Install mediator

From current assembly

services.AddMediator(mediator => mediator.RegisterPartsFromExecutingAssembly())

From assemblies

services.AddMediator(typeof(Class1).Assembly, typeof(Class2).Assembly)

Register concrete parts

services.AddMediator(typeof(PreProcessor), typeof(Handler))

Other installation options

services.AddMediator(mediator => mediator
     .RegisterNotification<MyNotification>() // register pipeline if parts already registered in ServiceCollection
     .RegisterRequest<MyRequest>() // register pipeline if parts already registered
     .RegisterParts(partTypes) // register mediator parts from array of types
     .RegisterParts(partAssemblies) // register mediator parts from array of assemblies
     .AsSingleton()); // define lifetime if required (default - scoped)

Performance

Method	Mean	Error	StdDev	Ratio	Gen 0	Gen 1	Gen 2	Allocated
MediatR	253.35 us	3.823 us	3.576 us	1.00	48.3398	1.4648	-	298.61 KB
Marble	54.38 us	0.467 us	0.414 us	0.21	4.9438	0.3662	-	30.58 KB