Design a high-throughput Notification System
Last updated: April 18, 2026
Quick Overview
Design a high-throughput notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia
April 18, 202635
12
3,135 solved
Design a high-throughput notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia asks this during the Onsite to assess your depth in software engineering. They want to see understanding of design patterns, system architecture, and the trade-offs involved in different technical approaches.
What the Interviewer Expects
- Apply engineering principles to a realistic design scenario
- Discuss trade-offs between different approaches with concrete examples
- Demonstrate understanding of testability, maintainability, and extensibility
- Connect theoretical concepts to production engineering practices
- Discuss how the approach scales with team and codebase size
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 this design change if the team size doubled?
- What testing strategy would you use for this component?
- How would you measure the performance of this component in production?
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Core Design Principles
For designing a high-throughput notification system at Expedia, we should adhere to the following core design principles:
- Separation of Concerns: This principle ensures that different aspects ...
Architecture
The architecture of the notification system will use a microservices approach, leveraging the following components:
- API Gateway: This will handle incoming requests and route them to the approp...
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