Which broker to use upon disconnection

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joes...@gmail.com

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Mar 4, 2019, 1:14:11 PM3/4/19
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Greetings all,


From reading the spec, it appears each client should keep a list of brokers, so that client can move to the next broker if it loses connection.  I’m wondering if there is a convention to follow when selecting the next broker to use.  For example, should I always run sequentially through the list, or should I perhaps have an order of preference?


For example, lets say a client has three configured brokers.  It starts by connecting to broker #1.  Later it loses that connection and connects to broker #2.  If it loses connection to #2, is it typical to try #1 again (as a preferred broker) or try #3 then #1?

Andy Stanford-Clark

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Mar 5, 2019, 4:37:36 AM3/5/19
to 'Simon Walters' via MQTT
yes, we’ve used the “hunt list” concept a lot in SCADA-type applications… just clicking round to the “next” broker in the list, so everyone is clear where they’re going next, 

It’s good to have the back-end applications simultaneously connected to ALL the available brokers in the list, so they can still talk to devices that haven’t moved yet.
This is because a new device coming in (or rebooting, say), will not know everyone moved, and so will start at broker #1 again.

Managing the availability of brokers in the list can be used to “nudge” everyone back onto the same broker, if needed.

Andy



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joes...@gmail.com

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Mar 5, 2019, 12:50:27 PM3/5/19
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Ok, specific use case: I'm a dev at AutoSol & we are adding publishing via MQTT of data polled using traditional protocols.  I'm not sure if you're familiar with our ACM product, but it's a polling engine, so we're essentially acting as a giant EoN node.  Users can use whatever broker they choose, so we won't have control over availability there.  So, would publishing to all brokers simultaneously be perferred in this situation?
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