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:

• What is the traffic volume - 100 Million urls generated per day
  1. let say write to read ration is 1:10
  2. reads per day assumed - 1000 million
• length of short URL - as short as possible
• what characters are allowed in the short URL - a-zA-Z0-9 (62 characters)
• can short URLs be deleted or Updated - let's say No
• Highly available, low latency, reliable, expandable

API Design

APIs

1. Write - POST - api/v1/data/shorten
   1. request parameters - longURL: longURLString
   2. response - short URL
2. Read - GET - api/v1/shortURL
   1. returns long URL associated and redirect with 301 response status code

High-Level Design

clinet - URLshortner server - url server, hash function , database

Detailed Component Design

1. Database - Key-value pair (short URL - Long URL). why not hash table (because its a in-memory store and in long term it will be limited and won't be expandable and feasible for production ready systems, data persistence in not gurenteed in an in memory db as it loses when the system crashes or restarted etc..) - Use relational Database - reliable, persitent data, scalable, consistent, multi-user coprative
2. Hash function - used to hash the lng url into short url
   1. hash value will consist a-zA-Z0-9 charaters (total 62 characters)
   2. to generate 100 million * 365 days * 10 years = 365 billion URLs - 62^n >= 365 billion = n=7 that means 7 character length would be enough to create these many URls
   3. generate a hashfunction that will take the long URL and create short URL code
3. URL redirecting