QsMessaging-develop 1.0.232-pr

QsMessaging

QsMessaging is a .NET 8 library designed for sending and receiving messages between services or components of your application using RabbitMQ. It supports horizontal scalability, allowing multiple instances of the same service to handle messages efficiently.
Available on NuGet for seamless integration:

A simple, scalable messaging solution for distributed systems.

Installation

Install the package using the following command:

dotnet add package QsMessaging

Registering the Library

Registering the library is simple. Add the following two lines of code to your Program.cs:

// Add QsMessaging (use the default configuration)...
builder.Services.AddQsMessaging(options => { });

...
await host.UseQsMessaging();

Default Configuration

RabbitMQ

• Host: localhost
• UserName: guest
• Password: guest
• Port: 5672

Usage

Sending Messages

Contract

Define a message contract:

public class RegularMessageContract
{
    public required string MyTextMessage { get; set; }
}

Sending a Message

Inject IQsMessaging into your class:

public YourClass(IQsMessaging qsMessaging) {}

Then, use it to send a message:

await qsMessaging.SendMessageAsync(new RegularMessageContract { MyTextMessage = "My message." });

Handling Messages

To handle the message, create a handler:

public class RegularMessageContractHandler : IQsMessageHandler<RegularMessageContract>
{
    public Task<bool> Consumer(RegularMessageContract contractModel)
    {
        // Process the message here
        return Task.FromResult(true);
    }
}

All handlers discovered by QsMessaging are registered in DI as Transient. This means each message/request is handled by a fresh handler instance, and handlers have full support for constructor injection of your application services.

Request/Response Pattern

You can also use the Request/Response pattern to send a request and await a response. This is useful when you need to communicate between services and expect a response.

Request/Response Contract

Define the request and response contracts:

public class MyRequestContract
{
    public required string RequestMessage { get; set; }
}

public class MyResponseContract
{
    public required string ResponseMessage { get; set; }
}

Sending a Request and Receiving a Response

To send a request and await a response, use the RequestResponse<TRequest, TResponse>:

public class MyService
{
    private readonly IQsMessaging _qsMessaging;

    public MyService(IQsMessaging qsMessaging)
    {
        _qsMessaging = qsMessaging;
    }

    public async Task<MyResponseContract> SendRequestAsync(MyRequestContract request)
    {
        var response = await _qsMessaging.SendRequestResponseAsync<MyRequestContract, MyResponseContract>(request);
        return response;
    }
}

Handling Requests

To handle requests, implement the IQsRequestResponseHandler<TRequest, TResponse> interface:

public class MyRequestHandler : IQsRequestResponseHandler<MyRequestContract, MyResponseContract>
{
    public Task<MyResponseContract> Handle(MyRequestContract request)
    {
        // Process the request and create a response
        return Task.FromResult(new MyResponseContract { ResponseMessage = "Response to: " + request.RequestMessage });
    }
}

That's all, folks!

Documentation

For detailed documentation, visit the QsMessaging Wiki.

Dependency Injection Examples

The examples below show how handlers can consume dependencies through constructor injection.

1) Message Handler with Injected Services

public interface IOrderProcessor
{
    Task ProcessAsync(CreateOrderMessage message);
}

public class CreateOrderMessage
{
    public required string OrderId { get; set; }
}

public class CreateOrderMessageHandler : IQsMessageHandler<CreateOrderMessage>
{
    private readonly IOrderProcessor _orderProcessor;
    private readonly ILogger<CreateOrderMessageHandler> _logger;

    public CreateOrderMessageHandler(
        IOrderProcessor orderProcessor,
        ILogger<CreateOrderMessageHandler> logger)
    {
        _orderProcessor = orderProcessor;
        _logger = logger;
    }

    public async Task<bool> Consumer(CreateOrderMessage contractModel)
    {
        _logger.LogInformation("Processing order {OrderId}", contractModel.OrderId);
        await _orderProcessor.ProcessAsync(contractModel);
        return true;
    }
}

2) Request/Response Handler with Injected Repository

public interface IUserRepository
{
    Task<UserDto?> GetByIdAsync(Guid id);
}

public class GetUserRequest
{
    public Guid UserId { get; set; }
}

public class GetUserResponse
{
    public string? Name { get; set; }
    public bool Found { get; set; }
}

public class GetUserHandler : IQsRequestResponseHandler<GetUserRequest, GetUserResponse>
{
    private readonly IUserRepository _userRepository;

    public GetUserHandler(IUserRepository userRepository)
    {
        _userRepository = userRepository;
    }

    public async Task<GetUserResponse> Handle(GetUserRequest request)
    {
        var user = await _userRepository.GetByIdAsync(request.UserId);
        return new GetUserResponse
        {
            Found = user is not null,
            Name = user?.Name
        };
    }
}