Event-driven design in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is event-driven design?

Event-driven design is a way to build systems where parts talk by sending and reacting to events, like messages that say "something happened." It helps systems work independently and respond quickly.

beginner

What is an event in event-driven design?

An event is a signal or message that tells the system something important happened, like a user clicked a button or a file was uploaded.

beginner

What roles do event producers and event consumers play?

Event producers create and send events when something happens. Event consumers listen for these events and act on them, like updating data or sending notifications.

intermediate

Why is event-driven design good for scalability?

Because parts work independently and communicate through events, you can add more consumers or producers without breaking the system. It handles more work smoothly.

intermediate

What is an event bus or message broker?

It is a middleman that passes events from producers to consumers. It helps organize and deliver events reliably and in order.

In event-driven design, what triggers an event?

A A change or action happening in the system

B A scheduled timer only

C Manual code execution without any change

D Database backup

Events are triggered by changes or actions, like user clicks or data updates.

Which component listens and reacts to events?

A Event producer

B Event consumer

C Database

D Load balancer

Event consumers listen for events and perform actions when events arrive.

What is a benefit of using an event bus?

A It stores all user passwords

B It compiles code

C It routes events between producers and consumers

D It manages user sessions

An event bus routes events to the right consumers reliably.

Event-driven design helps systems to be:

A Independent and scalable

B Slow and unresponsive

C Tightly coupled

D Hard to maintain

Event-driven design promotes independence and scalability by decoupling components.

Which of these is NOT a typical use of events?

A Order placed in an online store

B File upload completes

C User clicks a button

D System clock ticks silently

System clock ticks are usually not events that trigger business logic.

Explain how event producers and consumers interact in event-driven design.

Think of a post office where senders mail letters and receivers read them.

Describe why event-driven design improves scalability and flexibility in software systems.

Imagine a busy restaurant kitchen where chefs work independently but coordinate through orders.