Project Documentation: Order Creation, Payment, and Notification with MassTransit and RabbitMQ in .NET Core, Docker

Overview

This project demonstrates the integration of MassTransit and RabbitMQ in a .NET Core application to manage order creation, payment processing, and sending SMS and email notifications. The system involves multiple services working together to simulate a real-world order processing and notification flow. RabbitMQ, running in a Docker container, is used for message queuing, ensuring decoupled communication between services. MassTransit is employed to simplify message-based communication and to manage the message-driven workflows.

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Key Components

1. Order Service - Responsible for receiving and processing new orders.
2. Payment Service - Handles payment processing after an order is placed.
3. Notification Service - Sends email and SMS notifications once the payment is confirmed.

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Architecture

The architecture follows a microservices approach, where each service is responsible for a distinct part of the workflow:

• Order Service: Initiates the order and communicates with the Payment Service to process the payment.
• Payment Service: Receives payment details, processes the payment, and triggers notifications upon successful payment.
• Notification Service: Sends SMS and email notifications.

MassTransit is used for asynchronous communication between these services via RabbitMQ as the message broker.

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Technologies Used

• MassTransit: A .NET-based service bus for building message-based applications.
• RabbitMQ: A message broker that handles the transmission of messages between services.
• .NET Core: Framework used to build the application and the individual services.
• Docker: Application management in a container-based environment.

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Workflow

1. Order Creation:

   • The user places an order, which is captured by the Order Service.
   • A message is sent to the Payment Service to process the payment. The message includes order details and payment information.

2. Payment Processing:

   • The Payment Service receives the order and payment details.
   • The payment is processed (e.g., payment gateway integration).
   • Upon successful payment, a message is sent to the Notification Service to trigger the SMS and email notifications.

3. Notification Sending:

   • The Notification Service receives the payment success message and sends SMS and email notifications to the customer, confirming the successful order and payment.

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MassTransit & RabbitMQ Integration

1. Setting up RabbitMQ:

   • RabbitMQ is configured to manage queues for each service communication. Separate queues are set for orders, payments, and notifications.
   • Services subscribe to their respective queues to listen for incoming messages.

2. MassTransit Configuration:

   • MassTransit is integrated with RabbitMQ to handle the asynchronous communication.
   • The ISendEndpoint and IReceiveEndpoint interfaces are used to send and receive messages between the services.

   Example of configuration in Program.cs:

   builder.Services.Configure<MassTransitSettings>(builder.Configuration.GetSection("MassTransitSettings"));
   builder.Services.AddMassTransit(x =>
   {
    x.RegisterConsumer<OrderPaymentReceivedEventConsumers>();
    x.UsingRabbitMq((context, cfg) =>
    {
        var massTransitSettings = context.GetRequiredService<IOptions<MassTransitSettings>>().Value;
        cfg.Host(massTransitSettings.Host, massTransitSettings.VirtualHost, host =>
        {
            host.Username(massTransitSettings.Username);
            host.Password(massTransitSettings.Password);
        });
       cfg.RegisterQueue<OrderPaymentReceivedEventConsumers>(context, massTransitSettings.QueueName, typeof(OrderPaymentReceivedEvent));
    });
   });

RabbitMQ Installation with Docker

1. Download and install Docker on your computer from: Docker Desktop

2. To install RabbitMQ with Docker, use the following command:

docker run -d --name rabbitmq -p 5672:5672 -p 15672:15672 rabbitmq:3-management