overview
Whenever data on the data bus changes, the platform calls $imports on all components. For any component that imports the data that has changed on the bus, the $update method is called.
That is, suppose the component implements the following $imports method:
this.$imports = function () {
return ['data1','data2'];
}
Then, whenever either data1 or data2 is set on $val (as in the following code), this components $update method will be called.
$val.set('data1', [1,2,3,4,5]);