Core Concepts

Core Concepts

Mediatron is built around a few simple ideas. Understanding them makes the rest of the wiki easy to follow.

The Mediator Pattern

Instead of your controllers or services calling business logic classes directly, they send a message to a mediator. The mediator finds the correct handler and runs it. This keeps your code decoupled — the sender does not need to know which class handles the work.

CQRS (Command Query Responsibility Segregation)

Mediatron splits your operations into two kinds of "requests":

• Commands — actions that change data (e.g., CreateProductCommand).
• Queries — actions that read data (e.g., GetProductByIdQuery).

Both are modeled with the same IRequest / IRequest<TResponse> interfaces, so you can send them the same way.

Pub/Sub Notifications

Sometimes one action should trigger multiple side effects — for example, sending an email and logging an event when a product is created. Mediatron supports this with INotification and INotificationHandler<T>. One notification can have many handlers, and they all run when the notification is published.

Pipeline Behaviors

A Pipeline Behavior wraps around a request handler, so you can run code before and after it runs — without touching the handler itself. This is useful for cross-cutting concerns like logging, timing, or validation. Behaviors are set up with IPipelineBehavior<TRequest> or IPipelineBehavior<TRequest, TResponse>, and Mediatron registers them automatically, just like handlers.

Main Building Blocks

Concept	Purpose
IRequest / IRequest<TResponse>	Marks a class as a command or query.
IRequestHandler<TRequest, TResponse>	Contains the logic that handles a request.
INotification	Marks a class as an event.
INotificationHandler<TNotification>	Contains the logic that reacts to an event.
IPipelineBehavior<TRequest> / IPipelineBehavior<TRequest, TResponse>	Wraps logic (e.g., logging, validation) around a request handler.
IMediator	The main entry point used to send requests and publish notifications.

See Requests and Handlers (CQRS), Notifications (Pub/Sub), and Pipeline Behaviors for full examples.