creatingWidgets.md

Creating Widgets

A widget is basically a factory function wich returns a EventEmitter instance. These EventEmitter have to trigger a data event each time the widget wants to update its data. There a many ways to trigger this event like streams, webhooks or basically an interval function which requests data from another server.

To register a new widget we need a Plugin at first. This plugin must require the widgetManager to be injected. Once we have the widgetManager we can add our factory function with the register() method.

var events = require('events');

module.exports = function(widgets) {

    widgets.register('clock', function(options) {
        var emitter = new events.EventEmitter;
        
        // generate data and call emitter.emit('data', some Data)
        
        return emitter;
    });
};

module.exports.$inject = ['widgetFactory'];

Unlike the plguin function which is called one time the plugin was loaded, our widget factory will be called each time a widget is added to a board. This gives us great control to decide when a code has to be executed.