Managing change across a fleet.
WHAT WILL ALWAYS BE TRUE
Several firmware versions in the field simultaneously.
WHY
Devices miss updates, are offline, or fail to apply them.
WHAT THAT DEMANDS
A platform handling every version still deployed.
WHAT TO VERSION
Firmware The message schema The configuration schema The protocol itself, where it changes
WHAT TO REPORT WITH EVERY DEVICE
Its firmware and schema versions.
WHY
It is how the platform knows what to expect and what to send.
WHAT BACKWARD COMPATIBILITY REQUIRES
New platform versions accepting old messages New firmware accepting old configuration
WHAT THE SAFE CHANGES ARE
Adding optional fields Adding new message types
WHAT THE UNSAFE ONES ARE
Removing fields Changing types or units Repurposing existing fields
WHY UNITS ESPECIALLY
A silent unit change produces plausible wrong data.
WHAT TO DEFINE
A minimum supported version, and what happens below it.
WHAT TO DO WITH DEVICES BELOW IT
Prompt or force an update, rather than failing obscurely.
WHAT TO PLAN
How long each version is supported.
