UNS OpenHubDocumentation

Schema administration

Understand and create an attribute type

An attribute type defines the shared meaning and data shape of a value, such as temperature or state. Use this guide when inspecting an existing definition or creating one; neither action publishes a value or creates a live topic by itself.

Applies to
Schema · Attribute type · View, Edit, and New
Guide version
1.0

Worked example

Example: temperature

Use this for numeric temperature readings that should be charted consistently wherever they occur.

Attribute key temperature

Stable identifier shared by compatible attribute paths.

Label / description Temperature

Readable canonical wording for administrators and consumers.

Value type number

Tells consumers that the value is numeric.

Preferred unit °C

The canonical display unit when a compatible measurement unit is available.

Presentation kind chart

Makes Explore and dashboards start with a time-series chart.

Default aggregation avg

Default summary when chart data is sampled into time buckets.

Procedure

Follow the task in order

  1. 1
    Choose a canonical keyUse a lowercase business term such as temperature. Do not put an asset name, ObjectId, or MQTT topic path in the key.
  2. 2
    Describe the shared meaningThe label and description should apply to every compatible attribute path, not only one current publisher.
  3. 3
    Set the data shapeChoose the value type, preferred unit, presentation kind, and aggregation that consumers should use before they see live values.
  4. 4
    Use translations and aliases only when usefulThey provide alternate human terms; they do not create extra attributes or rename a publisher's topic.
  5. 5
    Review discovered updatesA microservice may later discover a missing attribute or report another description. Keep the canonical definition deliberate and review any variants.

Expected result

What you should have

A reusable attribute definition. Live publishers can use compatible paths and values with this meaning later; this action does not change MQTT packets or historical data.

Boundaries

Important boundaries

  • Do not create a separate type for every asset-specific temperature topic unless their meanings or shapes are genuinely different.
  • Changing an active type's data shape can change how Explore, dashboards, and history present existing paths.
  • For a package-owned attribute type, choose Edit package definition from Schema. The change remains a package candidate until it is reviewed and applied.

This versioned public guide is maintained with the UNS OpenHub website and linked directly from the controller where the task applies.