API Reference

Quick reference for all public types in com.fajrbahr.mediatork.

Subpackage	Contents
`com.fajrbahr.mediatork`	Core: `Mediator`, `Request`, `StreamRequest`, `HandlerRegistry`, `MediatorFactory`, `MediatorException` hierarchy
`com.fajrbahr.mediatork.handler`	`RequestHandler`, `StreamRequestHandler`, `FallbackRequestHandler` (`otherwise`), `Sender`, `trySend`
`com.fajrbahr.mediatork.notification`	`Notification`, `NotificationHandler`, `FallbackNotificationHandler` (`otherwise`), all publisher implementations, `ThrowMissingNotificationHandler`, `SilentMissingNotificationHandler`
`com.fajrbahr.mediatork.pipeline`	`PipelineBehavior`, `Stage`, `StreamPipelineBehavior` and all built-in behaviors (logging, caching, timeout, timing, error tracking, request counter)
`com.fajrbahr.mediatork.validator`	`RequestValidator`, `ValidationBehavior`, `ValidationResult`, `ValidationException`, `rules`, `rulesFailFast`

Core interfaces

`Request<out TResponse>`

Marker interface for requests. Implement to declare a message that expects exactly one handler.

interface Request<out TResponse>

Nested type:
Request.Unit — convenience marker for commands that return no value. Equivalent to Request<Unit>.

`RequestHandler<TRequest, TResult>` · `com.fajrbahr.mediatork.handler`

Handles a specific Request type.

interface RequestHandler<in TRequest : Request<TResult>, TResult> {
    suspend fun handle(mediator: Mediator, requestContext: RequestContext, request: TRequest): TResult
}

`StreamRequest<T>`

Marker interface for requests that return a lazy Flow<T> instead of a single value. Dispatch via Mediator.stream().

interface StreamRequest<out T>

Use when the response is a sequence produced over time — large result sets, live feeds, cursor-based exports, or anything better consumed incrementally than batched into a list.

`StreamRequestHandler<TRequest, T>` · `com.fajrbahr.mediatork.handler`

Handles a StreamRequest and returns a cold Flow<T>. The interface is not suspend — it returns the flow immediately; work begins when the caller collects it.

interface StreamRequestHandler<in TRequest : StreamRequest<T>, T> {
    fun handle(mediator: Mediator, requestContext: RequestContext, request: TRequest): Flow<T>
}

// Define
data class StreamInvoicesQuery(val status: InvoiceStatus? = null) : StreamRequest<Invoice>

// Handle
class StreamInvoicesHandler(private val repo: InvoiceRepository)
    : StreamRequestHandler<StreamInvoicesQuery, Invoice> {
    override fun handle(mediator: Mediator, requestContext: RequestContext, request: StreamInvoicesQuery): Flow<Invoice> =
        repo.all().asFlow().let { flow ->
            if (request.status != null) flow.filter { it.status == request.status } else flow
        }
}

// Dispatch
mediator.stream(StreamInvoicesQuery(status = InvoiceStatus.APPROVED)).collect { invoice -> ... }

`IStreamRequest`

Capability for dispatching a StreamRequest to its handler. Implemented by Mediator.

interface IStreamRequest {
    fun <TRequest : StreamRequest<T>, T> stream(request: TRequest): Flow<T>
}

stream() is non-suspend. It resolves the handler and returns a cold Flow immediately. Each collection starts a fresh RequestContext.

`Notification` · `com.fajrbahr.mediatork.notification`

Marker interface for broadcast events with no response.

interface Notification

`NotificationHandler<T>` · `com.fajrbahr.mediatork.notification`

Reacts to a Notification. Multiple handlers per notification type are allowed.

interface NotificationHandler<in T : Notification> {
    suspend fun handle(notification: T)
}

`PipelineBehavior` · `com.fajrbahr.mediatork.pipeline`

Cross-cutting decorator that wraps each request pipeline.

Member	Type	Default	Description
`stage`	`Stage`	`Stage.Default`	Absolute position group: `Pre`, `Default`, or `Post`
`order`	`Int`	`0`	Position within the stage; lower = outermost
`isEnabled`	`Boolean`	`true`	Skip entirely when `false`
`appliesTo(request)`	`Boolean`	`true`	Opt out for specific request types
`process(ctx, next, req)`	`suspend TResult`	—	Core implementation; must call `next(request)` to continue the chain

`Stage`

Controls the absolute position of a PipelineBehavior in the chain.

Value	Position
`Stage.Pre`	Outermost wrappers
`Stage.Default`	Middle (default)
`Stage.Post`	Innermost wrappers

Stage always beats order. See Pre / Post Behaviors.

Registry & factory

`HandlerRegistry`

Stores all registered handlers. Populated by MediatorRegistrar implementations.

