Produced and consumed using Apache Kafka

Creating a Kafka event-driven project involves setting up a system where events are produced and consumed using Apache Kafka. Here's a step-by-step guide to help you create a Kafka event-driven project using .NET Core:

Step 1: Set Up Your Development Environment

Install .NET Core SDK: Make sure you have the .NET Core SDK installed. You can download it from the .NET website.
Install Kafka: Download and install Apache Kafka from the Kafka website. Follow the instructions to start the Kafka server and Zookeeper.

Step 2: Create a New .NET Core Project

Open your terminal or command prompt.

Create a new .NET Core Web API project:

 dotnet new webapi -n KafkaEventDrivenProject
 cd KafkaEventDrivenProject

Step 3: Add Required NuGet Packages

Add the necessary NuGet packages for Kafka and SQL Server:

dotnet add package Confluent.Kafka
dotnet add package Microsoft.EntityFrameworkCore.SqlServer
dotnet add package Microsoft.EntityFrameworkCore.Tools

Step 4: Configure SQL Server Database

Create the EventMessage model:

 public class EventMessage
 {
     public int Id { get; set; }
     public string Topic { get; set; }
     public string Message { get; set; }
     public DateTime Timestamp { get; set; }
 }

Create the AppDbContext class:

 using Microsoft.EntityFrameworkCore;

 public class AppDbContext : DbContext
 {
     public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }

     public DbSet<EventMessage> EventMessages { get; set; }
 }

Configure the connection string in appsettings.json:

 {
     "ConnectionStrings": {
         "DefaultConnection": "Server=your_server;Database=your_database;User Id=your_user;Password=your_password;"
     }
 }

Update Startup.cs to add the DbContext:

 public void ConfigureServices(IServiceCollection services)
 {
     services.AddDbContext<AppDbContext>(options =>
         options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
     services.AddControllers();
 }

Step 5: Implement Kafka Producer

Create the KafkaProducer class:

 using Confluent.Kafka;
 using System.Threading.Tasks;

 public class KafkaProducer
 {
     private readonly IProducer<string, string> _producer;
     private readonly string _topic;

     public KafkaProducer(IConfiguration configuration)
     {
         var config = new ProducerConfig { BootstrapServers = configuration["Kafka:BootstrapServers"] };
         _producer = new ProducerBuilder<string, string>(config).Build();
         _topic = configuration["Kafka:Topic"];
     }

     public async Task ProduceAsync(string message)
     {
         await _producer.ProduceAsync(_topic, new Message<string, string> { Value = message });
     }
 }

Step 6: Implement Kafka Consumer

Create the KafkaConsumer class:

 using Confluent.Kafka;
 using System;
 using System.Threading;
 using System.Threading.Tasks;

 public class KafkaConsumer
 {
     private readonly IConsumer<string, string> _consumer;
     private readonly AppDbContext _context;

     public KafkaConsumer(IConfiguration configuration, AppDbContext context)
     {
         var config = new ConsumerConfig
         {
             BootstrapServers = configuration["Kafka:BootstrapServers"],
             GroupId = configuration["Kafka:GroupId"],
             AutoOffsetReset = AutoOffsetReset.Earliest
         };
         _consumer = new ConsumerBuilder<string, string>(config).Build();
         _context = context;
     }

     public void Consume(CancellationToken cancellationToken)
     {
         _consumer.Subscribe(_context.Configuration["Kafka:Topic"]);
         try
         {
             while (true)
             {
                 var consumeResult = _consumer.Consume(cancellationToken);
                 Console.WriteLine($"Consumed message '{consumeResult.Message.Value}' at: '{consumeResult.TopicPartitionOffset}'.");

                 // Save the consumed message to the database
                 var eventMessage = new EventMessage
                 {
                     Topic = consumeResult.Topic,
                     Message = consumeResult.Message.Value,
                     Timestamp = DateTime.UtcNow
                 };
                 _context.EventMessages.Add(eventMessage);
                 _context.SaveChanges();
             }
         }
         catch (OperationCanceledException)
         {
             _consumer.Close();
         }
     }
 }

Step 7: Create API Endpoints

Create the KafkaController class:

 using Microsoft.AspNetCore.Mvc;
 using System.Threading.Tasks;
 using System.Linq;

 [Route("api/[controller]")]
 [ApiController]
 public class KafkaController : ControllerBase
 {
     private readonly KafkaProducer _producer;
     private readonly KafkaConsumer _consumer;
     private readonly AppDbContext _context;

     public KafkaController(KafkaProducer producer, KafkaConsumer consumer, AppDbContext context)
     {
         _producer = producer;
         _consumer = consumer;
         _context = context;
     }

     [HttpPost("publish")]
     public async Task<IActionResult> Publish([FromBody] string message)
     {
         await _producer.ProduceAsync(message);
         return Ok();
     }

     [HttpGet("consume")]
     public IActionResult Consume()
     {
         var cancellationTokenSource = new CancellationTokenSource();
         _consumer.Consume(cancellationTokenSource.Token);
         return Ok();
     }

     [HttpGet("events")]
     public IActionResult GetEvents()
     {
         var events = _context.EventMessages.ToList();
         return Ok(events);
     }

     [HttpGet("events/{id}")]
     public IActionResult GetEventById(int id)
     {
         var eventMessage = _context.EventMessages.Find(id);
         if (eventMessage == null)
         {
             return NotFound();
         }
         return Ok(eventMessage);
     }

     [HttpPut("events/{id}")]
     public IActionResult UpdateEvent(int id, [FromBody] EventMessage updatedEvent)
     {
         var eventMessage = _context.EventMessages.Find(id);
         if (eventMessage == null)
         {
             return NotFound();
         }

         eventMessage.Topic = updatedEvent.Topic;
         eventMessage.Message = updatedEvent.Message;
         eventMessage.Timestamp = updatedEvent.Timestamp;

         _context.EventMessages.Update(eventMessage);
         _context.SaveChanges();

         return NoContent();
     }

     [HttpDelete("events/{id}")]
     public IActionResult DeleteEvent(int id)
     {
         var eventMessage = _context.EventMessages.Find(id);
         if (eventMessage == null)
         {
             return NotFound();
         }

         _context.EventMessages.Remove(eventMessage);
         _context.SaveChanges();

         return NoContent();
     }
 }

Step 8: Run Migrations and Update Database

Run the following commands to create and apply migrations:

dotnet ef migrations add InitialCreate
dotnet ef database update

Step 9: Run the Application

Run the application:

dotnet run

Integrating with Azure

To integrate with Azure, you can use Azure Event Hubs as a Kafka-compatible endpoint. Follow the steps mentioned in the previous response to set up Azure Event Hubs and configure your application to use it.