Robot Market · Quick reference
Three acknowledgements, three meanings
When a backend tells a caller that a device command is progressing, name the component that produced each piece of evidence.
Evidence map
| Evidence | Who produced it? | What it supports | What it does not prove |
|---|---|---|---|
| HTTP 202 | Go HTTP server | The request was accepted for processing. | Broker publication or device execution. |
| QoS 1 PUBACK | MQTT receiver on this hop | The corresponding QoS 1 PUBLISH exchange was acknowledged, subject to the reason code. | That a device accepted or completed the business action. |
| Command result | Device application, delivered back through MQTT | The result contract reports accepted, completed, or rejected work. | That the report is authentic without identity and authorization checks. |
API admission
HTTP 202
→
HTTP 202
Broker hop
PUBACK
→
PUBACK
Device application
Command result
Command result
Use this sentence
“The API accepted command C. The broker acknowledged the publish. The device result is still pending.”
If the API process keeps command state only in memory, an HTTP 202 is not a promise that the record survives a process restart.