Event types (domain, integration, notification) in Microservices - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify the primary purpose of domain events

In a microservices architecture, what is the main role of domain events?

A To notify external systems about changes in business state

B To synchronize databases across different microservices

C To communicate changes within the same bounded context or service

D To trigger user interface updates directly

💡 Hint

Think about events that represent changes inside a single service's business logic.

Domain events represent significant changes within a service's own business logic or bounded context. They are used internally to decouple components within the same service.

❓ Architecture

intermediate

Choose the correct event type for cross-service communication

Which event type is best suited for notifying other microservices about a change that happened in one service?

A Domain event

B Integration event

C Notification event

D Command event

💡 Hint

This event type is designed to share information between different services.

Integration events are used to communicate changes between different microservices, enabling them to stay in sync without tight coupling.

❓ scaling

advanced

Scaling notification events for user alerts

You have a notification event system that sends alerts to users. What is the best approach to scale this system when user count grows rapidly?

A Use a message queue to asynchronously process notification events and send alerts

B Send notifications synchronously within the main service processing user actions

C Store notifications in the database and send them only when users log in

D Send notifications directly from the database triggers

💡 Hint

Think about decoupling notification sending from main user action processing.

Using a message queue allows the system to handle notification events asynchronously, improving scalability and responsiveness.

❓ tradeoff

advanced

Tradeoffs between domain and integration events

What is a key tradeoff when choosing between domain events and integration events in microservices?

A Integration events are synchronous, domain events are always asynchronous

B Integration events require tight coupling between services, domain events do not

C Domain events are easier to version but harder to scale across services

D Domain events are internal and simpler but do not notify other services, integration events enable cross-service communication but add complexity

💡 Hint

Consider scope and complexity of each event type.

Domain events are internal to a service and simpler to manage, while integration events enable communication between services but require more coordination and versioning.

❓ estimation

expert

Estimate event throughput for a notification system

A notification system sends notification events to 1 million users daily. Each user receives on average 3 notifications per day. What is the approximate average event throughput per second the system must handle?

A About 35 events per second

B About 120 events per second

C About 120,000 events per second

D About 35,000 events per second

💡 Hint

Calculate total events per day, then divide by seconds in a day (86400).

Total events = 1,000,000 users * 3 notifications = 3,000,000 events/day.
Seconds per day = 86400.
Throughput = 3,000,000 / 86400 ≈ 34.7 ≈ 35 events/second.