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Building and Deploying Azure Functions in .NET

Using Queue Triggers

Explore how to implement and configure Azure Queue Storage triggers and output bindings in .NET Azure Functions. Understand setting up storage connections, placing messages on queues, and processing them with queue triggers to enable efficient serverless message handling.

We'll cover the following...

Functions can be bound to Azure Queue Storage. Azure Queue Storage is a component of the Azure Storage Account. This technology allows us to use a storage account as a message broker, which is a technology that allows separate applications and services to exchange messages. We can place messages on a queue so they can be read by any eligible subscribers.

We can use Azure Functions both to place messages on a queue and read them from a queue. In this lesson, we will cover both of these functionalities. We will do so with the aid of the following interactive playground:

using Microsoft.AspNetCore.Http;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Attributes;
using Microsoft.Extensions.Logging;
using Microsoft.OpenApi.Models;
using Newtonsoft.Json;
using System;
using System.IO;
using System.Net;
using System.Threading.Tasks;

namespace StorageQueueTriggerDemo
{
    public class Functions
    {
        [FunctionName("HttpTrigger")]
        [OpenApiOperation(operationId: "Run", tags: new[] { "message" })]
        [OpenApiParameter(name: "message", In = ParameterLocation.Query, Required = true, Type = typeof(string), Description = "Message to put on the queue")]
        [OpenApiResponseWithBody(statusCode: HttpStatusCode.OK, contentType: "text/plain", bodyType: typeof(string), Description = "HTTP response")]
        [return: Queue("message-queue-demo")]
        public async Task<string> HttpTrigger(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)] HttpRequest req)
        {
            string message = req.Query["message"];

            var requestBody = await new StreamReader(req.Body).ReadToEndAsync();
            dynamic data = JsonConvert.DeserializeObject(requestBody);
            message = message ?? data?.name;

            if (string.IsNullOrWhiteSpace(message))
                return null;

            return message;
        }

        [FunctionName("StorageQueueTrigger")]
        public void Run([QueueTrigger("message-queue-demo", Connection = "AzureWebJobsStorage")] string myQueueItem, ILogger log)
        {
            Console.WriteLine($"C# Queue trigger function processed: {myQueueItem}");
        }
    }
}
Function with a storage queue trigger

Adding the required dependencies

Before we can use Azure Queue Storage bindings in a function, we will need to add the Microsoft.Azure.WebJobs.Extensions.Storage NuGet package. We do so in line 8 of the AzureFunctionApp.csproj ...