{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://synacl.com/protocol/v1/schemas/device-status.json",
  "title": "Device reachability",
  "description": "Whether one device is reachable. A gateway publishes it on `<prefix>/devices/{deviceId}/status` for each device it polls; a directly connected device publishes it on `tenants/{tenantId}/devices/{deviceId}/status` (and should set it as its MQTT last will with `reachable:false`). Publish it retained. A gateway's child device is marked offline 90 s after it was last seen, so a gateway should republish `reachable:true` (or data) at least every ~30 s for each healthy device.",
  "type": "object",
  "required": [
    "ts",
    "reachable"
  ],
  "properties": {
    "ts": {
      "description": "Epoch milliseconds.",
      "type": "integer",
      "minimum": 0
    },
    "reachable": {
      "type": "boolean"
    },
    "reason": {
      "description": "Why the device is unreachable, e.g. `timeout`, `crc`, `lwt`.",
      "type": "string",
      "maxLength": 128
    }
  },
  "additionalProperties": false
}