Use · How-to

Rules: react to device messages

Select messages with SQL, filter them, and send them on to topics, HTTP endpoints, queues, twins or other devices. Test before you save.

Updated 11 Nov 20262 min read

All ThingsX IoT Core pages

A rule watches a topic, picks the fields you want, filters with WHERE, and runs one or more actions on every match.

SELECT temperature, topic(3) AS device
FROM 'tic/things/+/telemetry'
WHERE temperature > -15

Functions you can use

Function	Returns
`topic(n)`	The nth part of the topic (`topic(3)` of `tic/things/freezer-1/telemetry` is `freezer-1`)
`topic()`	The whole topic
`clientid()`	The client ID that sent the message
`timestamp()`	When the message arrived, in milliseconds

+ matches one topic level and # matches the rest.

Action	Use it to
Republish	Send the result to another topic, for example `alerts/freezer`
HTTP	Call your webhook or API with the result as JSON (with headers you choose)
Queue	Send to a message queue for your backend to process
Twin	Update a device's twin
Command	Send a command to a device

If an action fails, the message goes to the rule's dead letters, where you can see the error and replay it once the cause is fixed.

Open Rules. Give the rule a name (letters, digits and underscores).
Write the SQL.
Paste a sample topic and sample payload, then press Test. You see whether it matches and what each action would receive.
Add the actions and Save rule.

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