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:

• Low-latency:
  • Application deployed in continents
  • A geo load-balancer
  • A load-balancer in continental regions, to handle internal replicas
• Scalability, Availability:
  • The load balancers's take care of this
• Reliability:
  • Geo load-balancer's handle application run-time reliability
  • For database:
    • Master (with replicas) to route to the location of database
    • Continental database, with replication in nearst continent database

API Design

• User management apis
  • registration
  • authentication
  • user edit related apis
  • user delete
• Url shortening apis
  • public url shortening
  • for registered users, to use custom defined domain name
• Custom domain management apis
  • CRUD to manage user custom domains
• Shortened url management for user
  • CRUD to manage
• Url redirector apis

High-Level Design

• Application runtime
  • Geo load balancer
  • Regional load balancer
  • Application runtime
• Application database
  • Master - stores geological data
  • Continental Database - continental info with replica of nearst
  • Low level master - handles replication to ensure availability
  • Actual database

Workflow:

• Request goes to geo load balancer
• It determines which regional load balancer to invoke
• region load balancer decides an application runtime instance to serve the request
• the db request goes to geo master
• geo master finds the location of the actual data, and redirects to the continental database
• eventually reaches the actual database
• cache at continental level

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.