System requirements

Functional:

1. User should be able to provide actual url which needs to be shortened (POST/PUT API)
2. User should be able to find actual url from shortened urls (GET API)
3. User should be able to redirect to actual url by hitting short url's ( GET)

Non-Functional:

1. Highly available as it can be a single point of failure for all api calls if redirection fails.
2. Security is major concern as unauthorized user should not be able to accces url's
3. Data should be consistent and distributed with caching implementation for faster access as latency should be low.
4. Faster response as it should not be an overhead for api's
5. Data integrity we should redirect to wrong url's which may provide unauthorized access to users.

Capacity estimation

1. 200 users per min hitting api

2.API takes 1 sec to shorten url

3.Atleast 100 request to shorten url every min

API design

POST API to shorten url and save it in database.

Request - url Body -actual url as json Response status code

GET API to fetch details on shortened url.

Request -url/shortened url or can use id stored in db for uniqueness

Response - actual url /shortened url / id / user created

GET API to redirect users to actual url

just hit short url

GET API to fetch all mappings created by user based on device id or user id

url/user-id

Resonse give details as a list actual url /shortened url / id / user created

Database design

Database can be unstructured to avoid complication as we dont need any complex queries its required to persist data

Mongo or dynamo db would work

User table - id |user id|user name| user email

shortened_url - id| user id| actual url | shortned url

access_control - id | user id | access | actual url

High-level design

KAFKA to trigger event in case url got changed after expiration and to generate new url as well

Dynamo db

Redis cache to cache url as they wont change frequently eventual consistency

sharding range based for faster access

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?