Looking for advice on how to

General
1

I'm being asked to build an app on a multitech conduit using node red.

It needs to do the following:

  1. Receive Lora messages
  2. Send them off to a web service
  3. If the send fails, resend.....without ever losing a msg

#1 and #2 are easy....i cant figure out a reasonably straightforward way to do #3

Thanks
Larry

2

Have you thought about utilising the catch/status nodes to start a flow for 3?
https://cookbook.nodered.org/basic/retry-on-error

3

I tried that but i am talking about potentially dozens of messages and it seems to have a limit. Additionally, are they persisted?

4

I suppose you receive an ack from the web service on successful transmission? And hopefully you always know the status of it?

I would just build up a FIFO "pile" of messages in context when transmission fails and as soon as the connection is working again, resend them again.

But,,,

  • you may have to think about the order messages are sent
  • should you go for FIFO or LIFO?
  • what if connection is broken and then suddenly works? Should you send the current message first or should you work through the pile first?
  • do you need to think about messages getting "too old", could it happen they become obsolete after a while?
  • do you have to consider total number of messages to keep?
  • what if the web service is down for a longer period?

Where do we send the bill for this consultancy?

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