Model File Reference

The data model is described in JSON (or YAML) files placed in a single directory. All files in the directory are merged before validation, so you can split the model across as many files as you like. Only the top-level keys Groups, Datapoints, Structs, Enums, and Types are recognised.

groups.json

Defines one or more groups. Each datapoint belongs to exactly one group. A group carries a baseId — the base address for the ID space — and a version used by the serialization layer.

{
  "Groups": [
    {
      "name":        "DefaultGroup",
      "persistence": "None",
      "baseId":      "0x4000",
      "version":     "1.0.1",
      "description": "Default group with no persistence."
    },
    {
      "name":        "CyclicGroup",
      "persistence": "Cyclic",
      "baseId":      "0x5000",
      "version":     "2.0.0",
      "description": "Group persisted cyclically to external memory."
    }
  ]
}

Field	Required	Description
name	Yes	Unique group name. Used as the C++ variable name in the generated header.
baseId	Yes	Base address (hex string or integer). All datapoint IDs in this group are offset from here.
version	Yes	Semantic version string "major.minor.build" used for deserialization version checks.
persistence	No	One of "None" (default), "Cyclic", "OnWrite".
description	No	Human-readable description (informational only).

datapoints.json

Defines the individual datapoints.

{
  "Datapoints": [
    {
      "name":      "test",
      "group":     "DefaultGroup",
      "id":        1,
      "type":      "int32_t",
      "default":   4211,
      "access":    "READ_WRITE",
      "namespace": "Testify",
      "version":   "1.0.1",
      "description": "Test int32_t datapoint."
    },
    {
      "name":    "test4",
      "group":   "CyclicGroup",
      "id":      4,
      "type":    "Temperature",
      "default": { "value": 123.0, "raw": 5555 },
      "access":  "READ_WRITE",
      "version": "1.0.0"
    }
  ]
}

Field	Required	Description
name	Yes	Unique name within the group.
group	Yes	Name of the group this datapoint belongs to.
id	Yes	Offset from the group’s baseId. Must be unique within the group.
type	Yes	One of the C++ base types (int32_t, float, bool, …), a defined struct name, enum name, or alias type name.
default	No	Default value. For struct types use a JSON object with one key per struct field. For array types use a JSON array.
access	Yes	"READ_ONLY", "WRITE_ONLY", or "READ_WRITE".
namespace	No	Optional C++ namespace for the generated global variable.
version	No	Semantic version "major.minor.build" for the datapoint (default "0.0.0").
description	No	Human-readable description.

structs.json

Defines custom struct types that can be used as datapoint types. Structs can contain scalar fields or other struct fields (nested structs).

{
  "Structs": [
    {
      "name": "Temperature",
      "parameter": [
        { "value": "float" },
        { "raw":   "uint32_t" }
      ]
    },
    {
      "name": "Environment",
      "parameter": [
        { "internal": "Temperature" },
        { "external": "Temperature" }
      ]
    }
  ]
}

enums.json

Defines custom enum types. Two modes:

Auto-ID ("autoId": true) — values assigned starting at 0:

{
  "Enums": [
    {
      "name":   "Status",
      "type":   "uint32_t",
      "values": ["Booting", "Starting", "Finished"],
      "autoId": true
    }
  ]
}

Explicit values ("autoId": false) — each entry is a { "EnumeratorName": intValue } object:

{
  "Enums": [
    {
      "name":   "ErrorStates",
      "type":   "uint32_t",
      "autoId": false,
      "values": [
        { "None": 0 }, { "Info": 1 }, { "Warn": 4 },
        { "Error": 5 }, { "Critical": 9 }, { "Fatal": 10 }
      ]
    }
  ]
}

types.json

Defines alias types — thin wrappers around a base type with optional compile-time range bounds.

{
  "Types": [
    {
      "name": "AliasTypeUint32t",
      "type": "uint32_t",
      "min":  100,
      "max":  200
    },
    {
      "name": "AliasTypeFloat",
      "type": "float"
    }
  ]
}

When "min" and "max" are present, DataLayer::Detail::checkValue() enforces the range on every set() call and returns DataLayer::Detail::RangeCheck:

• underflow if the value is below min

• overflow if the value is above max

• ok if within range

YAML Support

All model files can be written in YAML instead of JSON. The generator accepts any mix of .json and .yaml / .yml files in the model directory. Use --convert to convert an existing JSON model to YAML. </content> </invoke>