Method	Description
`register(handler)`	Register a request handler (infix, reified)
`registerStream(handler)`	Register a stream request handler (infix, reified)
`registerNotification(handler)`	Register a notification handler (infix, reified)
`registerValidator(validator)`	Register a request validator (reified)
`registerDynamic(klass, handler)`	Register a request handler without reified type (for DI frameworks)
`scope { }`	Group registrations for readability
`+handler`	Operator shorthand for `register` / `registerNotification` inside `scope`
`hasHandler(requestType)`	Returns `true` if a handler is registered for the given request type
`registeredRequestTypes()`	Returns the set of all request types that have a registered handler

`MediatorFactory`

object MediatorFactory {
    fun create(
        registrars: List<MediatorRegistrar> = emptyList(),
        pipelineBehaviors: List<PipelineBehavior> = emptyList(),
        streamPipelineBehaviors: List<StreamPipelineBehavior> = emptyList(),
        notificationPublisher: NotificationPublishStrategy = ParallelNotificationPublisher(),
        verifyHandlers: Boolean = true,
        missingNotificationHandler: NotificationHandler<Notification> = ThrowMissingNotificationHandler(),
        missingRequestHandler: RequestHandler<Request<Any?>, Any?> = ThrowMissingRequestHandler(),
    ): Mediator
}

Parameter	Default	Description
`registrars`	`emptyList()`	Modules that contribute handlers to the registry
`pipelineBehaviors`	`emptyList()`	Cross-cutting decorators; grouped by `Stage` then sorted by `order` within each group
`streamPipelineBehaviors`	`emptyList()`	Cross-cutting decorators for `StreamRequest` dispatches; sorted by `order`
`notificationPublisher`	`ParallelNotificationPublisher()`	Strategy for delivering notifications
`verifyHandlers`	`true`	When `true`, logs a warning for every request type with no handler after all registrars have run
`missingNotificationHandler`	`ThrowMissingNotificationHandler()`	What to do when a notification is published with no registered handlers
`missingRequestHandler`	`ThrowMissingRequestHandler()`	What to do when `send()` is called for an unregistered request type

`MediatorRegistrar`

Contributes handlers to the registry at startup.

interface MediatorRegistrar {
    fun register(registry: HandlerRegistry)
}

Mediator interface

interface Mediator : Sender, IStreamRequest, Publisher

Method	Description
`send(request)`	Dispatch a `Request`; returns `TResponse`. Throws `MissingHandlerException` if no handler.
`stream(request)`	Dispatch a `StreamRequest`; returns a cold `Flow<T>`. Throws `MissingStreamHandlerException` if no handler.
`publish(notification)`	Broadcast a notification using the default `NotificationPublisher`.
`publish(notification, publisher)`	Broadcast a notification using the supplied publisher, overriding the default for this call only.

Notification publishers · `com.fajrbahr.mediatork.notification`

Class	Behaviour
`ParallelNotificationPublisher`	All handlers run concurrently (default)
`SequentialNotificationPublisher`	Handlers run one-by-one; stops on first error
`ContinueOnExceptionNotificationPublisher`	All handlers run; errors collected into `AggregateException`
`FireAndForgetNotificationPublisher`	Returns immediately; handlers run in the background

Exceptions

Class	Description
`MediatorException`	Base class for all MediatorK errors
`MissingHandlerException`	No handler registered for the dispatched request type
`MissingStreamHandlerException`	No stream handler registered for the dispatched `StreamRequest` type
`MissingNotificationHandlerException`	No handlers registered for a published notification type
`AggregateException`	One or more notification handlers failed (from `ContinueOnException…`)

Validator package (`com.fajrbahr.mediatork.validator`)

Type	Description
`RequestValidator<T>`	Validates a request and returns `ValidationResult`. Register via `registry.registerValidator(validator)`.
`ValidationResult`	Sealed class: `Valid` or `Invalid(errors: List<*>)`
`ValidationBehavior`	Pre-built `PipelineBehavior` (order `-50`) that runs registered validators before the handler
`ValidationException`	Thrown when validation fails; `errors: List<*>` carries all failure messages (any type — `String`, sealed class, enum, etc.)
`rules { }`	Collect-all DSL — all `check`/`require` calls run, errors accumulated
`rulesFailFast { }`	Stop-on-first DSL — execution stops at the first failing `check`/`require`
`throwIfInvalid()`	Extension on `ValidationResult` — throws `ValidationException` if the result is `Invalid`

Core interfaces​

Request<out TResponse>​

RequestHandler<TRequest, TResult> · com.fajrbahr.mediatork.handler​

StreamRequest<T>​

StreamRequestHandler<TRequest, T> · com.fajrbahr.mediatork.handler​

IStreamRequest​

Notification · com.fajrbahr.mediatork.notification​

NotificationHandler<T> · com.fajrbahr.mediatork.notification​

PipelineBehavior · com.fajrbahr.mediatork.pipeline​

Stage​

Registry & factory​

HandlerRegistry​

MediatorFactory​

MediatorRegistrar​

Mediator interface​

Notification publishers · com.fajrbahr.mediatork.notification​

Exceptions​

Validator package (com.fajrbahr.mediatork.validator)​