Zapto.Mediator

Simple mediator implementation for Microsoft.Extensions.DependencyInjection.

This project is inspired by MediatR. It uses MediatR.Contracts so you can reuse all your contracts.

Differences

Zapto.Mediator:

1. Only supports Microsoft.Extensions.DependencyInjection.
2. Requires you to specify types with ISender.Send<TRequest, TResponse>(new TRequest()) to avoid boxing.
   To make it easier you can use Zapto.Mediator.SourceGenerator to generate extension methods (e.g. ISender.RequestAsync()).
3. Allows you to use C# 10 delegates.
4. Allows you to use request namespaces (multiple request handlers under a different namespace).
5. Uses ValueTask instead of Task.
6. Generic support

Benchmark

For more details and more benchmarks, see Benchmarks.md.

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated
MediatR	150.164 ns	0.9268 ns	0.8669 ns	93.97	0.55	0.0243	408 B
Zapto	58.938 ns	0.3907 ns	0.3463 ns	36.88	0.22	0.0043	72 B

Example

using MediatR;
using Zapto.Mediator;
using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
var upperNs = new MediatorNamespace("upper");

services.AddMediator(builder =>
{
    // Add a request handler for "GetMessage"
    builder.AddRequestHandler((GetMessage _) => "Hello world");

    // Add a notification handler for "WriteLineNotification"
    builder.AddNotificationHandler((WriteLineNotification notification) =>
    {
        Console.WriteLine(notification.Message);
    });
});

services.AddMediator(upperNs, builder =>
{
    // Add a notification handler for "WriteLineNotification" with-in the mediator namespace "upper"
    builder.AddNotificationHandler((WriteLineNotification notification) =>
    {
        Console.WriteLine(notification.Message.ToUpper());
    });
});

// Create the service provider and execute the request and notifications
// Note that the extension methods 'GetMessageAsync' and 'WriteLineAsync' are generated by the source generator
await using var provider = services.BuildServiceProvider();

var mediator = provider.GetRequiredService<IMediator>();
var message = await mediator.GetMessageAsync();

await mediator.WriteLineAsync(message);
await mediator.WriteLineAsync(upperNs, message);

public record struct WriteLineNotification(string Message) : INotification;

public record struct GetMessage : IRequest<string>;

Result:

Hello world
HELLO WORLD