Some MQTT-SN working draft questions and answers

I had some comments to a blog post of mine.Â I repost the questions and my answers here:

Questions:

(Referring to working draft 8)

1. Regarding the message types are detailed in Table 2-1. The direction of flow is conveyed from Client to gateway. But while explaining these control packets you mention communication client to server or server to client. I got lost there.

2. Another point is in some places, the draft is mentioning the gateway or server. As per my understanding, they both are separate entities, and the gatewayâs main task is to convert MQTT-SN to MQTT and vice-versa.

3. In this draft we left the method of assigning clientID to the gateway, if we want to align it with MQTTv5, then why we are not letting the server generate a client and send it in CONNACK?

4. Last, section 8 âSafety, Security, and Data Protection Considerationsâ, should we expect more content in this section or will be a separate document for this?

My answers:

1. One of the remaining pieces of work we have to do is to clean up terminology. In MQTT-SN we do use the terms gateway and server interchangeably, but hey do have somewhat different meanings â an MQTT-SN gateway can be implemented as a standalone utility or as part of an MQTT broker. The term âserverâ encompasses all types of MQTT-SN gateway implementation. But we should be clear.

2. See 1. âServerâ includes âgatewayâ in my mind.

3. That is the intention â maybe it wasnât clear. It should be clear in the latest draft (https://www.oasis-open.org/apps/org/workgroup/mqtt-sn/download.php/69227/mqtt-sn-v2.0-wd11.docx)

4. We havenât finalized this but I expect we will have some content in this placeholder section. We are also considering an implementation guide (name and form to be decided) that could contain additional information.

Ian Craggs CEng MBCS CITP

Eclipse Paho project lead; Eclipse IoT PMC; MQTT-SN OASIS TC chair

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