System requirements

Functional:

• should be able to create shortened URLs
• reduce longer URL
• smallest length posisble
• collect click metrics to be later used for the longer URL as well
• stay permanent

Non-Functional:

• should always be up and running
• should be fast
• replicate the functionality of the longer URL (i.e. calling other service APIs)

Capacity estimation

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

API design

• /create:
  • will create the shorter URL by taking longer URL in the request body and return 200OK if successful or return error if not.
• /get:
  • gets the shorter URL for the longer URL from the DB and return 200OK or not.
• /delete:
  • delete the short URL if no longer needed.

Database design

• we would need relational DB like Mysql or postgres.

DB1:

• stores info about the URL itself. it will have the following columns: shortURL, corresponding longURL and the id is the primary ID of the user or service that requested the shortening, and datetime of when the URL was created.

DB2:

• stores info about the user/service that is requesting the shortening. the columns are ID (primary ID of the user/service). name, email, etc.

High-level design

on a high level we will have client and database.

the client has two functions:

• to request a short URL:
  • the client gets back the short URL for the long url
  • hits a webserver
  • in the backend there will be logic/code called to shorten the URL and store in the DB
• to access the URL.
  • the client is redirected to the long URL when accessing the shortURL.
  • hits a webserver
  • in the backend there will be logic/code called to get the long URL from the short URL from the DB and hit that URL instead.

In order to avoid latency if multiple requests are coming, then we need to add load balancers in front of the webserver and perhaps increase the webservers and also partition the DBs so that balanced requests are managed accordingly. (for example if they are coming from different locations then they go to the server closest to their region and hits the right DB partition).

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?