Baobab.SharedKernel.Presentation 1.0.0

Baobab SharedKernel

A Clean Architecture / Domain-Driven Design foundation for .NET applications of any shape — microservices, modular monoliths, or a single well-organized service. CQRS, an assembly-aware OutBox pattern, comprehensive auditing, and a Result-based error-handling model, all wired together so you can start on business logic instead of infrastructure plumbing, whatever your deployment topology ends up being.

This isn't a scaffold of interfaces waiting to be implemented — every layer below is a working implementation you can reference, extend, or drop into a project today.

Why this exists

Most "Clean Architecture starter" repos give you folder names and a few marker interfaces. This gives you the parts that are actually tedious to get right: an OutBox implementation that won't double-process events when two services share a database, an audit trail that distinguishes background jobs from user requests, a Result type hierarchy that composes across validation and pagination, and Guid generation that stays sortable in the database instead of fragmenting your indexes.

Architecture

SharedKernel/
├── Baobab.SharedKernel.Domain          Entities, aggregates, value objects,
│                                       domain events, the Result pattern
├── Baobab.SharedKernel.Application     CQRS (ICommand/IQuery), pipeline
│                                       behaviors, service abstractions
├── Baobab.SharedKernel.Persistence     EF Core, OutBox pattern, audit
│                                       trail, specifications, unit of work
├── Baobab.SharedKernel.Infrastructure  Caching, background jobs, messaging,
│                                       resilience, external services
└── Baobab.SharedKernel.Presentation    API controllers, Minimal APIs,
                                        exception handling, versioning

Dependencies point inward only: Presentation -> Infrastructure -> Persistence -> Application -> Domain. The Domain layer has zero project dependencies.

What's implemented

• Domain-Driven Design primitives — AggregateRoot, Entity, EntityExtra (audit fields), ValueObject, with rich value objects (Money, EmailAddress, PhoneNumber, GhanaCardPersonalIdentificationNumber)
• CQRS — ICommand/IQuery interfaces over MediatR, with ValidationPipelineBehavior (FluentValidation → Result), LoggingPipelineBehavior, and UnitOfWorkPipelineBehavior running in sequence on every request
• Result pattern — Result, ResultT<T>, ValidationResult, PaginatedResult<T> in place of exceptions for expected business outcomes
• Assembly-aware OutBox pattern — domain events are captured in the same transaction as your data, then published by a background job. The ExecutingAssembly field means multiple services sharing one database only ever process their own events. Idempotent handler decoration means a retried message doesn't re-run side effects.
• Guid v7 identifiers — every ID is a Guid created via Guid.CreateVersion7(): sortable and time-ordered like a ULID, but a native .NET type with no third-party dependency
• Audit trail — AuditableContext<T> captures before/after values, the acting user, and timestamps automatically on every SaveChangesAsync, with explicit handling for background jobs running without a user context
• Specification pattern — HeroSpecification<T> for composable, reusable query logic with includes and ordering
• Multi-strategy caching — Redis-backed and in-memory implementations of the same ICacheManager interface
• Background jobs — Hangfire integration with Polly retry policies
• Messaging — MassTransit + RabbitMQ for integration events
• Notifications — email (Amazon SES or SMTP), SMS, and push, each with a sync path and a MassTransit-published integration-event path
• File storage — AWS S3 upload/download behind IAmazonSimpleStorageService
• API security — JWT bearer authentication, multi-factor API key/secret generation, zone-based authorization layered on top of role checks
• Observability — OpenTelemetry tracing/metrics across ASP.NET Core, EF Core, Hangfire, gRPC, and Redis, plus Sentry (or self-hosted GlitchTip) error tracking correlated to the same traces
• Presentation extras — API versioning (controllers and Minimal APIs), Swagger with JWT bearer auth wired in, rate limiting, and an RFC 7807 global exception handler

Getting Started

git clone https://github.com/barimahyaw/baobab.git
cd baobab
dotnet restore Baobab.sln
dotnet build Baobab.sln

NuGet packages aren't published yet — for now, reference the projects directly or pull the SharedKernel/ folder into your solution. See docs/getting-started.md for a full walkthrough of building a service on top of this foundation.

A taste of the patterns

Rich domain model, raising an event:

public class Order : AggregateRoot
{
    public Result AddItem(ProductId productId, Money unitPrice, int quantity)
    {
        if (Status != OrderStatus.Draft)
            return Result.Fail(Errors.OrderErrors.CannotModifyConfirmedOrder);

        var item = OrderItem.Create(Guid.CreateVersion7(), productId, unitPrice, quantity);
        _items.Add(item);

        RaiseDomainEvent(new OrderItemAddedDomainEvent(Id, productId, quantity));
        return Result.Success();
    }
}

CQRS command handler, Result all the way down:

public record CreateUserCommand(string Email, string FirstName) : ICommand<Guid>;

public class CreateUserCommandHandler(AppDbContext dbContext) : ICommandHandler<CreateUserCommand, Guid>
{
    public async Task<IResult<Guid>> Handle(CreateUserCommand request, CancellationToken cancellationToken)
    {
        var emailResult = EmailAddress.Validate(request.Email);
        if (!emailResult.Succeeded) return ResultT<Guid>.Fail(emailResult.Messages);

        var user = User.Create(EmailAddress.Create(request.Email), request.FirstName);
        await dbContext.Users.AddAsync(user, cancellationToken);
        // UnitOfWorkPipelineBehavior calls SaveChangesAsync after the handler returns

        return ResultT<Guid>.Success(user.Id);
    }
}

Minimal API controller:

[ApiVersion("1.0")]
public class UsersController : BaseApiController<UsersController>
{
    [HttpPost]
    public async Task<IActionResult> CreateUser([FromBody] CreateUserCommand command)
    {
        var result = await Mediator.Send(command);
        return result.Succeeded
            ? CreatedAtAction(nameof(GetUser), new { id = result.Value }, result.Value)
            : BadRequest(result.Messages);
    }
}

Documentation

Project Status

This is an actively evolving personal project — the core is stable and used as the foundation for real services, but public NuGet packages and a templated dotnet new experience aren't published yet. Track progress in CHANGELOG.md.

Contributing

Bug reports, documentation fixes, and code contributions are welcome — see CONTRIBUTING.md.

Security

See SECURITY.md for how to report a vulnerability.

License

MIT — see LICENSE.