Device Protocol

The device protocol defines the messaging that occurs between an IoT device and the PiBox server.

Registration

Registration is initiated by the IoT device. It sends a multicast packet to the PiBox server. The packet does not need to contain any information. It's purpose is to advertise the IP address of the IoT device.

The server captures the message and then queries the device for type, features and configuration which is stored in the piboxd daemon and to file as needed.

Queries

A query is made from the server to the IoT device using a web URL. The URL is of the format

  http://<ipaddress>/im/<version>/<command>

POST variables are used for arguments to the command.

Some commands are common to all devices.

  get: arguments include config, registration
  set: arguments include config

Other commands are specific to the device and can be identified in the config response.

Query Response

A query response is provided as JSON text in the body of the page returned to the caller. For a registration request the device returns it's identity and feature list. For a config request the device returns its current settings associated with the features it supports.

Identify

The identity is the device name. This is free format and is used to identify the device to the server.

Features

A device can specify a collection of features. A feature is a set of names and associated data types and values. The feature is defined by its name. The feature name cannot have the "-" character. All other names prefixed with that name are associated with that feature. The data type (re: the JSON value) for the name and is one of num, text, range, or set. If a feature is of type of range then the range is specified as name-range. If the type is set then the set is specified as name-set. A feature can have a display name separate from the feature name, which is represented as name-display. The current setting for that feature is presented as the name-value. The following is an example using the underlying JSON formatted structure.

{
    "identity": "vent", 
    "features": {
        "damper":             "set", 
        "damper-display":     "Vent Damper", 
        "damper-set":         "0,25,50,75,100", 
        "damper-range":       "0-100", 
        "damper-value":       "25", 
    }
}

Features are the way a device specifies how it can be configured and what data it provides. The server can use this to dynamically build a UI for the device.

Config

The config response contains the current settings for the named features.

Control

Control of a device is through a config object. The configuration is changed by a UI application and forwarded to the IoT device. The device attempts to apply the configuration changes, which may or may not succeed. Success is not specified on a configuration change. The only way to know if the change was applied is to query the current configuration and compare it to the change request.