System requirements

Functional:

• User can input an url and receive a shortened url instantly
• The shortened url are saved for a period of time
• There should be a mapping between the original url and shortened url
• user login is not necessary

Non-Functional:

• low latency
• high availability

Capacity estimation

Daily active user = 80,000

Each user makes 5 shortened url per day

80000 * 5 = 400,000 requests / day

400,000 / 86400 ~= 5 qps

5 * 5 = 25 pqs for peak

Each url shorten request will use about 500 bytes of storage: 100 bytes for original url, 15 bytes for shortened url, some metadata

500 bytes * 400000 * 365 * 3 ~= 205 GB storage used

API design

/shorten

Request { url, user_id }

Response { shortened_url }

/get_history

Request { user_id, start_time, end_time }

Response { [original_url : shortened_url] }

Database design

UrlTable

user_id, domain, original_url, shortened_url, last_used, expiration_time

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

ShortenService - method used to shorten the url

Database - tradeoffs in choosing SQL vs. NoSQL

Eventual consistency

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?