Chain of Responsibility Pattern:
The Chain of Responsibility is a behavioral design pattern that lets you pass requests along a chain of handlers. Upon receiving a request, each handler decides whether to process it or pass it on to the next handler in the chain.

In other words, this pattern allows a number of classes to attempt to handle a request independently of any other object along the chain. It creates a loose coupling and promotes the separation of concerns by isolating the handling and routing of the request.

Imagine the parcel delivery process: When you send a parcel to a remote place, the parcel goes through several post offices from origin to destination. Each post office (handler) has the opportunity to either forward the parcel to the next office or deliver it if the final destination is within its coverage area.

In another example, let's handle the authentication and authorization of a backend request. Here is the implementation in Go:


In this example, a request goes through the "AuthenticationHandler" first. If authentication succeeds, it's passed on to the "AuthorizationHandler". If that succeeds, the request continues to be processed. If any handler fails, the processing is stopped and an error is returned.