Hi Rob,
it's very probable that these are bugs, and should be raised as
such. My plan was to have MQTT-SN added to Mosquitto, and a
transparent MQTT-SN gateway in Paho, rather than continue
development on RSMB, but the Mosquitto plans are taking longer than
expected, so fixing some bugs in RSMBs MQTT-SN support is
possible. I hope to start work on the Paho transparent gateway
very soon though.
I have a couple of questions about what you've described (below):
Ian
On 11/05/2014 05:54 PM, Rob Shewan
wrote:
Hi,
I have been
working with RSMB in the Linux environment developing a
client based upon the Paho Embedded C code.
I would like to
receive feedback on a number of observations that seem to
be counter to the MQTT-SN specification, namely:
- The broker will forward a published message after an
Unsubscribe has been performed and the Unsubscribe Ack
received.
This is possible in both MQTT-SN and MQTT, if the message is queued
up and is delivered to the receiver at a later point, such as when
it reconnects. Could you give more details about this scenario and
the next one? By forwarding, do you mean to the same application
that sent the message? Is this still using MQTT-SN? Is a bridge
involved?
- The broker won't forward published messages after the
client has Unsubscribed and then re-Subscribed.
- The QOS of the published messages is not that which
was returned by the Subscribe message sequence but the
QOS of the publisher of the message. The QOS returned in
the Subscribe Ack message is ignored by the broker.
The QoS should be the maximum of the QoS at which the message was
published and the requested QoS in the subscribe. So if you
subscribe with QoS 2, then every message will be received at the QoS
at which it was published. If you subscribe with QoS 1, then QoS 2
messages will be downgraded to QoS 1. If you subscribe with QoS 0,
then all messages will be received at QoS 0. It's not working like
that?
- There is no trace output for received PUBREL messages.
- There is no trace output for received UNSUB messages.
If I am wrong
about any of these or they are know problems, I apologize.
If they are problems that should be addressed I would be
happy to enter them as bugs if desired.
Thanks,
Rob Shewan
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--
Ian Craggs
icraggs@xxxxxxxxxx IBM United Kingdom
Paho Project Lead; Committer on Mosquitto
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