[OASIS Issue Tracker] (MQTT-235) NoLocal Subscription for MQTT Subscribers

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    [ https://issues.oasis-open.org/browse/MQTT-235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=61542#comment-61542 ] 

Ian Craggs commented on MQTT-235:
---------------------------------

Alex,

thanks for the offer, sorry it's taken so long for me to respond.   Firstly I will add my views on this topic. 

It is correct to state that this is not the only function required for bridging.  The other one, as I see it, is the propagation of the retained flag on publications.   (If there are any others, it would be good to note them here.)   Even with a nolocal option for subscriptions, message loops are possible in cyclical multi-hop broker configurations.   So nolocal is very helpful if not essential for bridging, but not an ultimate fix.  

I think that a nolocal option is useful beyond bridging, and for that reason I would vote for a flag on subscribe, rather than connect.

If we think that the primary use case is for bridging, then perhaps this issue ought to be refactored as concerning bridging, and consider all the aspects involved.

I am happy to continue the discussion here, or arrange one or more calls for interested parties.


> NoLocal Subscription for MQTT Subscribers 
> ------------------------------------------
>
>                 Key: MQTT-235
>                 URL: https://issues.oasis-open.org/browse/MQTT-235
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: New Feature
>          Components: futures
>    Affects Versions: 3.1.1
>            Reporter: Rahul Gupta
>            Priority: Critical
>             Fix For: 3.1.1
>
>
> Based on a query in MQTT Google group, a query was posted with a requirement that the server should not publish message to a subscriber if messages are published by the same client-id and subscribed by the using the same client-id for the same topic. In this case a client connection may both publish and subscribe to a topic and the subscriber should inhibit the delivery of messages published by its own connection. This feature is available in JMS and a subscriber can inhibit to receive publication by using the noLocal flag during subscription.
> This feature is also needed to enable bridging and making proxy subscription between servers so as to stop messages going round in loops.
> I would like propose to add a element in SUBSCRIBE Control packet for individual subscriptions to make a choice on noLocal parameter.  This field could be shared in the same byte as for requstedQos. 



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