Franz.Common.Mediator 1.3.0

Franz.Common.Mediator

Franz.Common.Mediator is the core mediator library for the Franz framework. It provides request/response handling, notifications, and pipeline behaviors, fully decoupled from business models and infrastructure.

📂 Project Structure

Franz.Common/
 ├── Franz.Common.Business/         # Domain models, ValueObjects, Commands, Queries
 ├── Franz.Common.Mediator/         # Mediator abstractions, dispatcher, pipelines, handlers
 │    ├── Messages/                 # ICommand, IQuery, INotification definitions
 │    ├── Handlers/                 # ICommandHandler, IQueryHandler, INotificationHandler
 │    ├── Pipelines/                # IPipeline and custom pipeline behaviors
 │    └── Dispatchers/              # Dispatcher implementing Send/Publish
 ├── Franz.Common.Infrastructure/   # Handler implementations, database or messaging integrations
 └── Franz.Common.Tests/            # Unit tests for Business and Mediator layers

⚡ Usage

1. Define Commands and Queries (Business Layer)

using Franz.Common.Mediator.Messages;

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

public record GetUserQuery(Guid Id) : IQuery<User>;

2. Implement Handlers (Infrastructure Layer)

using Franz.Common.Mediator.Handlers;
using Franz.Common.Business.Domain;

public class CreateUserHandler : ICommandHandler<CreateUserCommand, Guid>
{
    private readonly IUserRepository _repository;

    public CreateUserHandler(IUserRepository repository)
        => _repository = repository;

    public async Task<Guid> Handle(CreateUserCommand request, CancellationToken cancellationToken)
    {
        var user = new User(request.Name, request.Email);
        await _repository.AddAsync(user);
        return user.Id;
    }
}

public class GetUserHandler : IQueryHandler<GetUserQuery, User>
{
    private readonly IUserRepository _repository;

    public GetUserHandler(IUserRepository repository)
        => _repository = repository;

    public Task<User> Handle(GetUserQuery request, CancellationToken cancellationToken)
        => _repository.GetByIdAsync(request.Id);
}

3. Register Mediator in DI Container

using Microsoft.Extensions.DependencyInjection;
using Franz.Common.Mediator;

var services = new ServiceCollection();

services
    .AddMediator(typeof(Dispatcher).Assembly)   // Registers pipelines and handlers
    .AddDependencies();                          // Add business and infrastructure dependencies

4. Send Commands and Queries

var dispatcher = serviceProvider.GetRequiredService<IDispatcher>();

// Send a command
var userId = await dispatcher.Send(new CreateUserCommand("Alice", "alice@example.com"));

// Send a query
var user = await dispatcher.Send(new GetUserQuery(userId));

🧩 Pipeline Behaviors

Custom behaviors can be applied globally:

using Franz.Common.Mediator.Pipelines;
using Franz.Common.EntityFramework.Behaviors;

services.AddTransient(typeof(IPipeline<,>), typeof(PersistenceBehavior<,>));
services.AddTransient(typeof(IPipeline<,>), typeof(LoggingBehavior<,>));
services.AddTransient(typeof(IPipeline<,>), typeof(ValidationBehavior<,>));

📢 Notifications (Integration Events)

using Franz.Common.Mediator.Messages;

public record UserCreatedEvent(User User) : INotification;

public class UserCreatedHandler : INotificationHandler<UserCreatedEvent>
{
    public Task Handle(UserCreatedEvent notification, CancellationToken cancellationToken)
    {
        Console.WriteLine($"User created: {notification.User.Id}");
        return Task.CompletedTask;
    }
}

// Publishing a notification
await dispatcher.Publish(new UserCreatedEvent(user));

🧪 Unit Tests

All existing unit tests in Franz.Common.Business.Tests and Franz.Common.Mediator.Tests ensure value objects, commands/queries, and notifications behave correctly:

[Fact]
public void Copy_SameValueObjectAfter_ReturnsTrue()
{
    var addresseCopie = AddresseUnique.GetCopy();
    Assert.True(addresseCopie.Equals(AddresseUnique));
}

Run all tests:

dotnet test

🔧 Integration

• Dispatcher resolves handlers from DI automatically.
• Pipelines (logging, validation, persistence) are fully pluggable.
• Supports commands, queries, and notifications in a clean separation of concerns.
• Independent of MediatR — Franz.Common.Mediator is the authoritative mediator layer.

📜 License

MIT

flowchart TD
    subgraph Business
        A[Commands / Queries / Events] -->|Send / Publish| B[Dispatcher / IDispatcher]
    end

    subgraph Mediator
        B --> C[Pipeline Behaviors]
        C --> D[Handler Resolution]
    end

    subgraph Infrastructure
        D --> E[Command / Query Handler Implementations]
        D --> F[Notification Handlers / Integration Events]
        E --> G[Repositories / Database / External Services]
        F --> H[Messaging / Event Publishing]
    end

    style Business fill:#f9f,stroke:#333,stroke-width:1px
    style Mediator fill:#9cf,stroke:#333,stroke-width:1px
    style Infrastructure fill:#fc9,stroke:#333,stroke-width:1px

📈 Changelog

Version 1.3

• Upgraded to .NET 9.0.8
• Added new features and improvements
• Separated business concepts from mediator concepts
• Now compatible with both the in-house mediator and MediatR