Route Tutorial - ThingSpeak

Introduction

In this tutorial, you’ll learn how to connect your Notecard-powered app to an external cloud provider or service, ThingSpeak, and how to start creating simple visualizations with sensor data.

This tutorial assumes you’ve already completed the initial Sensor Tutorial to capture sensor data, save it in a Notefile called sensors.qo and send that data through the Notecard to Notehub; or, that you’ve already created your own app with sensor data and are ready to connect your app to external services.

In order to complete this guide, you’ll need the following:

• A Notehub project with at least one Notecard sending sensor-reading Notes at regular intervals.
• An account with the external service you plan to use to complete this tutorial.

Create a Route

A Route is an external API, or Server location, where Notes will be forwarded for a Device or Fleet upon receipt.

Routes are defined in Notehub for a Project, and can target a single Fleet or all devices in a Project. A Project can have multiple routes defined and active at any one time. Before you create a Route, ensure the data you want to route is available in Notehub, by navigating to the Events view.

We’ll start with a simple route that will pass Notecard events through to webhook.site, where you can view the full payload sent by Notehub. Using this service is a useful way to debug routes, add a simple health-check endpoint to your app, and/or familiarize yourself with Notehub's Routing service.

1. Navigate to webhook.site. When the page loads, you'll be presented with a unique URL that you can use as a Route destination. Copy that URL for the next step.

   

2. Navigate to the Notehub.io project for which you want to create a route and click on the Routes menu item in the left nav.

3. Click the "Add Route."

   

4. Give the route a name (for example, "Health"), and select "General HTTP/HTTPS Request/Response" for the Route Type.

   

5. For the Route URL, use the unique URL you obtained from webhook.site.

   

6. In the Notefiles dropdown, choose "Select Notefiles" and enter the name of the notefile to monitor. For example, we used sensors.qo for the sensor tutorial.

   

7. Make sure the Enabled checkbox is checked and click "Save."

   

8. Return to webhook.site. This page will update automatically with data from your Notecard as it is received in Notehub. The data from your sensor is contained within the body attribute. Notice that Notehub provides you with a lot of information, by default. In the next section, we’ll look at using transformations to customize what Notehub sends in a Route.

   

Use JSONata to Transform JSON

Before you move on to adding a route to another external service, let's briefly explore using JSONata to transform the data Notehub sends to a Route. As mentioned above, Notehub provides a lot of information in each Route request. You may want to trim down what you send to your external service, or you might need to transform the payload to adhere to a format expected by that service. Either way, Notehub supports shaping the data sent to a Route using JSONata.

About JSONata

JSONata is "a lightweight query and transformation language for JSON data." According to their docs, JSONata was inspired by XPath 3.1, so if you’ve done XML querying or transformation in the past, JSONata will feel familiar to you. Even if you’re unfamiliar, the syntax is simple and the docs are comprehensive, so you’ll find JSONata a great, flexible way to shape Routes as you need them. The JSONata team even provides a browser-based playground, which you can use to see what your query will produce. Simply paste a payload into the JSON window at the left, write your query at the right, which the lower-right window will evaluate live.

Transform Your Data

Let’s try a simple query to the webhook.site route you created in the last section.

1. Navigate to the Routes page in Notehub and click the edit (pencil) icon for your Route.

   

2. In the "Transform JSON" drop-down, select "JSONata Expression"

   

3. In the JSONata expression text area, add the following query to select the temp and humidity from the body, create a location field that concatenates the tower_location and tower_country fields, and create a time field.

{
 "temp": body.temp,
 "humidity": body.humidity,
 "location": tower_location & ', ' & tower_country,
 "time": when
}

4. Click Save. Then, navigate back to your webhook.site url. As requests come in, you’ll see your custom, JSONata-transformed payload in the Raw Content section.

   

JSONata is simple, powerful, and flexible, and will come in handy as you create Routes for your external services. To explore JSONata further, check out the docs at JSONata.org.

Route to an External Service

Now that you’ve created your first Route and learned how to use JSONata to shape the data sent by a Route, you'll connect Notehub to an external service.

For this tutorial, you’ll connect your app to ThingSpeak, a simple IoT analytics tool from MathWorks that provides simple dashboards and built-in visualizations for your projects.

Create a ThingSpeak Account

If you don’t have one already, first create a ThingSpeak account.

Create a Channel for Sensor Data

1. Once you’ve created an account and have signed in, head to the Channels dashboard and click on New Channel

2. On the New Channel screen, give your channel a name. Then, in each Field text box, add Temperature (C), Humidity, Location, and Time, respectively.

3. Click Save Channel. You’ll be taken to your Channel dashboard, which includes some pre-built, but empty charts. The next step is to get these connected to your Notehub project with a Route.

Create a Route in Notehub

1. To write to your ThingSpeak channel, you’ll first need your Write API key, which you can get from the "API Keys" tab. Copy your Write API Key for the next steps.

2. Open the Routes dashboard in Notehub and click the "Add Route" button.

3. Give the Route a name, keep the Route Type default, and enter https://api.thingspeak.com/update.json for the Route URL.

4. In the notefiles dropdown, select "Select Notefiles" and specify sensors.qo. Then, in the Transform JSON option, select JSONata Expression and enter the following expression. Be sure to change the api_key placeholder to match the value from your ThingSpeak channel.

{
    "api_key":"L7F5G2R4HAU3HUIO",
    "field1": body.temp,
    "field2": body.humidity,
    "field3": tower_location & ', ' & tower_country,
    "field4": when
}

Notice that we’re using field1, etc. to designate each key. ThingSpeak requires this structure when writing data to a channel, and anything beyond these values and api_key are ignored. field1 et al correspond to the field name you specified on the New Channel screen above.

5. Click Save and navigate back to your ThingSpeak channel dashboard. If everything is wired up correctly, the built-in field-specific charts will update as new values come in.

Build Data Visualizations

ThingSpeak has built-in visualizations for time-series data, which makes it an easy tool to get started with. You can edit the built-in visualizations to add a title, change the visualization type, and more. To check it out for yourself, click the pencil icon in the top-right of each chart widget.

It’s also possible to add your own widgets, or build complex visualizations using MATLAB. Let’s take a look at creating a simple gauge for the temperature value.

1. Click on the "Add Widgets" button on your channel dashboard.

2. Next, click the Gauge card and click Next.

3. Give the widget a name like "Current Temp", select "Field 1" as the data source, set the min to -20, max to 40, and use the plus sign button to add color-coded temperature ranges.

4. Click Save and the widget will be placed on your channel dashboard.

Congratulations, you’ve created your first Route and connected your Notecard app to an external service!