Plenty of Things - A framework for monitoring and telemetry handling for embedded & low-level devices

This project is designed around providing various edge clients that can be loaded onto embedded or low-power devices which can then read sensor data and push these results up to a cloud system.

Communication

All communication is based on the IPSO standard, meaning all inputs and ouputs are driven by the relative object/resource IDs.

MQTT

The MQTT framework is based on an 'udge' system, where each letter is the action that is being performed.

• u
  • Send data up from the data to the MQTT broker
• d
  • Send data down from the MQTT broker to the device
• g
  • A request from the MQTT broker to the device that will cause the next up payload to include all of the resources requested
  • This is used to read values from resources that are not normally sent up on every up push
• e
  • A request from the MQTT broker to the device that will trigger the event resources listed

The MQTT topics look like this:

device/{deviceId}/{udge}/{messageType}(/{messageFormat})?

• {deviceId}
  • The id of the device that was given on registration
• {udge}
  • One of u, d, g, e
• {messageType}
  • Currently only ipso
  • Messages on this topic can be either JSON or BSON, so listeners should support both
• {messageFormat}
  • One of json, bson
  • Only used if configured on registration, otherwise it will be completely omitted

Payloads

The payload looks like this (described using TypeScript-like syntax):

interface Payload<T> {
  id: integer;
  instance: integer;
  timestamp: integer;
  resources: T;
}

In this payload, T depends on the udge request being performed. For u and d, it is

type ud = Record<integer, string | integer | float | boolean>

For the keys, JSON only allows strings, however they are always the resource ID (integer).

For g and e, T is

type ge = Array<integer>

Where each item is the resource ID to be requested, or to trigger.

Timestamp

All timestamps are in standard unix time using seconds.