Chain of Responsibility

• A way of passing a request between a chain of objects
• Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request
• Chain the receiving objects and pass the request along the chain until an object handles it

Handler

• Defines an interface for handling the requests
• Optionally implements the successor link

ConcreteHandler

• Handles requests it is responsible for
• Can access its successor
• If the ConcreteHandler can handle the request, it does so; otherwise it forwards the request to its successor

Client

• Initiates the request to a ConcreteHandler object on the chain