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  1. OASIS Message Queuing Telemetry Transport (MQTT) TC
  2. MQTT-573

Subscription Options

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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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      Issue 576 introduces the subscribe flags field.

      Table 19 - change Flags to Subscribe Flags

      Section 5.4.15 SUBSCRIBE

      • Length and MsgType: see section 5.2
      • Subscribe Flags:
        • QoS: the requested QoS level for the subscription
        • No Local: see section 5.3.6
        • Retain as Published: see section 5.3.6
        • Retain handling: see section 5.3.6

      Section 5.4.16 SUBACK

      Table 20 - change ''Flags' to 'Subscribe Flags'

      Field list: change 'Flags' to 'Subscribe Flags'. QoS is the only field used, with the same description as that existing.

      Section 5.4.17 UNSUBSCRIBE

      Field list: change 'Flags' to 'Subscribe Flags'. All unused apart from TopicIdType

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      Issue 576 introduces the subscribe flags field. Table 19 - change Flags to Subscribe Flags Section 5.4.15 SUBSCRIBE Length and MsgType: see section 5.2 Subscribe Flags: QoS: the requested QoS level for the subscription No Local: see section 5.3.6 Retain as Published: see section 5.3.6 Retain handling: see section 5.3.6 Section 5.4.16 SUBACK Table 20 - change ''Flags' to 'Subscribe Flags' Field list: change 'Flags' to 'Subscribe Flags'. QoS is the only field used, with the same description as that existing. Section 5.4.17 UNSUBSCRIBE Field list: change 'Flags' to 'Subscribe Flags'. All unused apart from TopicIdType

      Description

      Subscription options were added to MQTT 5.0. These are generally well received. Similar capabilities should be added to MQTT-SN especially as they can result in more efficient operations.

      Subscribe flags field:

      2 bits - max QoS as now
      1 bit - noLocal
      1 bit - retain as published
      2 bits - retain handling
      2 bits - topic ID type

      (I think DUP is not needed on subscribe - rely on suback).

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            • Assignee:
              ian.craggs Ian Craggs
              Reporter:
              ian.craggs Ian Craggs
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              Dates

              • Created:
                Updated:
                Resolved: