This is a very simple application that generates arbitrary fake values (e.g. coming from sensors) and serves them via json-files, mqtt or http requests. I use it to simulate dezentralized analytics scenarios, but it can be adapted for any other purpose where fake data sources are needed.
- Build with nodejs
- configurable via simple json file
- easily extensible (Add your own field types and custom value generators)
- provides values via a http interface or writes results in json files
- simulate as many sensors/data sources as you need with only one running instance
1. Configuration
Change the config.json.sample to config.json in the root directory and edit it to fit your needs. Find more information about the config.json below.
2. Run the application
2.1 Run local
You can run the application easily with node app.js from the root directory (take care that a config.json file exists).
As soon as the application is running you can see the logs in the console.
2.1 Run the application in a docker container
You can also simply run the application in a docker container with the image julianereth/a-atom-generator. For this simply run
docker run -v /localpath/to/your-config.json:/usr/src/app/config.json -p 8000:8000 -d julianereth/a-atom-generator
3. Access data
3.1. Access via http
You can easily access the data sources with your browser at http://localhost:8000/##sourceid##. The ##sourceid## part has to be replaced with the id you choose in your config.json e.g. http://localhost:8000/thermometer
The response will be a json string similar to something like this:
{"name":"thermometer","temperature":22,"humidity":8}
3.2. Write results in file
In the file mode the results are written in the output directory e.g. output/##sourceid##.json. Each source gets its own file.
3.3. Access via mqtt
Mqtt is a light-weight publish-subscirbe protocol often used in the Internet of Things. This application publishes the generated values and uses the the belonging source id as topic name. To publish messages you need a mqtt broker. To test your scenario you can use a free test broker like test.mosquitto.org. However, you can define your own broker in the config.json.
3.4 Fallback: console output
If no or an unknown mode is defined the application just prints the output in the console.
The main configuration contains the following elements
1. settings defines global settings.
1.1 mqtt > broker a mqtt broker. Requiered if you want to use mqtt in your scenario.
2. Sources defines the actual components in your scenario (e.g. data sources like machines and the like).
2.1. id sets the name of your source.
2.2. publish_intervall defines the interval in milliseconds (e.g. 5000 = 5s) how often a message of an atom will be published
2.3. mode sets the way you access the values. Current modes are file, console and http. If not set console is used as default.
2.4. fields: a json array of the fields that the data source incorporates.
2.4.1 name: name of a certain field in your source (e.g. a particular sensor).
2.4.2 generator: used generator to fill the values of this field (details below).
2.4.3 parameters: used to configure the generator (details below).
Currently the following value generators are implemented
1. currentTimestamp returns the current timestamp. (no additional parameters necessary)
2. floatRange Fallback generator that simply returns a random float value. . (parameters [from, to, decimal])
3. integerRange Fallback generator that simply returns a random integer value. (parameters [from, to])
This project is part of an ongoing research at the University of Stuttgart and will be a tool to simulate analytics scenarios in the context of the Internet of Things. Feel free to use this generator for any purpose or to contribute and with enhancements or new field types or generators. If you have any questions don't hesitate to contact me or use the Github issue tracker.
- Related Docker Image: Docker image to run this application
- fakesensor: A similiar project implemented in Java
- Analytical Atoms Specs: A specification of the underlying idea of analytical atoms (in work)