System requirements

Functional:

• Ability to generate a shortened URL from a given URL
• Ability to visit the original URL given the shortened URL

Non-Functional:

• Availability over Consistency -> It is more important that a shortened URL can be accessed than that its properly updated at all times
• Read capacity over write capacity -> Users will likely be using many more shortened URLs than creating them

Capacity estimation

Estimate the scale of the system you are going to design...

API design

POST /url

body: {

url: string

}

{

shortened_url: string

}

GET /url/:tinyurl

{

url: string

}

Database design

Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your design...

Utilize a key-value store with some non-relational database like DynamoDB where the Key is the shortened URL and the value is the original URL. This allows for O(1) lookup and retrieval.

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...

Because this is such a high-read ecosystem, we should utilize primary/secondary databases to handle the higher read values. This also allows for redundancy. In the case of the primary database failure, we can promote a secondary database. We should also utilize a cache (either Redis or memcache) with LFU to store the 30 most frequently used urls for faster retrieval. We are going to use an active-passive load balancer scheme, where a load balancer listens to see if the main load balancer goes down, and in that case takes over.

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?