PlainBytes.Mediation

YAMI (Yet another mediator implementation). Opinionated Mediator implementation to serve the authors needs. With the aim to keep it free and open-source.

Getting Started

Installation

Add the NuGet package to your project (replace with actual package name if published):

dotnet add package PlainBytes.Mediation.Mediator

Usage

1. Setup Dependency Injection and Mediator

var services = new ServiceCollection();
services.AddMediator();

2. Register Handlers

Register your command, query, and notification handlers:

services.AddTransient<IRequestHandler<CreateUserCommand>, CreateUserCommandHandler>();
services.AddTransient<IRequestHandler<CreateUserWithIdCommand, int>, CreateUserWithIdCommandHandler>();
services.AddTransient<IRequestHandler<GetUserNameQuery, string>, GetUserNameQueryHandler>();
services.AddTransient<IRequestHandler<FailingQuery, string>, FailingQueryHandler>();
services.AddTransient<INotificationHandler<UserCreatedNotification>, SendToastNotificationHandler>();
services.AddTransient<INotificationHandler<UserCreatedNotification>, SendWelcomeEmailNotificationHandler>();

3. Build Service Provider and Get Mediator

var provider = services.BuildServiceProvider();
var mediator = provider.GetRequiredService<IMediator>();

4. Example Usages

Send a command (no return value):

await mediator.Send(new CreateUserCommand { UserName = "Alice" });

Send a command (with return value):

var userId = await mediator.Send(new CreateUserWithIdCommand { UserName = "Bob" });
Console.WriteLine($"Returned user id: {userId}");

Execute a query:

var userName = await mediator.Get(new GetUserNameQuery { UserId = userId });
Console.WriteLine($"Fetched user name: {userName}");

Publish a notification:

await mediator.Publish(new UserCreatedNotification { UserName = userName });

5. RequestResult Examples

TrySend and TryGet return a RequestResult:

var nameResult = await mediator.TrySend(new CreateUserCommand { UserName = "Charlie" });
Console.WriteLine($"TrySend result: {nameResult}");

var idResult = await mediator.TrySend(new CreateUserWithIdCommand { UserName = "Diana" });
Console.WriteLine($"TrySend result: {idResult}");

var userNameResult = await mediator.TryGet(new GetUserNameQuery { UserId = 42 });
Console.WriteLine($"TryGet result: {userNameResult}");

var failedResult = await mediator.TryGet(new FailingQuery());
Console.WriteLine($"TryGet failed result: {failedResult}");

6. Adding Logging Pipeline Behaviors

You can enable built-in logging behaviors for requests and notifications. These behaviors use Microsoft.Extensions.Logging.

// Basic exception logging for requests & notifications
services.AddLoggingPipelineBehaviors();

The basic logging behaviors log errors when a request handler or notification handler throws. For additional performance timing (logs successful completion time and failures):

// Logs execution time and errors for requests, and errors for notifications
services.AddPerformanceLoggingPipelineBehaviors();

Choose only one of AddLoggingPipelineBehaviors or AddPerformanceLoggingPipelineBehaviors depending on whether you want timing information.

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For more examples, see the SampleApp/Program.cs file in this repository.

Benchmarks

Can be found in the benchmarks project, while highly depends on hardware here is a set of results for example:

BenchmarkDotNet v0.14.0, Ubuntu 24.04.3 LTS (Noble Numbat) AMD Ryzen 9 5900X, 1 CPU, 24 logical and 12 physical cores .NET SDK 9.0.110 [Host] : .NET 9.0.9 (9.0.925.41916), X64 RyuJIT AVX2 DefaultJob : .NET 9.0.9 (9.0.925.41916), X64 RyuJIT AVX2

Commands and queries

All handlers are registered as transients.

Single and multiple execution of the same command, queries.

Method	Mean	Error	StdDev	Gen0	Allocated
Send_Command	99.35 ns	1.949 ns	1.823 ns	0.0076	128 B
Get_Query	109.20 ns	0.532 ns	0.472 ns	0.0076	128 B
Send_Command_1K	82,010.86 ns	411.569 ns	364.846 ns	7.5684	128000 B
Get_Query_1K	89,398.72 ns	243.521 ns	203.351 ns	7.5684	128000 B

Notifications

All handlers are registered as transients.

1K notifications executed by the different strategies with 3 handlers, there is no work done, thus parallel executions overhead is visible as expected.

Method	Mean	Error	StdDev	Gen0	Allocated
Publish_DefaultStrategy_MultipleHandlers	171.7 us	0.50 us	0.44 us	15.6250	257.81 KB
Publish_StrategicNotifications_Synchronous	200.3 us	0.33 us	0.29 us	15.6250	257.81 KB
Publish_StrategicNotifications_Parallel	243.6 us	0.83 us	0.74 us	32.4707	531.25 KB