Design a event-driven Messaging System
Last updated: December 3, 2025
Quick Overview
Design a event-driven messaging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Roblox
December 3, 202510
3
1,743 solved
Design a event-driven messaging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This fundamentals question from Roblox's System Design Round tests whether you can reason about software design at a deep level. The interviewer expects discussion of maintainability, testability, and operational considerations.
What the Interviewer Expects
- Explain the concept clearly with a practical example
- Discuss when and why to apply this principle
- Identify common mistakes and anti-patterns
- Compare with alternative approaches
Key Topics to Cover
How to Approach This
- Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
- Choose data structures based on access patterns, not familiarity.
- Prefer immutable data and message passing over shared mutable state for concurrency.
- Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
- What are the security implications of this design?
- How would you document this for other engineers?
- How would you measure the performance of this component in production?
- How would this design change if the team size doubled?
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Core Design Principles
For the event-driven messaging system at Roblox, the core design principles that apply are:
- Single Responsibility Principle (SRP): Each component in the messaging system should have one reason...
Architecture
The architecture for the event-driven messaging system at Roblox would include:
- Message Broker: A central component (like RabbitMQ or Kafka) that handles message routing and delivery between p...
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