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:

• Latency - Redirection should be under p95 <= 100ms and p99 <= 200 ms.
• Reliability (redirect from a short url should always go to same long url, it was mapped to)
• Eventual consistency
• Availability - 99.99%
• Scalability - Writes: 100K new URLs/day and Reads: 2M redirects/day

API Design

Endpoints:

• POST /api/shorten - status 201

Request

payload -

{

"url": "string: ",

"userid": "int: "

}

Response:

payload:

{

"alias": "string: ",

}

Status: 200

• GET /r/{alias}

Response:

Status: 301/302/307/308

Location: ""

Data Model

• UrlEntries
  • URL - string - 200 bytes
  • Alias (PK) - string- 7 bytes
  • Timestamp - int - 8 bytes
  • UserId - int - 8 bytes

Back of the envelop Estimation

• Write 100K/day ~= 1.2 write QPS
• Read 2M/day ~= 23 read QPS
• Data storage timeline - 5 Years

1 URL - 223 B ~= 256 B

Writes per day - 100K * 256 B ~= 25.6 MB

Writes per timeline - 25.6 MB * 5 * 365 ~= 40 GB

Indexing + Repication + Sharding ~= 2-3x ~= 120 GB

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.