UDP Timeouts Revisited

I know this is probably rehash of things that have already discussed, but I am having trouble wrapping my head around it.

I am using a third party module with a Hologram SIM. In our application, what we want is the module to connect Hologram cloud, and then basically check for a UDP (cloud->device) messages, respond with a UDP message (if one is received) and then act upon the message (flip a relay, light an LED, etc). The messages need to be acted upon right away so the connection and UDP channel needs to be nailed up all the time. The caveat as is that there may be as many as dozen messages or as few as zero messages in a 24 hour period. There will always be long periods (hours) of no messages.

I’ve done some limited testing where I establish a connection and move UDP messages to/from the module. And that all seems to work fine but I am doing it over a very short period of time.

The question is what is going to happen over a long period of time when there is no traffic? Does the UDP channel get torn down? Does the connection get torn down?

In reading the forums, it sounds like the UDP channel will be torn down and the Cloud will no longer be able to send UDP messages to the module.

If that is true, then what are the options?

Thank you, Jim

On our devices, we have a setting that restarts the UDP listener every 15 minutes or so to address the problem you listed. You can also have your sender periodically send a byte or so of information over the channel to keep it open.

Interesting- If I might ask, if you restart the UDP listener (which I presume is the cell module) every 15 minutes or so, how is the situation handled when a route to the cell module is unavailable (timed out) and a message needs to be sent to the cell module?

Your second option sounds workable, although that would depend on the number of cell modules in the field. If you have a 100 cell modules in the field, that sounds workable, 10,000, maybe not so much.

Anyhow, thank you for your comments.

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