Requirements

Functional Requirements:

• Create a short URL for a given long URL.
• Return the long URL associated with a given short URL.

Non-Functional Requirements:

• Scalability
  • Messaging queues for creating shortened URLs
  • NoSQL so horizontal scaling can be supported
  • Base62 Counter for shortened URL IDs
• Low latency
  • CDN network for frequently accessed short URLs
  • Redis caching layer with LRU
• High availability

API Design

Define the APIs expected from the system. This is your chance to analyze and define the read and write paths so that you can come up with the high-level design...

Write

• POST /shorten
  • Long URL is sent and stored
  • Returns a short URL

Read

• GET /shortenedId
  • Short URL is sent
  • Returns 302 and a redirect to the long URL page

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.

Load balancer + API Gateway

• Directs requests to either shorten the URL or get the shortened URL

URL Shortening Service

• Creates the shortened URL using an incremental UUID + Base62 for ID generation

Redirect Service

• Looks up the shortenedId get the long URL for the client
• CDN, Redis, then NoSQL

NoSQL Database

• Stores long URL to short URL mappings
• Easy to scale horizontally

Caching Layer

• CDN Network
• Redis Cache

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.