SAP HANA XS and SAPUI5 - how to live update a chart?

Question

Hi all,
we are developing with SAP HANA Developer Edition and SAPUI5.
We read data with an XSJS File out of the Database ( i read the recent 40 datasets of the table with an SQL statement and LIMIT).
This is the code in my controller.js which calls the XSJS service that reads the data out of HANA DB.
loadChart: function() {
        var model = new sap.ui.model.json.JSONModel();
        var aUrl = '../../../dev/data_HANAXS/services/readdata.xsjs?cmd=loadChart';
        jQuery.ajax({
            url: aUrl,
            method: 'GET',
            dataType: 'json',
            success: function(data) {
                model.setData({modelData : data});
        return model;
Then in my view.js i set the model for the line chart and i can see my data.
var model = oController.loadChart();
linechart.setModel(model);   
What i want to do now is to live update the chart in regular time intervals, i am using SETINTERVAL ( you can also use jQuery.sap.delayedCall ) for that:
function updateChart() {
            var model = oController.loadChart();
            linechart.setModel(model);
setInterval(updateChart, 5000); // every 5 seconds refresh the chart
And this works fine BUT the COMPLETE CHART (including x-axis and y-axis) is drawn again every 5 seconds , what i want to know is how can i realize it so that ONLY the DATA LINE is drawn again every 5 seconds?
It would be great if anyone could help me regarding this issue?
It must be possible to do a live update of a chart especially for cases where you get steadily new data that has to be visualized.
Regards & Thanks,
Andreas

Answer 1

Hi Micha,
yes i tried that some days before but it did not work. After your message here, i tried it again but same result, what i get after some seconds is "No Data". Moreover i am not quite sure how to set the data with model.setData().
What i do is the following, maybe you know if there is a mistake: this is the code for updating the chart in the controller.js:
update: function(oController) {
        var model = new sap.ui.model.json.JSONModel();
        var aUrl = '../../../xxxx.xsjs?cmd=loadChart';
        jQuery.ajax({
            url: aUrl,
            method: 'GET',
            dataType: 'json',
            success: function(data) {
                model.setData({modelData : data});
                oController.onUpdateCall(model, oController);
onUpdateCall: function (updateJSONModel, oController) {
        oController.updateModel = updateJSONModel;
        var linechart = sap.ui.getCore().byId("linechart");
        var oModel = linechart.getModel();
        var oUpdateData = oController.updateModel.getData();
        oModel.setData(oUpdateData);
I use the same cmd parameter and i call the same xs service method "loadChart" (which always returns the newest datasets - data is continuosly pushed in our HANA DB) that initially loads the data for the chart.
I get no error messages in my browser.
When i do oController.update(oController) in my view.js after 5 seconds, i get "No Data" but analysing the data in browser shows me that the xs service returns the data, so data is definitely there.
Regards & Thanks,
Andreas