System requirements

Functional:

• generate a short-url based on the long URL provided, this mapping should be unique
• Given a short URL, redirect to long URL
• (Optional) If we want the user to modify/delete/customize their short URL, we will also implement a user login/register system
• A dashboard that allows users to track usage of their short URLs.
• An API management system allowing developers to generate API key to access the API for automatically short url generation

Non-Functional:

List non-functional requirements for the system...

• Consistent - the same short URL should also lead to the same original URL
• Aavaibility - should be available at least 99.99%
• Scalability - should be able to handle 10k requests per second and about 10M requests per minute.
• The app is gonna be way more read heavy than write, estimation from 500:1 to 1000:1

Capacity estimation

Estimate the scale of the system you are going to design...

API design

Define what APIs are expected from the system...

POST /auth/login authenticates the user when trying to register/login

input: username/email, password

return: authenticated token

error:

404 user not found

403 incorrect password

500 internal server error

POST /url/generate Generate an unique & random URL that's based on the input long URL (optional param: custom short URL) (authenticated using web token or API key)

header: token

input: long URL, custom short URL (optional), expiration (optional)

return: shortURL created

error:

400 URL already taken (if custom provided)

401 token not valid

404 the long URL cannot be accessed (404)

405 the input long URL is of wrong format

500 internal server error

GET /url/list Get the list of URLs the user has generated

header: token

return: list of shortURLs created by the user

error:

401 token not valid

404 no URLs have been ever created by the user

500 internal server error

GET /url/metrics get analytics based on the given shortURL (simialr to above)

header: token

input: short URL

error:

401 token not valid

403 the URL is not owned by the user

404 short URL does not exist

500 internal server error

GET /{short_url} redirect to long URL once accessed at short URL

input: short_url

error:

404 short URL not found

Database design

Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your design...

user table

user_id : primary key, serial

username : varchar

password: SHA-256 hashed

email: varchar

session table:

token : primary key

user_id: foreign key

URLs:

short_URL : primary key, varchar

long_URL : string

expiration : time

analytics:

short_URL : primary key, foreign key

views : xxx

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?