System requirements

Functional:

• convert long url to short url
• redirect from short url to original url(long url)
• provide custom short url
• track usage (metrics for each shortened url, number of times it has been accessed, geographical data about users)
• user authentication -> should support user accounts, allowing for logging in, manage their urls, view statistics
• url validation -> validate long url format before shortening ensuring it is a well-formed url
• users should be able to set expiration dates for their shortened urls or permanently delete from the system
• system should provide a restful api for developers to automate the url shortening and redirection processes

Non-Functional:

• should be always available
• scalability
• performance should be fast
• should provide protection
• should consistent
• should be maintainable

Capacity estimation

should the number of requests per second = 10.000 r/s

for saving the urls, let's say we're using rdbms database, if every url is to be saved for a long time (no expiration date), let's say 100 years,

1 url size ~ 300kb

100 x 365 x 86400 x 300 = 946080000000 kb ~ 946 tb

should we use redis for faster performance -> using 2:8 rule -> we're using redis 20% of our capacity

20% from 946 tb = 189 tb

API design

shortening :

• create(user_key, long_url, custom_url)

user_key -> for authentication (if guests then default from UI)

long_url -> long_url that is to be shortened

custom_url -> if user want to shorten url with customization

redirection :

• redirect(short_url)

should return 301 redirect

Database design

• should use rdbms for acid transaction

mysql or postgreql would be preferable

table user (

primary key id int,

username varchar,

email varchar,

password varchar,

)

table url(

primary key id int,

long_url varchar,

short_url varchar,

user_id foreignkey user

)

High-level design

You should identify enough components that are needed to solve the actual problem from end to end. Also remember to draw a block diagram using the diagramming tool to augment your design. If you are unfamiliar with the tool, you can simply describe your design to the chat bot and ask it to generate a starter diagram for you to modify...

Request flows

Explain how the request flows from end to end in your high level design. Also you could draw a sequence diagram using the diagramming tool to enhance your explanation...

Detailed component design

Dig deeper into 2-3 components and explain in detail how they work. For example, how well does each component scale? Any relevant algorithm or data structure you like to use for a component? Also you could draw a diagram using the diagramming tool to enhance your design...

Trade offs/Tech choices

Explain any trade offs you have made and why you made certain tech choices...

Failure scenarios/bottlenecks

Try to discuss as many failure scenarios/bottlenecks as possible.

Future improvements

What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?