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Building and Deploying Azure Functions in .NET

Using Queue Triggers

Learn how to apply a storage queue trigger in Azure Functions.

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 ...