AzureFunctions

MISSION GOAL : Repeating Signal

Our connectivity to Mars is slowly coming back online, but we have not yet made contact with the crew. In order to automate our communication attempts, we’re going to set up a repeating signal which pings the Mars base at regular intervals.

You’ll use Azure functions to accomplish this task, and ensure that when the crew regains access to their equipment they’re aware of our concerns here on Earth. Let’s get to work.

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MISSION OBJECTIVES

The main objective of this mission is to set up a repeating message which pings the Mars base. You will be working as a part of a team on this objective.

Your next task is to accomplish the following objectives:

1. Create a function from the quickstart
2. Test the function
3. Create a new Timer Based Function in the Azure portal
4. Add an Azure Queue Storage output
5. Add a JavaScript function which is triggered by the queue

Objective 1: Create a function from the quickstart

A function app hosts the execution of your functions in Azure. Follow these steps to create a new function app as well as the new function. The new function app is created with a default configuration. For an example of how to explicitly create your function app, see the other Azure Functions quickstart tutorial.

Before you can create your first function, you need to have an active Azure account. If you don't already have an Azure account, free accounts are available.

1. Go to the Azure Functions portal and sign-in with your Azure account.

2. Type a unique Name for your new function app or accept the generated one, select your preferred Region, then click Create + get started.

3. In the Quickstart tab, click WebHook + API and JavaScript, then click Create a function. A new predefined Node.js function is created.

   

4. (Optional) At this point in the quickstart, you can choose to take a quick tour of Azure Functions features in the portal. Once you have completed or skipped the tour, you can test your new function by using the HTTP trigger.

Objective 2: Test the function

Since the Azure Functions quickstarts contain functional code, you can immediately test your new function.

1. In the Develop tab, review the Code window and notice that this Node.js code expects an HTTP request with a name value passed either in the message body or in a query string. When the function runs, this value is returned in the response message.

   

2. Expand the right-hand side bar, and click on the Test header. In the Request body text box, change the value of the name property to your name, and click Run. You will see that execution is triggered by a test HTTP request, information is written to the streaming logs, and the "hello" response is displayed in the Output.

   

3. To trigger execution of the same function from another browser window or tab, copy the Function URL value, by clicking the "Get Function URL" link, and paste it in a browser address bar, then append the query string value &name=yourname and press enter. The same information is written to the logs and the browser displays the "hello" response as before.

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Objective 3: Create a new Timer Based Function in the Azure portal

1. In the Azure portal, create a new Azure Function (New / Compute / Function App).

   

2. Create a new function using a resource group and consumption plan.

   

3. The function app should be deployed in a minute or less. From the resource group overview, select the function app. Select Timer and C# and click the Create this function button. Select "Skip the tour and start coding" when the code window opens.

   

4. Click on the Integrate item in the tree view to view the Timer settings. The default timer schedule is set to run the function once every 5 minutes, since the cron expression will match whenever the current minute value is equal to 5.

   

5. Change this cron expression value to run every 5 seconds by changing the first value from 0 to */5, and the second value from */5 to * (as shown below) and clicking the Save button.

   

6. Click back to the Develop tab and check the Logs, which should show that the timer trigger is now executing every 5 seconds.

   

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Objective 4: Adding an Azure Queue Storage output

1. Click back to the Integrate tab, then click the New Output button.

   

2. Select Azure Queue Storage on the list, then click the Select button.

   

3. Rename the Message parameter name to output, change the Queue name to outqueue if it's not already that, and click the Save button (don't click the Go button, which will create a new function).

   

Note: The Message parameter name is important, since this will also be the name of the variable in the function code.

1. Click the Develop tab and change your function to take an out string output parameter and write to this value, as shown below. Click the Save button to save your changes.

   using System;
   
   public static void Run(TimerInfo myTimer, out string output, TraceWriter log)
   {
       log.Info($"C# Timer trigger function executed at: {DateTime.Now}");    
       output = "Attention Fourth Horizon crew. Please respond and confirm status.";
   }

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Objective 5: Adding a Node Function Which Is Triggered By The Queue

1. Click the + New Function button on the left side. Filter the Language to JavaScript and select QueueTrigger - JavaScript from the list.

   

2. Set the Queue name to outqueue, ensure that the Storage account connection is set to AzureWebJobsStorage, and click Create.

   

3. You'll see that this Function template is already set up to read an item from the queue and log the value:

      module.exports = function (context, myQueueItem) {
       context.log('Node.js queue trigger function processed work item', myQueueItem);
       context.done();
   };

4. When the function starts up, you should see several entries written to the logs with the message your previous timer based function was writing to the storage queue.