Requirements

Functional Requirements:

• Record ad clicks from users across websites in real time, including client metadata (cookies, IP addresses, browser string), ad_ID, and timestamp.
• Aggregate click data by time window (second, minute, hour) to provide click counts per ad.
• Provide audience info (age, gender, geo location) and showing where users engage, like specific websites or platforms, breakdowns in reports for advertisers.

Non-Functional Requirements:

• Availability for view reports, 99.99%, 52 minutes downtime in a year.
• Consistency eventually for click counts
• Hot key: hot websites
• idempotency for ads clicks, e.g. # of clicks in a second from the same user counted as 1
• Low latency: Ensure aggregation completes within a few minutes.
• Scalability: able to serve 1B clicks per day, and grows 30% per year
• Fault tolerance: Recover from failures using snapshots and replaying events.
• Realtime dashboard: able to see clicks in real time

API Design

collect clicks from FE

POST /v1/track/clicks: request:{clickEvent}

view clicks reports

Report query

GET /v1/reports/ads/{adId}/clicks?start={}&end={}

GET /v1/reports/ads/{adId}/clicks?campaignId={}&breakdown=age,geo,gender&channel=website

These endpoints are used

above GET all need JWT as advertiser/admin login as authentication, and rule-based authorization. advertiser can access their own ads/campaigns/..

admin has broader access scope

High-Level Design

Describe the overall system architecture. Identify the main components needed to solve the problem end-to-end. Use the diagramming tool to create a block diagram.

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.