System requirements

List functional requirements for the system (Ask the chat bot for hints if stuck.)...

URL Encoding: When a user enters a URL, the system generates a unique short alias. This could be done by creating a hash of the URL and then encoding it. The encoded string will serve as the key in the key-value pair, where the value is the original URL.
Redirection: When a user accesses the shortened URL, the system looks up the original URL associated with the encoded string and redirects the user to that URL.
Data Storage: The system needs to store the mapping between the shortened URL and the original URL. This could be done using a database or a distributed key-value store.
Expiration and Cleanup: Optionally, the system could allow URLs to expire after a certain period of time. This would require a cleanup process to remove expired URLs from the system.

List non-functional requirements for the system...

Scalability: The system should be able to handle a large number of URL shortenings and redirections. This could be achieved by using load balancers and distributed databases.
Availability and Consistency: The system should be highly available and consistent. This means that if a user shortens a URL, they should be able to access the shortened URL immediately. Also, the same shortened URL should always redirect to the same original URL.