Design a Notification System

1. Problem Statement

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

graph LR
    A["Design a Notification System"]
    A --> F1["Decoupling Durable Queues Between Producers and Channel Workers"]
    A --> F2["Reliability & Retry Strategies Exponential Backoff, Dead Letter Queues"]
    A --> F3["Distributed Deduplication Idempotency Keys with a Uniqueness Check"]
    A --> F4["User Preferences & Compliance Opt-in/Opt-out, GDPR"]
    A --> F5["Rate Limiting & Throttling Per-user vs Per-campaign"]
    A --> F6["Observability Tracing, Delivery Success Rates, Delivery Latency"]

3. Key Focus Areas

• 1
  Decoupling (Durable Queues Between Producers and Channel Workers)
• 2
  Reliability & Retry Strategies (Exponential Backoff, Dead Letter Queues)
• 3
  Distributed Deduplication (Idempotency Keys with a Uniqueness Check)
• 4
  User Preferences & Compliance (Opt-in/Opt-out, GDPR)
• 5
  Rate Limiting & Throttling (Per-user vs Per-campaign)
• 6
  Observability (Tracing, Delivery Success Rates, Delivery Latency)

4. What the Interviewer Looks For

The interviewer probes these areas, and the report grades the interview against them.

• Requirements, priority classes, and capacity
• Pipeline architecture and priority isolation
• Idempotency, retries, and delivery guarantees
• Vendor integration and resilience
• Preferences, compliance, and abuse controls