System requirements

Functional:

1. User should be able to create short URLs for long URLs.
2. Users should be redirected to original long URL when clicked on Short URL
3. Users should be able to register in the system via SSO.
4. Users should be able to track link clicks and be able to view reports.
5. The custom short urls could be created and should not be repeated.

Non-Functional:

1. Minimum latency while redirecting users from short url to long url.

Capacity estimation

This is going to be high reads system. More short links will be clicked then created. There could be 100 users using the system in a day. Each user creating 50 short links in a day. Making it 5000 links created in a day. Each link could be clicked by 10k users in a day. so in total 5 billion clicks in a day.

Lets say each short link needs 10 bytes and long url needs 2000 bytes. So for 5000 links we need

short link storage = 10 * 5000 = 50kB per day.

Long URL storage = 2000 * 5000 = 10Mb per day.

Since this is high read system usage of big data such as mongodb, redshift, etc is preferred.

For storing user's info RDBMS such as mysql could be used.

1. Normal usage:
   • For functionality (1) Creating short URLs: Estimate about 200 requests per second.
   • For functionality (2) Redirecting short URLs to long URLs: Estimate around 20,000 requests per second.
2. Peak usage:
   • During peak times, it's wise to factor in a significant spike. A good guideline might be to prepare for around 2-3 times the normal load for both functionalities. Therefore:
     • Peak for creating short URLs could reach approximately 600 requests per second.
     • Peak for redirecting could go up to about 60,000 requests per second.

API design

1. RegisterUser() => Allows users to register in the system.
2. CreateShortURL(userid, long url)=> This gives short link in response.
3. GetShortURL(userid, long link) => Get short url for a long URL
4. AddShortURLTracking() => Add tracking info when any short url is clicked.
5. GetShortURLReport(link id) => Get reporting data for short URLs.

Database design

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?