SOLID & Design Patterns Interview Question #39

What is the Mediator Pattern?

Structural, Creational & Behavioral Patterns Junior Beginner

Quick Interview Answer

The Mediator Pattern centralizes communication between collaborating objects so they do not need direct references to one another. Participants communicate through a mediator, which coordinates the interaction.

Detailed Explanation

In application architecture, mediator-style request dispatch can reduce controller-to-service coupling. However, excessive mediator usage can hide control flow and turn the mediator layer into an unnecessary indirection.

Code Example

public interface IMediator
{
    Task<TResponse> SendAsync<TResponse>(
        IRequest<TResponse> request);
}

public record GetOrderQuery(int Id)
    : IRequest<OrderDto>;