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correlation ID

A label a command carries so its reply can be matched back to it.

A correlation ID is a unique value attached to a request and echoed in its response, so a requester with several outstanding requests can pair each response with its request.

Examples

  • The app publishes command c-50 ("fan 30 %") to gh1/<device-id>/cmd/req, and the node answers on gh1/<device-id>/cmd/res with c-50 ok, so the app knows which request that reply belongs to.

See also

request/response over pub/sub command message ID
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