Constraints

This structured item provides a mechanism for determining the availability and valid range of a scalar item dependent on the value of one or more other scalar items.

Definition

ID	constraints
Qualified ID	org.esta.lib.core.1/constraints
Name	Constraints
Description	Contains markup defining availability and valid ranges of scalar items
Category	N/A

Discussion

This structured item contains an object with some number of key/value pairs. Each key is a unique identifier for a constraint group array which is its value. Each constraint group contains valid combinations of scalar items and scalar item values for a set of dependent scalar items.

A single scalar item instance in a device class shall only be included in one constraint group, contained within an instance of a constraints data item and shall appear in all child combination arrays contained within that constraint group.

A combination array contains a number of child objects, which refer to scalar items and their values, which are considered valid alongside the other scalar items and respective values in the same combination.

Controllers and visualizers can use these combinations to establish the availability, and valid range of a scalar item dependent on the value of one or more other scalar items.

Combination Child Detail

Key	Description
scalaritem (required)	Indicates the ID of the scalar item for which this range provides valid values
min (required)	A minimum valid value for the scalar item. A null value means this scalar item is unavailable
max	A maximum valid value for the scalar item. Must not be included if min is a null value

The minimum attribute defines a minimum valid value for the scalar item. It applies in different ways when combined with different data types:

When applied to…	Minimum indicates…
number	The number’s minimum value.
string	N/A
binary	N/A
boolean	The valid value (true/false)
enum	The minimum case index.
object	N/A

The maximum attribute defines a maximum valid value for the scalar item. It applies in different ways when combined with different data types:

When applied to…	Maximum indicates…
number	The number’s maximum value.
string	N/A
binary	N/A
boolean	N/A
enum	The maximum case index.
object	N/A

Markup Structure

{
  "constraintGroup1": [
    [
      {
        "scalaritem": "/scl/scalar-item-1-id",
        "min": 0,
        "max": 1
      },
      {
        "scalaritem": "/scl/scalar-item-2-id",
        "min": null
      },
      {
        "scalaritem": "/scl/scalar-item-3-id",
        "min": null
      }
    ],
    [
      {
        "scalaritem": "/scl/scalar-item-1-id",
        "min": null
      },
      {
        "scalaritem": "/scl/scalar-item-2-id",
        "min": 0,
        "max": 1
      },
      {
        "scalaritem": "/scl/scalar-item-3-id",
        "min": 0.1,
        "max" 10
      }
    ]
  ]
}

Definition Markup

{
  "udrtype": "structureditemclass",
  "id": "constraints",
  "name": "Constraints",
  "description": "A mechanism for determining the availability and valid ranges of scalar items.",
}

Instance Example

{
  "udrtype": "structureditem",
  "class": "org.esta.lib.core.1/constraints",
  "id": "standard-constraints",
  "access": "readonly",
  "lifetime": "static",
  "value": {
    "constraintGroup1": [
      [
        {
          "scalaritem": "/scl/shutter",
          "min": 0,
          "max": 1
        },
        {
          "scalaritem": "/scl/strobe-waveform",
          "min": null
        },
        {
          "scalaritem": "/scl/strobe-frequency",
          "min": null
        }
      ],
      [
        {
          "scalaritem": "/scl/shutter",
          "min": null
        },
        {
          "scalaritem": "/scl/strobe-waveform",
          "min": 0,
          "max": 1
        },
        {
          "scalaritem": "/scl/strobe-frequency",
          "min": 0.1,
          "max": 10
        }
      ]
    ]
  }
}