Visualizing Azure IoT Edge using local dashboard

In my last series of blogs, we first looked at how to deploy a non-IoT Edge module using Azure IoT Edge.

For this example, I used a NodeJS website running SocketIO. It was possible to access this website with a default SocketIO chat application.

After that, we looked at how to add some charts in the HTML page offered by the NodeJS server.

Let’s see how we can combine this all into one solution. Let’s build a local for raw Azure IoT Edge telemetry.

Continue reading “Visualizing Azure IoT Edge using local dashboard”


Show telemetry in NodeJS using SocketIO and HighCharts

In my previous blog, I showed you how to host NodeJS in a Docker Image.

Today we will learn how we show telemetry in NodeJS. The message will arrive as a string on an HTML page using SocketIO and we will put it on a chart from HighCharts.

This is a great example of how we can represent raw data in something useful, something end user will understand.

We will extend our previous example. In that example, we were leaning on NodeJS and we have the Express web framework running to show an HTML page. We added SocketIO so users of the index.html can exchange messages.

But what if the incoming message is


a JSON message on a single line? And it is shown as a string?

Nice, but this is only good for nerds like me.

What if we could represent it as:

a chart?

This a much better solution, isn’t it?

Continue reading “Show telemetry in NodeJS using SocketIO and HighCharts”

Deploying a NodeJS server with SocketIO to Docker using Azure IoT Edge

The current Azure IoT Edge public preview uses Docker to deploy logic from the cloud into local gateways. It’s currently featuring:

  • C# modules written in .Net standard
  • Python modules
  • Azure Function built on your machine
  • Azure Stream Analytics jobs built and deployed in the cloud
  • Azure Machine Learning

We can expect Microsoft will support other types of modules soon as they have proven with other recent projects. An Azure Cognitive Services module is a good example, it’s put in every IoT Edge presentation.

The IoT Edge portal makes it possible to deploy modules which are available in private or public image repositories.

Could it be possible to build and deploy images to the gateway which are not specifically designed for IoT Edge?

It turns out, it is possible.

Let’s deploy a NodeJS server which serves SocketIO.

Continue reading “Deploying a NodeJS server with SocketIO to Docker using Azure IoT Edge”

User Defined Function in Stream Analytics

Azure Stream Analytics provides a great solution for temporal queries of streams of data. The query language is pretty simple, especially if you have a background in SQL queries.

The list of built-in functions is a long list, ranging from aggregation, analytics, geospatial, records, scalars to the recently introduced anomaly detection.

But what if you want to write your own functions?

Stream Analytics supports three types of custom functions:

  1. user-defined functions (UDF) written in Javascript
  2. user-defined aggregates (UDA) written in Javascript
  3. Machine learning endpoint disguised as functions

In this blog, I will show how easy it is to write and use your own custom logic in a Stream Analytics job. We will look at the user-defined functions.

Continue reading “User Defined Function in Stream Analytics”

Using Node.js to access Azure IoT Hub

By now the Cloud strategy of Microsoft must be very clear. It’s not about Windows, it’s not about Office, it’s not about Microsoft programming languages even. Microsoft is opening up towards all devices, operating systems, programming platforms, etc. Everybody is welcome in the cloud.

Although this is going on for quite some time, it is still a surprise for quite a few non-Microsoft developers. So today I decided to program against the Azure IoT Hub using another language, just to check out their experience.

Microsoft supports multiple programming languages, there are multiple SDK’s available:

If your favorite language is not listed here, but it talks MQTT, AMQP or HTTP, chances a big you can build your own SDK.

Today I picked up Node.js because I know a bit of javascript 🙂 Let’s check out what Javascript developers have to do to connect to an Azure IoT Hub.

Continue reading “Using Node.js to access Azure IoT Hub”

Introduction to Tessel combined with Azure EventHub

Last month, during the Azure Bootcamp, I was introduced in programming the Tessel.

This device is a fairly cheap IoT programming board and for me, the most remarkable feature was that it was running on JavaScript.


Yes, everybody with the basic understanding of JavaScript can start programming the Tessel.

My main goal for  that day was putting some effort in Azure EventHubs but first I did the ‘hello world’ of the Tessel called Blinky.js

// Import the interface to Tessel hardware
var tessel = require('tessel');
// Set the led pins as outputs with initial states
// Truthy initial state sets the pin high
// Falsy sets it low.
var led1 = tessel.led[0].output(1);
var led2 = tessel.led[1].output(0);
setInterval(function () {
  console.log("I'm blinking! (Press CTRL + C to stop)");
  // Toggle the led states
}, 100);

It was not that intuitive to get this working (I had to install node.js etc) but the convenience of JavaScript is very nice. So just follow the scripted examples.

