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

・Low Latency

・Scalability

API Design

1. Create Short URL

- Endpoint: POST /api/v1/shorten

- Request Body: { "long_url": "https://example.com/very-long-page" }

- Response: { "short_url": "https://tiny.url/abc123" }

2. Redirect

- Endpoint: GET /{short_url_id}

- Response: 302 Redirect to long_url

High-Level Design

The system follows a standard microservices architecture to ensure high availability and scalability.

1. Load Balancer: Distributes incoming requests to multiple web servers to prevent bottlenecks.

2. Web Servers: Handles incoming API requests for URL shortening and redirection.

3. Cache (Redis): Stores frequently accessed mappings to ensure low-latency redirection.

4. Database: Provides persistent storage for all URL mappings.

Detailed Component Design

1. Short ID Generation

To generate a unique short ID, we use an auto-incrementing counter converted to Base62. A 7-character ID provides enough combinations for our scale.

2. Database Selection

We choose a NoSQL database like DynamoDB because it handles high write throughput and horizontal scaling better than traditional RDBMS.

3. Caching Strategy

Since the read-to-write ratio is high, we use an LRU eviction policy in Redis. This keeps popular URLs in memory, reducing the load on the database.