Chain of Responsibility pattern in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of the Chain of Responsibility pattern?

It allows multiple objects to handle a request without knowing which one will handle it. The request passes along a chain until an object handles it.

intermediate

How does the Chain of Responsibility pattern help in system design?

It decouples the sender of a request from its receivers by giving multiple objects a chance to handle the request, improving flexibility and scalability.

beginner

In the Chain of Responsibility pattern, what role does each handler play?

Each handler decides either to process the request or to pass it to the next handler in the chain.

beginner

What is a real-life example of the Chain of Responsibility pattern?

Customer support: A request goes from a junior agent to a senior agent, then to a manager until someone can solve the problem.

intermediate

What is a key benefit of using the Chain of Responsibility pattern in software systems?

It allows adding or changing handlers dynamically without changing the sender or other handlers, making the system easier to maintain and extend.

What happens if no handler in the Chain of Responsibility can process the request?

A The request is ignored or dropped.

B The request is processed by the first handler anyway.

C The system throws an error immediately.

D The request is sent back to the sender.

If no handler can process the request, it usually gets ignored or dropped as it passes through the chain.

Which of the following best describes the Chain of Responsibility pattern?

A A chain of objects where each can handle or pass a request.

B A single object handles all requests directly.

C Objects communicate by broadcasting messages to all handlers.

D Handlers process requests in parallel.

The pattern involves a chain of objects where each decides to handle or pass the request.

How does the Chain of Responsibility pattern improve system flexibility?

A By requiring all handlers to process every request.

B By hardcoding all handlers in the sender.

C By processing all requests in a fixed order without skipping.

D By allowing handlers to be added or removed without changing the sender.

Handlers can be added or removed dynamically, so the sender does not need to change.

In the Chain of Responsibility, what is the typical structure of handlers?

A Handlers are stored in a global list accessed by all.

B Handlers communicate through a central dispatcher.

C Each handler has a reference to the next handler in the chain.

D Handlers are independent and do not know about each other.

Each handler holds a reference to the next handler to pass the request along.

Which scenario is NOT a good fit for the Chain of Responsibility pattern?

A When multiple objects can handle a request in sequence.

B When all handlers must process the request simultaneously.

C When you want to add or remove handlers easily.

D When the sender should not know which object handles the request.

The pattern is for sequential handling, not simultaneous processing.

Explain the Chain of Responsibility pattern and how it helps in designing flexible systems.

Think about how a support ticket moves through different levels of help.

Describe a real-world example of the Chain of Responsibility pattern and how it works step-by-step.

Imagine passing a question from a junior to a senior person until someone can answer.