Run continuous/triggered task with WebJobs in Azure (part 2)

Now that we have our Storage and Access Keys let’s create a WebJob that will be triggered by the message in Azure Queue. First, let’s create one queue container. The best thing about queue container is that you can put any message you want into the container. In our example, we will use JSON as a message and we will add a list of objects into the container.

Let’s think for a second on a WebJob in our previous example “Run continuous or triggered background task with WebJobs in Azure (part 1)”. What if we want to put a message from this WebJob into Queue and trigger by this event the second WebJob. How could we achieve this? First, you will need to include Microsoft.WindowsAzure.Storage reference into your existing WebJob. We will create a method that will accept a collection of FxRate object (this can be your type of object) and it will push the message to a queue.

How to create a queue triggered Web Job?

As you can see, message is pushed to a queue by simply serializing an object into JSON and creating CloudQueueMessage object and adding this message to queue.
//Push message to queue
var queueMessage = new CloudQueueMessage(JsonConvert.SerializeObject(entity));
queue.AddMessage(queueMessage);

Now that we have changed our first WebJob so that he will create a message and put it into queue let’s create a new WebJob:

Now that we have our template we will use generated Main method body and we will add additional method in Functions class

You maybe ask yourself what does the: “Please set the following connection strings in app.config for this WebJob to run: AzureWebJobsDashboard and AzureWebJobsStorage” means? For running WebJobs on Azure, you need to have Storage Account service. This is used for two reasons:

1. Azure Storage is a data component extension to your Azure Storage for triggered operations with queue, blobs or tables (NoSQL)
2. WebJobs is using Storage Account for storing logs.

Go to the Storage Account you’ve created earlier and go to the Manage Access Keys section and take the connection string and use them in your WebJob. You can use the same Azure Storage account for both connection strings.
Now that we add the keys we can create our QueueFunction method inside of a Functions class:

As you can see the important part of the function is in the first parameter:
[QueueTrigger(“fxrates”)] FXRatesInformation fxInfo

You have specified that you will be using Queue as a trigger and particular fxrates (the name of your queue container) and set FXRatesInformation as a message. This is how this object looks like:

As you see this is a plan .NET class and if you remember from the beginning we have serialized the same object in Continuous running WebJob into JSON. The beauty is that we didn’t have to deserialize the JSON into object again, the WebJob did this for us. And this are steps how you can create a queue triggered WebJob. You can use the same principle for blob storage. This is all on introduction of Azure WebJobs. Please check some interesting links below for additional information on Azure Storage and WebJobs:

Azure Storage Documentation
https://docs.microsoft.com/en-us/azure/storage/

Create a file share in Azure Files
https://docs.microsoft.com/en-us/azure/storage/files/storage-how-to-create-file-share

How to use Azure queue storage with the WebJobs SDK
https://github.com/Azure/azure-webjobs-sdk/wiki/Queues#manual

How to Send Email Using SendGrid with Azure
https://docs.microsoft.com/en-us/azure/sendgrid-dotnet-how-to-send-email

Run Background tasks with WebJobs in Azure App Service
https://docs.microsoft.com/en-us/azure/app-service/web-sites-create-web-jobs

Azure WebJob with .Net Core Console Application
http://www.intstrings.com/ramivemula/articles/azure-webjob-with-net-core-console-application/

Introducing Windows Azure WebJobs
https://www.hanselman.com/blog/IntroducingWindowsAzureWebJobs.aspx