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Introduction

MediatorK is a coroutine-first Mediator library for Kotlin and Kotlin Multiplatform.

It implements the CQRS and Vertical Slice patterns:

  • Every request is routed to exactly one handler
  • Every notification fans out to many handlers
  • A pipeline of behaviors sits in between (logging, caching, timeout, validation…)

No kotlin-reflect. No annotation processing. No framework required.

Quick Example​

// 1. Define a request
data class GetUserQuery(val id: String) : Request<User>

// 2. Implement a handler
class GetUserHandler(private val db: UserRepository) : RequestHandler<GetUserQuery, User> {
    override suspend fun handle(
        mediator: Mediator,
        requestContext: RequestContext,
        request: GetUserQuery
    ): User = db.findById(request.id) ?: error("User not found")
}

// 3. Wire it up
val mediator = MediatorFactory.create(
    registrars = listOf(object : MediatorRegistrar {
        override fun register(registry: HandlerRegistry) {
            registry register GetUserHandler(db)
        }
    })
)

// 4. Use it
val user = mediator.send(GetUserQuery("user-1"))

Ready to start? See the promise MediatorK makes →