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 resolution of handlers and behaviors via scoped IServiceProvider
Supports OpenTelemetry tracing and meters via Arbiter.Mediation.OpenTelemetry
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;
}
}
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
CommandQuery Usage
Register Command Query services via dependency injection
services.AddCommandQuery();
Query By ID
// sample user claims
var principal = new ClaimsPrincipal(new ClaimsIdentity(new[] { new Claim(ClaimTypes.Name, "JohnDoe") }));
var query = new EntityIdentifierQuery<int, ProductReadModel>(principal, 123);
// Send the query to the mediator for execution
var result = await mediator.Send(query);
Query By Filter
var filter = new EntityFilter { Name = "Status", Operator = "eq", Value = "Active" };
var sort = new EntitySort { Name = "Name", Direction = "asc" };
var query = new EntitySelectQuery<ProductReadModel>(principal, filter, sort);
// Send the query to the mediator for execution
var result = await mediator.Send(query);
Update Command
var id = 123; // The ID of the entity to update
var updateModel = new ProductUpdateModel
{
Name = "Updated Product",
Description = "Updated description of the product",
Price = 29.99m
};
var command = new EntityUpdateCommand<int, ProductUpdateModel, ProductReadModel>(principal, id, updateModel);
// Send the command to the mediator for execution
var result = await mediator.Send(command);
Arbiter.CommandQuery.EntityFramework
Entity Framework Core handlers for the base Commands and Queries
