Azure Event Hubs are a high-throughput, real-time data ingestion service. We can think of it as a big, scalable entry point for streaming data — telemetry, logs, sensor data, clickstreams, IoT signals, etc. A typical use case in factory environments would be telemetry or sensor data from machines. This article describes the basic concepts and how typically the data is flowing from what to where in a very good way.
For Peakboard application there are basically too touchpoints:
- Peakboard can act as source of events and stream these events to the Azure Event Hub
- Peakboard can also be a consumer of events and can react on incoming events it has subscribed to
We will discuss both directions in this article.
Set up the Azure environment
On the Azure side the set up is fairly easy. The frame for hanndling events is the Event Hubs Namespace. It bundles one or more Event Hubs. The next screenshot shows the namespace.
And below the Namespace is the one and only Event Hub. Within the Event Hub we will need an access policy. From the access policy we get the connection string that we will need later to configre the data source on the Peakboard side.
The last Azure object is a Storage Account. It is needes and used to store the offset points for the message streaming. The csreenhot show how to get the connection string. We will need it later.
Set up the Peakboard flow for Sending messages.
On the Peakboard side - regardless if we use it in Flow or a regular design project - We must provide the connection string for both the Event Hub and Storage account along with the Hub name and the storgae account name.
The idea of our Flow is to build a bridge between a machine and the Event Hub. So we also need the connection to the machine. It’s very simple by using an OPC UA data source. We will subscribe to two OPC UA nodes that each repesents a counter of a light barrier. It’s just counting the goods that pass through the light barrier. So our data source has two columns for the two light barriers that contain the counters.
The next screenshot shows the actual flow. It’s triggered by the OPC UA data source. So every time one of out two light barriers sends an updated value the flow is triggered. And very time it’s triggered it calls the function SendToAzure.
Here’s the last step we need to get it working. The SendToAzure funtion just calls the function sendevent of out Azure Data Hub source. It takes two parameters. The first parameter is the actual message. In our case we just build a JSON string to encapsulate the two light barrier counter values. The second parameter is a set of properties that can be seend as some kind of meta information that is bound to the actual message. These properties can be used with the Event Hub in Azure for message routing or other logic. For out example we don’t use these. So the code in the screenshot is only for demonstration purpose on how to use it.
After having the Flow deployed on a Peakboard Hub server it will work right away and send all subscribed light barrier values to a Azure Event Hub.