@senseering/worker NPM

Motivation

Connecting IoT devices and services to management tools and anlytics can be cumbersome. The Senseering Worker provides a simple interface to the senseering world written in Node.js. Examples for common scenarios (e.g. MQTT, HTTP and OPC-UA) can be found in the given example repository.

Installation

This is a Node.js module available through the npm registry.

Before installing, download and install Node.js.

Installation is done using the npm install command:

npm install @senseering/worker

Worker Description

A worker is the basic building block for our approach to a decentralised data plattform. It utilizes the manager for storing, managing and selling our data on the senseering myDataEconomy-plattform. The workers objective is to process or generate data based on sensor inputs or other available feeds. It can be run as a source that only publishes data to your liking (e.g. send every few seconds the new sensor inputs) or as a service, which provides a service function that can be triggered on demand (e.g. a weather station that should only publish on demand or an image recognition service). Also a mixture of those two types is possible. This should give a short introduction to workers and the possible use cases. Below you can find more information to the config object and the api of worker_js.

Config object high level description

Property	Subproperty		Type	Description
credentials			String	Identifier for connection to manager in format ':'
url			String	Protocol and domain of manager
settings			Object	Some general settings on the worker's behaviour
	qualityOfService		Number	0: receive at most once, 1: receive at least once
	messageRetries		Number	Number of tries for sending of messages
	messageTimeout		Number	Number of milliseconds to wait until timeout of message
meta			Object	with key-value-pairs, meta field can be added to the data packages of this worker
payment			Object	Fixed price and boolean option for additional pricing
	fixCost		Integer	Fixed costs of the data packages
	isFixCostOnly		Boolean	Can additional costs apply?
profile			Object	General information on worker
	name		String	The fully qualified name by which the worker should be called
	location		Object	2D GPS coordinate of the worker
		latitude	Number	Latitude of worker location
		longitude	Number	Longitude of worker location
privKey		String	URI reference to the private key used to signing
schema		Object	Either single or community schema and boolean option for schema check on worker
	input	String	URI reference to the input schema in .json format
	output	String	URI reference to the output schema in .json format
info			Object	object containing all relevant information
	worker		Object	information for worker
		description	String	URI reference to the worker info in .md format
		tags	Array	tags under which this worker wants to be found
	input		Object	information for input data
		description	String	URI reference to the input info in .md format
		tags	Array	tags under which this worker wants to be found
	output		Object	information for output data
		description	String	URI reference to the output info in .md format
		tags	Array	tags under which this worker wants to be found

Worker API

worker.connect:

config (object): The config object of the worker

Sets up the connection to the manager, registers the worker and generates keys.

worker.publish:

data (object): Object that will be published

Publishes desired data on the manager

worker.provide:

service (function): function that returns data

Provides the service function that can be triggered on demand

worker.settings.get:

No parameters

Returns the current settings of the connection to the manager

worker.settings.update:

settings (object): New settings object for worker

Updates the settings of the connection of the worker to the manager (First use worker.settings.get and modify the resulting object, before handing it to worker.settings.update)

worker.meta.get:

No parameters

Returns the currently used meta data that are added to each published data point

worker.meta.update:

meta (object): New meta data object that will be added to each data point before publication

Updates the meta data

worker.disconnect:

No parameters

Stops the connection to the manager

Templates in workers

A detailed explanation to templates and the idea behind it can be found in the template_js repository. For the worker itself it is only needed to know that templates are a high level description of the exact data structure in JSON-LD Format. The incoming and outgoing data must be described in that way so every worker knows what to expect from the incoming data and is able to work on it.