Requirements

Functional Requirements:

• Create a short URL for a given long URL.
• Return the long URL associated with a given short URL.

Non-Functional Requirements:

• High Availability: This requirement ensures that the service remains operational and accessible even during failures. For your design, consider implementing redundancy and failover mechanisms to minimize downtime.
• Low Redirect Latency: Users expect quick responses when they click on shortened URLs. Aim for a redirect latency of milliseconds. This can influence your choice of caching strategies and data storage solutions.
• Horizontal Scalability: As your service grows, it should handle increased traffic by adding more servers rather than upgrading existing ones. Design your architecture to support load balancing and partitioning of data to achieve this.
• Traffic Estimation: Understanding the read vs. write ratio and growth projections is crucial. This informs your database design and helps in resource allocation to handle peak loads.
• Storage Estimation: Calculate the expected size of the URL mapping table based on anticipated usage. This will guide your choice of storage technology and indexing strategies.
• Reliability & Fault Tolerance: Identify single points of failure and plan for disaster recovery. This is essential to maintain service continuity.

API Design

API needs to handle two primary functionalities: receiving long URLs to generate short URLs and converting short URLs back to their original long URLs.

• Short URL Creation: When a user submits a long URL to your API, it should generate a unique identifier (short code) and store the mapping of this short code to the long URL in a database. The API then returns the short URL, which typically combines a base URL with the short code.
• URL Resolution: When a user accesses a short URL, the API should extract the short code, look up the corresponding long URL in the database, and redirect the user to that long URL.

High-Level Design

Describe the overall system architecture. Identify the main components needed to solve the problem end-to-end. Use the diagramming tool to create a block diagram.

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.