Equivalent of layer.redraw(true) in OpenLayers 3?

I have a geojson layer in my OL3 app which I want to redraw every 5 seconds (to show movement on map) .

How do I do it ? Couldn't find the equivalent of Layer.redraw().

Answer

This is how you can refresh a vector source every 5 seconds, from a web service returning features in a GeoJSON document:

var vectorSource = new ol.source.Vector();
var geojsonFormat = new ol.format.GeoJSON();

window.setTimeout(function() {
  $.ajax('http://example.com/data.json', function(data) {
    var features = geojsonFormat.readFeatures(data

        {featureProjection:"EPSG:3857"});
    geojsonSource.clear();
    geojsonSource.addFeatures(features);
  });
}, 5000);

jQuery is used here for requesting the data through Ajax ($.ajax), but you can obviously use the library of your choice.

This code snippet also assumes that the map's projections is "EPSG:3857" (web mercator) and that the coordinates in the GeoJSON documents are longitudes and latitudes.