This repository contains the (working) specification for Signal K, defined in JSON Schema files.

The Free and Open Source universal marine data exchange

SignalK is about publishing a common modern and open data format for marine use. A format for the modern boat, compatible with NMEA, friendly to WiFi, cellphones, tablets, and the Internet. A format available to everyone, where anyone can contribute.

Find out more at signalk.org. Then join the mailinglist by sending an email to [email protected] or follow the discussion via the Signal K Google Groups forum.

The master branch contains the latest version of the Schema. When making changes, please clone this repo to your local machine and set up a new branch (git checkout -b branch_name). Send in a pull request for every change, put it up for discussion in the mailing list and then (when a consensus has been reached) merge it into master.

The gh-pages branch contains the currently published version of the Schema. Once changes have been approved and merged into master and we are ready to publish an update, checkout the gh-pages branch and then checkout the schema directory from master on top of it:

git checkout gh-pages
git checkout master schemas/
git commit -m 'Copy schema from master'
git push

It will be published at http://signalk.github.io/specification automatically.

You can browse the Schema using the supplied docson viewer. Just open index.html from a local webserver (otherwise the XHR requests won't work) in your preferred browser to get started.

Validation against SignalK schema can be done

• with a command line validator accepting JSON from stdin
• by explicitly calling validate packaged as an npm module
• by using a Chai assertion, available in the npm module

As you can see in the example below the current implementation assumes that the input is a subtree under vessels.mmsi path.

echo '{"navigation":{"courseOverGroundTru":{"value":70.1,"source":{"label":"","type":"NMEA2000","pgn":"130577","src":"160"},"timestamp":"2014-08-15-10:01:35.236"},"speedOverGround":{"value":0.01,"source":{"label":"","type":"NMEA2000","pgn":"130577","src":"160"},"timestamp":"2014-08-15-10:01:35.236"}}}' | bin/validate.js
Unknown property (not in schema):/vessels/230099999/navigation/courseOverGroundTru

var validate = require('signalk-schema').validate;
var result = validate(msg);
  result.errors.forEach(function(error) {
    console.error(error.message + ':' + error.dataPath);
  });

chai.use(require('signalk-schema).chaiModule);
tree.should.be.validSignalK;