System requirements

Functional:

• Shortening service (get long url from user, shorten it)
• Posting service (take short url and give back long url to user)

Non-Functional:

• Global need: Yes
• 100M requests / day
• Expiration: after 6 months, delete data
• URL should be alphanumeric

Capacity estimation

Not sure

API design

A shortening service (shortens the long url) and a posting service (returns back the long url from the saved short url)

Database design

DynamoDB database that stores key values

Key = short url

value = long url

We can keep some metadata like userID (int) and clicks (int) for some future analysis

I chose a NoSQL database due to its TTL functionality where we can ask it to delete key/values daily once it has reached 6 months.

High-level design

User/client provides long url

Server should reference two services: shortening url service and posting service.

When the URL is shortened it is stored in a noSQL database.

When the short URL is used by the client again, it will check against the DB to return back the long url & complete the job.

Request flows

Its in the diagram

Detailed component design

Given the high volume of requests, we need to scale to have a pool of servers or pool of databases.

For frequently visited short URLs, we might implement caches if our website gets popular enough.

Trade offs/Tech choices

Failure scenarios/bottlenecks

People may get the same short URL back as we didnt build for checks of that nature here.

Future improvements

Include an additional database (relational) so we can ensure different users do not get the same shortened URL.