Introduction

In my last article, I gave an introduction to Azure Functions. Now, let’s move forward and get started with Azure Functions. In this article, I’m going to discuss how to create an Azure Function using the HTTP Trigger template and integrate it with Azure Queue Storage.

This is a continuation of my previous article. I highly recommend you to go through my previous article before going through this one.

What we will learn here?

  • Creating an Azure Function
  • Integrating a function with Azure Queue Storage

Creating a function

Log into the Azure portal and go to the Function Apps. Go to your existing function app which we created in my last article and click on the plus (+) icon to create a new function.
You will get all the predefined templates. Choose HTTP Tigger under "API and Webhooks" category, as shown in the below figure.

Figure 1: HTTP Trigger Template

Now, it will prompt the form to create a function. Give a function name, like I named it as QueueIntrgrationDemo, and click "Create". Now, Azure will start creating a new function.

Let’s create a function which will accept the order details as a JSON payload, deserialize it, and respond to the user. Replace the existing code with the code given below.

  1. public class Order{
  2. public string OrderId{get;set;}
  3. public string ProductId{get;set;}
  4. public string UserEmail{get;set;}
  5. public decimal Price {get;set;}
  6. }
  7. public static async Task<object> Run(HttpRequestMessage req, ILogger log, IAsyncCollector<Order> outputQueueItem)
  8. {
  9. string jsonContent= await req.Content.ReadAsStringAsync();
  10. var myOrder= JsonConvert.DeserializeObject<Order>(jsonContent);
  11. log.LogInformation($"Order {myOrder.OrderId} received from {myOrder.UserEmail} for product{myOrder.ProductId}");
  12. return (object)new OkObjectResult($"Your Order is Placed with Order Id {myOrder.OrderId}, Thank you" );
  13. }

Consider a scenario where the user placed the order. The order details are in a JSON payload and will be sent to the Azure Function we created. And, based on the above code, the JSON Payload will be deserialized and respond back to the user with a success message.

Now, we will extend this method to process the data further by integrating the Azure Queue Storage.

Integrating with Azure queue storage

Once the function is created, you can integrate, monitor, and manage it on the portal. Click on "Integrate". In the Integration window, you can see the Triggers, inputs, and outputs sections, as shown in the below figure.
Figure 2

Currently, we can have one trigger, i.e., HTTP Request, and one output, i.e., HTTP Response.

Figure 3
Select the Tigger as shown in the below figure. The Route template field is used to decorate the URL; the default route is api/functionName but we can customize it. In my case, I named it as neworder.
Select the HTTP method as POST, while the authorization level will be "Function".

Figure 4: HTTP Trigger

Now, just jump into the function and check whether the changes are reflected. Click on "get function URL".

https://myfunctionappdemos.azurewebsites.net/api/neworder?code=xQz5ZRPhRVCxOX4z5PoIGziXZVzxZuANgb5rJuGng1pI8A0ahR6Piw==

Got the URL? Now, you can see that based on the route template changes, the API URL is updated. Let’s test the API using POSTMAN.
Figure 5

Go to "Integrate" and let’s add one more output. Click on the new output and choose "Azure Queue Storage" and click "Select". Click here to learn more about Azure Queue Storage.

Figure 6

Give the Queue a name and the Storage account connection which is used for the Function App, as shown in the below figure.

Figure 7

Let’s modify our function based on the changes we made in the output.

  1. public class Order{
  2. public string OrderId{get;set;}
  3. public string ProductId{get;set;}
  4. public string UserEmail{get;set;}
  5. public decimal Price {get;set;}
  6. }
  7. public static async Task<object> Run(HttpRequestMessage req, ILogger log, IAsyncCollector<Order> outputQueueItem)
  8. {
  9. string jsonContent= await req.Content.ReadAsStringAsync();
  10. var myOrder= JsonConvert.DeserializeObject<Order>(jsonContent);
  11. log.LogInformation($"Order {myOrder.OrderId} received from {myOrder.UserEmail} for product{myOrder.ProductId}");
  12. await outputQueueItem.AddAsync(myOrder);
  13. return (object)new OkObjectResult($"Your Order is Placed with Order Id {myOrder.OrderId}, Thank you" );
  14. }

Now, let us listen to the Queue message which contains the incoming order details and create an invoice.

Just go to the "Integrate" window, click on Azure Queue Storage from outputs. In the bottom of the window, you can see the Actions option which says to create a new function triggered by its output. Click on "Go".


Figure 8

Give the function a name, as GenerateInvoice; give the queue a name and storage account which is used while creating the Azure Queue Storage output for the HTTP trigger, as shown in the below figure.

Figure 9

Click "Create". It will generate a function which will display the message in a log available in the Queue, as shown below.

  1. using System;
  2. public class Order{
  3. public string OrderId{get;set;}
  4. public string ProductId{get;set;}
  5. public string UserEmail{get;set;}
  6. public decimal Price {get;set;}
  7. }
  9. public static void Run(Order myQueueItem, ILogger log)
  10. {
  11. log.LogInformation($"{myQueueItem}");
  12. }


Figure 10

  • Go to your Azure function App.
  • Under our GenerateInvoice function, let's click on "Monitor". You can see the application insights.
  • If you have not created it yet, click on "Create an Application Insight for the Function App".

Figure 11

From the application insight, you can see the history of invocation. If we click on the recent log, we can see the order details, which means we have successfully deserialized the JSON payload.

Conclusion


We have seen how to modify an Azure Function by deserializing the JSON payload using the portal and integrate it with Azure Queue Storage service. In my next article, we will see how to integrate an Azure Function with Blob by generating the invoice and storing it in a blob.