Chain of Responsibility design Pattern

The Chain of Responsibility Pattern is a behavioral design pattern that allows an object to pass a request along a chain of potential handlers. When a request is made, it is sent through the chain until a handler is found that can process the request.

Key points of the Chain of Responsibility Pattern:

1. Intent:

   • The main intent of the Chain of Responsibility Pattern is to avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. It allows a chain of objects to handle the request dynamically.

2. Key Components:

   • Handler:
     • Defines an interface for handling requests. It contains a method for handling requests and, optionally, a reference to the next handler in the chain.
   • ConcreteHandler:
     • Implements the Handler interface. It is responsible for handling the requests it is capable of handling and forwarding the rest to the next handler in the chain.
   • Client:
     • Initiates requests and sends them to the first handler in the chain.

3. Dynamic Chain:

   • The chain is typically created dynamically at runtime. Handlers are added to the chain, and the client initiates a request without knowing which handler will eventually process it.

4. Request Handling:

   • When a request is made, it is sent through the chain of handlers. Each handler decides whether it can handle the request. If it can, it processes the request; otherwise, it forwards the request to the next handler in the chain.

5. Loose Coupling:

   • The pattern promotes loose coupling between the sender and receiver of a request. The sender is not aware of which object will handle the request, and each handler doesn't need to know about the entire chain.

6. Advantages:

   • Flexibility: You can add or remove handlers dynamically, allowing for flexible and dynamic request processing.
   • Decoupling: It promotes a decoupled architecture, where the sender and receiver are not tightly bound.

7. Use Cases:

   • The Chain of Responsibility pattern is applicable when multiple objects can handle a request, and the system needs to determine the appropriate handler dynamically.
   • It is useful when the processing order of handlers is not predetermined and can be configured at runtime.

8. Example:

   • Consider a logging system where different loggers handle messages of different severity levels. The Chain of Responsibility pattern could be used to create a chain of loggers, with each logger responsible for handling messages of a specific severity.

In summary, the Chain of Responsibility Pattern provides a way to pass a request along a chain of handlers, allowing for flexible and dynamic handling of requests with reduced coupling between the sender and receiver.