System requirements

Functional:

1. It should produce a short URL for a given long URL
2. It should sanitize the URL and make sure it's not malicious
3. When users access the short, it should redirect them to the original website
4. We should expire old links

Non-Functional:

1. The system should be available
2. It should be seamless

Capacity estimation

1 million writes per month * 10kb per write=10 gb per month

120gb per year

API design

1. Check if Short URL Exists

• Description: Check if a short URL already exists for the given long URL.
• Endpoint:

• Query Parameters:

• Response:

1. Verify URL Safety

• Description: Verify if the provided URL is safe and does not contain malicious content.
• Endpoint:

• Request Body:

• Response:

1. Create Short URL

• Description: Create a short URL if it doesn't already exist and the URL is safe.
• Endpoint:

• Request Body:

• Response:

1. Get Long URL

• Description: Retrieve the original long URL associated with a short URL.
• Endpoint:

• Response:

Sample Usage

1. To check if a short URL exists:

1. To verify URL safety:

1. To create a short URL:

1. To get the original long URL:

Database design

| Column Name | Data Type | Description | |---------------|-----------|---------------------------------| | user_id | STRING | Primary key for the user | | long_url | STRING | Original long URL | | short_url | STRING | Shortened URL | | created_at | STRING | Timestamp of short URL creation | | read_count | STRING | Number of times URL was read | | region | STRING | Region associated with the URL |

We will use sharding based on the original URL and a single leader replication to provide fast read throughput

High-level design

 client goes to rate limiter first, the rate limiter will have a maximim requests it can handle, it will put the excess in a message que to be processed later, if message que is full we will deny until que is empty. If rate limiter allows the connection it will go to our api. if the request is a get short we will get the short first seeing if it is in a cache (will use write around cache, with LRU eviction policy) if its not in cache it will read from our db which has sharding and single leader replication. if its a write we will first verify if the short exsists and create another write but with a different user name and time stamp, if it does not we will use verify api safety and if its safe we add it else add it to block list

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?