Requirements


Functional Requirements:


  • Create a short URL for a given long URL.
  • Return the long URL associated with a given short URL.
  • The url will be stored for 3 days
  • If the url already exists, it can return the same value
  • Same url can only have limit of 50 requests per minute




Non-Functional Requirements:


  • low latency - every endpoint must have low latency, get must be under 300 ms and post must be under 500 ms. Both must have 95% of acceptable time requests
  • high availability - the system cannot be down even if we have deployments
  • Every service must have at least 2 tasks for redundancy
  • Horizontal scalabilitty:
    • Every task must have auto-scalling configured, if it has over 80% of memory or cpu consumption it must start one new task, if it has under 40% of memory or cpu consumption it must stop one task
    • The database must aways be available, as dynamodb, it can be used sharding
    • Every servicemust have a load balancer to controle the traffic between the tasks defined in ecs cluster


API Design

Define the APIs expected from the system. This is your chance to analyze and define the read and write paths so that you can come up with the high-level design...


POST /shorten

  • URL create to receive a url and return the shorten url

GET /{id}

  • Receive the id and redirect to page


High-Level Design

Clients: Users or apps that will use the url shortening service

API Gateway:

  • Entry of the point for requests. It will have a rate limit implemented to avoid attacks.

Shortener service:

  • The service resposible for shortening the url and return the new url for client. When the client requests POST /shorten, the api-gateway will redirect to this service.
  • To create the shortened url, we can use the snowflake_id (hash these values: machine_id, timestamp, sequence).
    • The machine_id will be the hash of taskArn
    • The timestamp will be at current time
    • sequence is based on same timestamp and always will reset on next timestamp


url-search-service: Service responsible for search the url by the code and redirect to the page. It will use caffeine cache for local cache to reduce load in database

database: dynamodb, will store the id of url and will be de primary key and the original url. It will use horizontally scalabilty, will priorize availability than consistency.






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.