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Exercise - Identify a queue

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Let's create a client application to work with a queue. Then, we can add our connection string to the code, create a QueueClient object and create the queue.

Note

You can create the client application on your local computer if you have .NET Core installed, or directly in the Cloud Shell environment.

Clone and open the starter application

In this unit, you build a console application to interact with an Azure storage queue to send and receive messages. The GitHub repository associated with this module contains a starter version of the application that you're building.

1. Start by cloning the solution. In Azure Cloud Shell, run the following command.

   cd ~
   git clone https://github.com/MicrosoftDocs/mslearn-communicate-with-storage-queues.git
   

2. Next, change directories into the starter folder, and open Cloud Shell editor.

   cd ~/mslearn-communicate-with-storage-queues/start
   code .
   

Azure.Storage.Queues NuGet package

To access storage queues from a .NET application, the Azure SDK for .NET provides the Azure.Storage.Queues package on NuGet.

The Azure.Storage.Queues package is already installed in the starter application. To use Azure Storage Queues from one of your applications, install this package from NuGet.

Get your connection string

Your application needs a connection string to be able to connect to your storage queue in Azure. The connection string is available in the Azure portal under the Security+networking > Access keys section of the storage account summary page or it can be retrieved using the Azure CLI or Azure PowerShell.

The following code uses the Azure CLI to retrieve the storage connection string and place it in an environment variable. The application reads this environment variable to get the connection string and connect to the storage queue. Be sure to substitute in the name of your storage account in the following command.

export MY_STORAGE_CONNECTION_STRING=`az storage account show-connection-string -g <rgn>[sandbox resource group name]</rgn> --output tsv -n <storage account name>`

You can verify that you have a connection string set in your environment variable by running the following command to view the connection string:

echo $MY_STORAGE_CONNECTION_STRING

Add code to create a QueueClient

The QueueClient class manages the interactions with a storage queue. The QueueClient class can be used to create a queue and to send and receive messages from the queue.

To create a QueueClient object, you need both the storage connection string and the name of the queue your application uses. In this sample application, the connection string is read from an environment variable.

1. Type code . in the terminal to open the online code editor. Alternatively, if you're working on your own you can use the IDE of your choice.

2. Open the Program.cs file in your code editor.

3. At the beginning of the main method, add the following code.

   string connectionString = Environment.GetEnvironmentVariable("MY_STORAGE_CONNECTION_STRING");
   QueueClient queueClient = new QueueClient(connectionString, "newsqueue");
   

Create your storage account queue

Before you can send or receive messages from your queue, you need to create the queue itself. The queue can be created from the Azure portal, Azure CLI, Azure PowerShell or in code. For our example application, we're going to create the queue from code.

The CreateIfNotExistsAsync method on the QueueClient class is used to create a queue. This method first checks to see if the named queue for the QueueClient object exists and if not, creates it.

Add the following line of code to the main method of your Program.cs file just after the line that creates the QueueClient object. The QueueClient contains a method CreateIfNotExistsAsync.

await queueClient.CreateIfNotExistsAsync();

The full main method should now look like this example:

static async Task Main(string[] args)
{
    // Add code to create QueueClient and Storage Queue Here
    string connectionString = Environment.GetEnvironmentVariable("MY_STORAGE_CONNECTION_STRING");
    QueueClient queueClient = new QueueClient(connectionString, "newsqueue");
    await queueClient.CreateIfNotExistsAsync();

    bool exitProgram = false;
    while (exitProgram == false)
    {
        Console.WriteLine("What operation would you like to perform?");
        Console.WriteLine("  1 - Send message");
        Console.WriteLine("  2 - Peek at the next message");
        Console.WriteLine("  3 - Receive message");
        Console.WriteLine("  X - Exit program");

        ConsoleKeyInfo option = Console.ReadKey();
        Console.WriteLine();  // ReadKey does not got the the next line, so this does
        Console.WriteLine();  // Provide some whitespace between the menu and the action

        if (option.KeyChar == '1')
            await SendMessageAsync(queueClient);
        else if (option.KeyChar == '2')
            await PeekMessageAsync(queueClient);
        else if (option.KeyChar == '3')
            await ReceiveMessageAsync(queueClient);
        else if (option.KeyChar == 'X')
            exitProgram = true;
        else
            Console.WriteLine("invalid choice");
    }
}

Now that the application is connecting to Azure and creating a storage queue, we can work on implementing code to send and receive messages from the queue.

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