What Happens When Your IoT Device Loses Internet?

Here's something that's easy to forget when building an IoT prototype:

The internet is not guaranteed.

Your device works perfectly in testing.

Then the Wi-Fi disappears.

What now?

One simple option is to drop the readings.

That's fine if the data isn't important.

Another option is local buffering.

Something like:

Sensor
↓
Local storage
↓
Internet unavailable
↓
Keep collecting
↓
Connection returns
↓
Send stored readings

But then another question appears.

What if local storage fills up?

Do you delete the oldest data?

Keep only important readings?

Stop collecting?

There's no universal answer.

It depends on the application.

That's what makes IoT different from some normal web applications.

You have to design around failure as part of the normal operating environment.