Arbiter

Mediator pattern and Command Query Responsibility Segregation (CQRS) implementation in .NET

Library	Package	Description
Arbiter.Mediation		Lightweight and extensible implementation of the Mediator pattern
Arbiter.CommandQuery		Base package for Commands, Queries and Behaviours
Arbiter.CommandQuery.EntityFramework		Entity Framework Core handlers for the base Commands and Queries
Arbiter.CommandQuery.MongoDB		Mongo DB handlers for the base Commands and Queries
Arbiter.CommandQuery.Endpoints		Minimal API endpoints for base Commands and Queries

Arbiter.Mediation

A lightweight and extensible implementation of the Mediator pattern for .NET applications, designed for clean, modular architectures like Vertical Slice Architecture and CQRS.

Mediation Installation

The Arbiter Mediation library is available on nuget.org via package name Arbiter.Mediation.

To install Arbiter Mediation, run the following command in the Package Manager Console

Install-Package Arbiter.Mediation

OR

dotnet add package Arbiter.Mediation

Mediation Features

• Request with response handling using IRequest<TResponse> and IRequestHandler<TRequest, TResponse>
• Notifications (Events) using INotification and INotificationHandler<TNotification>
• Pipeline Behaviors, like middleware, using IPipelineBehavior<TRequest, TResponse>
• Dependence Injection based

Define Request

public class Ping : IRequest<Pong>
{
    public string? Message { get; set; }
}

Implement Handler

public class PingHandler : IRequestHandler<Ping, Pong>
{
    public async ValueTask<Pong> Handle(
        Ping request,
        CancellationToken cancellationToken = default)
    {
        // Simulate some work
        await Task.Delay(100, cancellationToken);

        return new Pong { Message = $"{request.Message} Pong" };
    }
}

Define Pipeline Behavior

public class PingBehavior : IPipelineBehavior<Ping, Pong>
{
    public async ValueTask<Pong> Handle(
        Ping request,
        RequestHandlerDelegate<Pong> next,
        CancellationToken cancellationToken = default)
    {
        // Do something before the request is handled
        var response = await next(cancellationToken);
        // Do something after the request is handled

        return response;
    }
}

Register Handlers

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        // Register Arbiter services
        services.AddArbiter();

        // Register handlers
        services.TryAddTransient<IRequestHandler<Ping, Pong>, PingHandler>();

        // Optionally register pipeline behaviors, supports multiple behaviors
        services.AddTransient<IPipelineBehavior<Ping, Pong>, PingBehavior>();
    }
}

Send Request

public class PingController : ControllerBase
{
    private readonly IMediator _mediator;

    public PingController(IMediator mediator)
    {
        _mediator = mediator;
    }

    [HttpGet]
    public async Task<IActionResult> Get(
        string? message = null,
        CancellationToken? cancellationToken = default)
    {
        var request = new Ping { Message = message };
        var response = await _mediator.Send<Ping, Pong>(request, cancellationToken);

        return Ok(response);
    }
}

Arbiter.CommandQuery

Command Query Responsibility Segregation (CQRS) framework based on mediator pattern

CommandQuery Installation

The Arbiter Command Query library is available on nuget.org via package name Arbiter.CommandQuery.

To install Arbiter Command Query, run the following command in the Package Manager Console

Install-Package Arbiter.CommandQuery

OR

dotnet add package Arbiter.CommandQuery

CommandQuery Features

• Base commands and queries for common CRUD operations
• Generics base handlers for implementing common CRUD operations
• Common behaviors for audit, caching, soft delete, multi-tenant
• View model to data modal mapping
• Entity Framework Core handlers for common CRUD operations
• MongoDB handlers for common CRUD operations

Arbiter.CommandQuery.EntityFramework

Entity Framework Core handlers for the base Commands and Queries

EntityFramework Installation

Install-Package Arbiter.CommandQuery.EntityFramework

OR

dotnet add package Arbiter.CommandQuery.EntityFramework

Arbiter.CommandQuery.MongoDB

Mongo DB handlers for the base Commands and Queries

MongoDB Installation

Install-Package Arbiter.CommandQuery.MongoDB

OR

dotnet add package Arbiter.CommandQuery.MongoDB

Arbiter.CommandQuery.Endpoints

Minimal API endpoints for base Commands and Queries

Endpoints Installation

Install-Package Arbiter.CommandQuery.Endpoints

OR

dotnet add package Arbiter.CommandQuery.Endpoints