exist2 2 = Do not send retained messages at the time of the subscribe. It is a Protocol Error to send a Retain Handling value of 3. TopicIdType: (as in current section 5.3.4)              

      Description

      To support new features of authentication https://issues.oasis-open.org/browse/MQTT-568, subscribe options https://issues.oasis-open.org/browse/MQTT-573, and capabilities https://issues.oasis-open.org/browse/MQTT-566, more flags are needed than are available in the current flags byte.

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            • Assignee:
              ian.craggs Ian Craggs
              Reporter:
              ian.craggs Ian Craggs
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              • Created:
                Updated:
                Resolved: