clarifcation on JIRA 197 (was: RE: [mqtt] Groups

Hi All,

I have a question on the minutes for JIRA MQTT-197 on request/reply:

First apologies for not being able to attend this meeting and thus not partaking in the discussion, but I’d be grateful if someone could provide a bit more detail on what was discussed and what the proposed “good practice guidance” is that would not require protocol changes?

Per the JIRA, if you have an MQTT client talking to another non-MQTT endpoint (maybe AMQP or proprietary but the point is with different topic/subscription capabilities), how can the MQTT and non-MQTT applications effect a request/reply interaction?

If the MQTT endpoint puts an MQTT reply-to topic into the MQTT payload, then (a) the broker can’t see it since it doesn’t understand the application message format so cannot do any interworking with the non-MQTT protocol and (b) since it is an MQTT topic this addressing structure verbatim might not be available to the non-MQTT app that needs to send a reply.

Same occurs in the reverse direction for an MQTT endpoint receiving a request with a reply-to address in the payload that is not valid over MQTT.

For context – below is the section from the minutes.

Thank you

Shawn

https://issues.oasis-open.org/browse/MQTT-197

This JIRA requests that the version of the MQTT protocol after 3.1.1 be augmented to support the request/reply message exchange pattern.

N. O’Leary: Request/Reply could be defined as a 'good practice' over a protocol feature.

P. Niblett: Possible preference for a light touch on request/reply to keep MQTT concise/lightweight.

P. Duffy adds that this is an interesting feature. Good practice guidance could be helpful for Restful services.

P. Niblett and A. Stockdill-Mander: It could make a good committee note.

A. Stockdill-Mander proposes that the TC explore this as a Committee Note which might be merged into the spec at a future point if it makes sense to do that.

Proposed A. Stockdill-Mander.

Seconded W. Cox. No Objections.

TC approve

From: mqtt@lists.oasis-open.org [mailto:mqtt@lists.oasis-open.org] On Behalf Of Julien Niset
Sent: March-04-15 5:46 AM
To: mqtt@lists.oasis-open.org
Subject: [mqtt] Groups - OASIS_MQTT_TC_minutes_12022015.pdf uploaded

Document Name: OASIS_MQTT_TC_minutes_12022015.pdf

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Submitter: Mr. Julien Niset
Group: OASIS Message Queuing Telemetry Transport (MQTT) TC
Folder: Meeting Notes
Date submitted: 2015-03-04 02:46:10

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