System requirements

Functional:

1. It should have the ability to generate short URLs
2. It should be able to redirect user to the long URL when the short URL is typed.

Non-Functional:

1. Low latency is required in redirection from short to long URL.
2. Should be able to handle multiple URL shortening and redirection requests at the same time.

Capacity estimation

The number of users using our service can suppose scale up to the following numbers:

1. 10 million redirection requests per day.
2. 1 million URL shortening requests per day.

This corresponds to 30 million new URL creations per month. In 5 years, that will be (12*5*30 million=1.8 billion) new URLs in 5 years.

API design

We can also design a REST API for our service to allow users to make URL shortening requests with their system. We should also place a cap of let's say 100 requests per day for an API key.

Database design

We will store both the short and long URLs. Suppose the total length per short+long URL is 100.

The database would need a space of 180 billion characters (i.e., approx. 150 GB-200 GB). So, we can keep our database to be of size 1 TB to be safe.

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?