Then I tried out and combined two other hands-on labs:

These HOLs helped me to explore how I can send messages to the EventHub. And I was surprised how easy it was to send JSON data into the EventHub. And now I can imagine how the EventHub is just a VERY BIG bucket in which Azure MessageBus messages are off-loaded. And I can image how the data can be investigated by StreamInsight for a couple of days before the data gets steel and is deleted.

So finally, just for fun, I came up with this continuous probing and sending:

var https = require('https');
var crypto = require('crypto');
var climatelib = require('climate-si7020');
var tessel = require('tessel');
var climate = climatelib.use(tessel.port['A']);

climate.on('ready', function () {
  console.log('Connected to si7005');

climate.on('error', function(err) {
  console.log('error connecting module', err);

// Event Hubs parameters
console.log('Please ensure that you have modified the values for: namespace, hubname, partitionKey, eventHubAccessKeyName');
console.log('Please ensure that you have created a Shared Access Signature Token and you are using it in the code')

var namespace = 'SvdvEh-ns';
var hubname ='svdveh';
var deviceName = 'mytessel';
var eventHubAccessKeyName = 'SendRights';
var createdSAS = 'SharedAccessSignature sr=[...]';

console.log('Namespace: ' + namespace);
console.log('hubname: ' + hubname);
console.log('publisher: ' + deviceName);
console.log('eventHubAccessKeyName: ' + eventHubAccessKeyName);
console.log('SAS Token: ' + createdSAS);

var SendItem = function(payloadToSend){
  // Send the request to the Event Hub
  var options = {
    hostname: namespace + '',
    port: 443,
    path: '/' + hubname + '/publishers/' + deviceName + '/messages',
    method: 'POST',
    headers: {
      'Authorization': createdSAS,
      'Content-Length': payloadToSend.length,
      'Content-Type': 'application/atom+xml;type=entry;charset=utf-8'

  var req = https.request(options, function(res) {
    console.log("statusCode: ", res.statusCode);
    res.on('data', function(d) {

  req.on('error', function(e) {


setImmediate(function loop () {
  climate.readTemperature('f', function (err, temp) {
    climate.readHumidity(function (err, humid) {
      console.log('Degrees:', temp.toFixed(4) + 'F', 'Humidity:', humid.toFixed(4) + '%RH');
      var payload = '{\"Temperature\":\"'+temp.toFixed(4)+'\",\"Humidity\":\"'+humid.toFixed(4)+'\"}';
      setTimeout(loop, 5000);

This code was enough to see how the EventHub was filled with data. I had no time to check out StreamInsight. But it seems very easy to write some SQL-like code to get the right information out of the hubs.

The biggest problem was the administration of all the namespaces, keys, connection strings and secrets of both the MessageBus and the EventHub. Sometimes I had to cut/copy/paste parts of connection strings but that was not that intuitive.

And the Tessel? It was real fun to play with. And the complete humidity/temperature sensor was easy to plug in (had to fix the code because it was referencing another module type). But somehow I missed the spider web of wires and components and the accidental reboots of the RaspberryPi 🙂

A special mention goes to the free service bus explorer. It was very exciting to see messages coming in live. Very useful for debugging too.

jsTreeview in ASP.NET MVC gevuld met Json action

Op dit moment heeft jQuery UI nog geen treeview control. Als alternatief zijn er enkele andere aanbieders van Treeview controls. In het verleden heb ik al eens bericht over de Telerik controls. Deze kan ik zonder meer aanbevelen maar helaas zijn de gratis extensies alleen voor open source projecten toe te passen.

Een andere treeview is de jsTreeview. Deze is heel aardig (ondersteunt ajax, de jQuery themes en bv. ook checkboxes). Helaas is de deocumentatie nogal fragmentarisch. Daarom geef ik hier een opstap hoe jsTreeview is toe te passen in ASP.NET MVC. We maken hierbij gebruik van Json actions om de kinderen op te vragen vanuit de controller.

Stap 1: Bestanden plaatsen

Haal eerst de laatste versie op vanaf . Dit is de versie pre 1.0 fix 2.

Plaats in het ASP.NET MVC4 project de jquery.jstree.js in de \Scripts map.

Plaats d.gif (voor ie6 gebruik), d.png, styles.css en throbber.gif in \Scripts\themes\treeview map.

