woobagooba / specification

Signal K is a JSON-based format for storing and sharing marine data from different sources (e.g. nmea 0183, 2000, seatalk, etc)

Signal K Specification

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

Usage

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 rebase it on top of master:

$ git checkout gh-pages
$ git rebase master

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

Docson

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

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/signalk-validate
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;

Signal K

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.

To get started, see the summary page and have a look through Navgauge Issue #4 to get a feel for where we started. Then join the mailinglist by sending an email to [email protected] or follow the discussion via the Signal K Google Groups forum.