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Sukhpinder Singh
Sukhpinder Singh

Posted on • Originally published at singhsukhpinder.Medium

10-Day .Net Aspire Challenge: Day 5 — Apache Kafka

#kafka #dotnet #csharp #webdev

Step-by-step guide on how to use the .Net Aspire Kafka component in Visual Studio.

Introduction

.Net Aspire framework is used to develop cloud and production-ready distributed applications. It consists of components to handle cloud-native concerns such as Redis, Postgres etc.

Prerequisites

Objectives

Learn how to create a starter project using .Net Aspire with the Apache Kafka component.

Github Sample: The solution structure is divided into the following projects

  • DotnetAspireChallenge.ApiService

  • DotnetAspireChallenge.AppHost

  • DotnetAspireChallenge.ServiceDefaults

  • DotnetAspireChallenge.Web

Getting Started

Step 1: Install the following NuGet package

Install the following Nuget package into the subsequent project “DotnetAspireChallenge.AppHost”

dotnet add package Aspire.Hosting.Kafka
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In the above project, register Kafka UI as shown below

    var messaging = builder.AddKafka("messaging")
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.WithKafkaUI();

Then finally add a reference to both the Producer and Consumer where the producer is “DotnetAspireChallenge.ApiService” and the consumer is “DotnetAspireChallenge.Web” project respectively.

    var apiService = builder.AddProject<Projects.DotnetAspireChallenge_ApiService>("apiservice")
        .WithReference(messaging);



    builder.AddProject<Projects.DotnetAspireChallenge_Web>("webfrontend")
        .WithExternalHttpEndpoints()
        .WithReference(cache)
        .WithReference(apiService)
        .WithReference(messaging);
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Step 2: Add dependency of Kafka Producer

Add the dependency in the Program.cs file of the project “DotnetAspireChallenge.ApiService”

    builder.AddKafkaProducer<string, string>("messaging");
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and add a relevant minimal API endpoint using the following code.

    public static class AspireKafkaExtension
    {
        public static void MapAspireKafkaEndpoint(this WebApplication app)
        {
            app.MapGet("/send", async (IProducer<string, string> services, string key, string value) =>
            {
                try
                {
                    var message = new Message<string, string> { Key = key, Value = value };
                    DeliveryResult<string, string>? result = await services.ProduceAsync("messaging", message);
                    return result;
                }
                catch (Exception ex)
                {

                    throw;
                }

            });
        }
    }
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The endpoint takes two parameters namely key and value as route values, and produces the message on the docker-hosted Kafka server.

https://localhost:7313/send?key=key&value=1
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Step 3: Add dependency of Kafka Consumer

Now move “DotnetAspireChallenge.Web” project wherein register as a Kafka producer

    builder.AddKafkaConsumer<string, string>("messaging", options =>
    {
        options.Config.GroupId = "my-consumer-group";
        options.Config.AutoOffsetReset = AutoOffsetReset.Earliest;
        options.Config.EnableAutoCommit = false;
    });
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*Note: * It's mandatory to provide a default group ID.

Step 4: Create a Razor Page

Create a basic razor page named “KafkaConsumer.razor” to show the consumed message from the Kafka server.

    @page "/kafka"
    @attribute [StreamRendering(true)]
    @attribute [OutputCache(Duration = 5)]
    @using Confluent.Kafka
    <h3>KafkaConsumer</h3>

    @inject KafkaConsumeMessageClient kafaConsumeMessageClient
    <PageTitle>Kafka Consumed Message</PageTitle>

    <h1>Kafka</h1>

    <p>This component demonstrates showing data loaded from a backend API service.</p>

    @if (consumedMessage == null)
    {
        <p><em>Loading...</em></p>
    }
    else
    {
        <table class="table">
            <thead>
                <tr>
                    <th>Topic</th>
                    <th>Value</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td>@consumedMessage.Topic</td>
                    <td>@consumedMessage.Value</td>
                </tr>

            </tbody>
        </table>
    }
    @code {
        private ConsumeResult<string, string>? consumedMessage;

        protected override async Task OnInitializedAsync() => consumedMessage = kafaConsumeMessageClient.GetKafkaMessage();
    }
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Step 5: Configure HttpCall to the ApiService 

    public class KafkaConsumeMessageClient(HttpClient httpClient, IConsumer<string, string> _consumer)
    {

        public ConsumeResult<string, string>? GetKafkaMessage(CancellationToken cancellationToken = default)
        {
            ConsumeResult<string, string>? deliveryResult = null;
            _consumer.Subscribe("messaging");
            deliveryResult = _consumer.Consume(TimeSpan.FromSeconds(10));

            return deliveryResult;
        }
    }
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Kafka Produce Demo

Kafka UI Demo

Kafka Consume Demo

Github Project

GitHub - ssukhpinder/DotnetAspireChallenge: 10 Day .Net Aspire Challenge

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