Stap 2: bundles aanpassen

Vul de bundles aan in de BundleConfig.cs:

bundles.Add(new StyleBundle("~/Scripts/themes/treeview").Include(
bundles.Add(new ScriptBundle("~/bundles/jqueryplugins").Include(
                        [skip other plugins],

En deze bundles moeten op de _Layout.cshtml aangeroepen worden:

 @Scripts.Render("~/bundles/jquery", "~/bundles/jqueryui", "~/bundles/jqueryplugins")

Stap 3: HTML placeholder

Plaats een placeholder op de _Layout.cshtml

<div id="treeviewEdit"> Tree view placeholder</div>

Stap 4: JavaScript

Plaats daarna het volgende  script onder aan de _Layout.cshtml pagina  om te worden uitgevoerd als de pagina laadt (dit moet dus in een javascript blok):

$(function () {
        "json_data": {
            "ajax": {
                "url": "/Home/FillEditTree",
                "data": function (n) {
                    return { id: n.attr ? n.attr("id") : 0 };
        "themes": {
            dots: false,
            icons: true
        "plugins": ["themes", "json_data"]


Deze jQuery functie zal op de treeview div losgelaten worden om het treeview tekenen te forceren.

Stap 5: de (view) modellen

We praten straks in Json formaat met de treeview, maar we willen dit in typed classes samenstellen. Voeg dus de volgende viewmodellen toe:


De code wordt dan:

public class JsTreeModel
    public JsTreeData data { get; set; }

    public JsTreeAttribute attr { get; set; }

    // "open" or "closed" or null (not available for ajax)
    public string state { get; set; }

    public List<JsTreeModel> children { get; set; }
public class JsTreeAttribute
    public string id { get; set; }
public class JsTreeData
    public string title { get; set; }

    public JsTreeDataAttribute attr { get; set; }

    // "folder"  or "/" for no icon thus file
    public string icon { get; set; }
public class JsTreeDataAttribute
    public string href { get; set; }

Laatste stap 6: Controller action

Voeg de volgende action toe aan de controller. Deze geeft ter demonstratie als antwoord altijd de opgevraagde node met daaronder twee kinderen. De eerste keer wordt node 0 opgevraagd. het eerste kind heeft zelf ook kinderen (niet meegestuurd in deze aanroep) en de tweede heeft geen kinderen:

public ActionResult FillEditTree(int id)
    // just to show some nodes
    var rootId = id + 2;

    var children = new List<JsTreeModel>();

    // first child containing one or more children
        new JsTreeModel
                attr = new JsTreeAttribute { id = (rootId + 1).ToString() },
                data = new JsTreeData
                            title = "Child " + (rootId + 1).ToString(),
                            attr =
                                new JsTreeDataAttribute
                                        href =
                                            + (rootId + 1).ToString()
                state = "closed",

    // second child containing NO children
        new JsTreeModel
                attr = new JsTreeAttribute { id = (rootId + 2).ToString() },
                data = new JsTreeData { icon = "/", title = "Child " + (rootId + 2).ToString(), },

    // de ‘root’
    var requestedSubTree = new List<JsTreeModel>();

            new JsTreeModel()
                attr = new JsTreeAttribute { id = rootId.ToString() },
                state = "open",
                data =
                    new JsTreeData
                            title = "Title " + rootId.ToString(),
                            attr =
                                new JsTreeDataAttribute { href = @"\home\edit\23" }
                children = children

    return Json(requestedSubTree, JsonRequestBehavior.AllowGet);

Dit geeft het volgende plaatje (na enkele keren kinderen opvragen):


Er zijn een aantal zaken die opvallen:

  • De ‘root’ moet standaard de state geopend (“open”) krijgen
  • Je moet dus onderzoeken of de getoonde kinderen op hun beurt ook kinderen hebben
    • De kinderen moeten standaard de state te openen (“closed”) krijgen als deze op hun beurt kinderen hebben.
    • Een kind zonder kinderen moet geen state krijgen (dus null). Dan komt er ook geen ajax call mogelijkheid.

Bonus stap 7: jQuery Thema

Als laatste in het rijtej plugins kan “themeroller” toevoegen worden.  Deze kan je toepassen als alternatief voor thema:

$(function () {
        "themes": {
            dots: false,
            icons: true
        "plugins": ["json_data", "themeroller"]

Dit geeft een aardige uitbreiding op het standaard aanwezige thema:


Bonus stap 8: cookies

Je kunt ook plugin “cookies” toepassen. Dan wordt bij een F5 de selectie bewaard en niet opnieuw opgevraagd. Maar de laatste kan ook op de server in de sessie onthouden worden en bij de initiële aanroep (node id is 0) toegepast kunnen worden.


Deze plugin is heel aardig om voor weinig geld en snel een treeview toe te passen in ASP.NET MVC.

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