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:

• Low latency. We want those urls to be resolved fast.
• Redirection if the id changes from a generated id to a custom-id.
• scalability, How we we resolve urls fast
• High availability
• Not sure the eventual consistency.

API Design

From an API design POV it's quite simple. Let's start with the endpoingt:

• POST /create
  • Body: url, possibly a custom id

High-Level Design

We are talking here about 5 layers.

• The client layer
• The global edge layer
• The application layer
• The Async workers layer
• And the Data layer

All of them are connected to each other.

The Client layer makes HTTp requests to the CDN on the global edge layer, which is filtered by a WAF, the traffic then proceeds to the API Gateway which then routes to the write service and save it in a noSQL db for store mapping and redis for cache warming. Once a write happen, an async job also saves analytics on the analytics DB. When a client navigates to a URL, we're routes to the read service wich will first check the redis, and if there is a cache miss we're reading from the MongoDB

Detailed Component Design

• Client: The client side makes the requests to create a new short URL