REST API best practices in HLD - Architecture Diagram

System Overview - REST API best practices

This system provides a REST API following best practices to ensure scalability, security, and maintainability. It handles client requests through a load balancer and API gateway, routes them to microservices, uses caching for faster responses, and stores data in a database.

Architecture Diagram

User
  |
  v
Load Balancer
  |
  v
API Gateway
  |
  v
+-------------------+
|   Microservices    |
|  (REST API Logic)  |
+-------------------+
  |
  v
Cache <--> Database

Components

User

client

Sends HTTP requests to the REST API

Load Balancer

load_balancer

Distributes incoming requests evenly across API gateway instances

API Gateway

api_gateway

Handles authentication, rate limiting, and routes requests to microservices

Microservices

service

Implements REST API endpoints following best practices

Cache

cache

Stores frequently accessed data to reduce database load and improve response time

Database

database

Stores persistent application data

Request Flow - 11 Hops

User → Load Balancer

Load Balancer → API Gateway

API Gateway → Microservices

Microservices → Cache

Cache → Microservices

Microservices → Database

Database → Microservices

Microservices → Cache

Microservices → API Gateway

API Gateway → Load Balancer

Load Balancer → User

Failure Scenario

Component Fails:Database

Impact:New data writes fail and fresh data cannot be retrieved; cached reads still work but may be stale

Mitigation:Use database replication and failover to standby database; rely on cache for read availability during failover

Architecture Quiz - 3 Questions

Which component is responsible for distributing incoming user requests evenly?

A Cache

B API Gateway

C Load Balancer

D Database

Design Principle

This architecture demonstrates REST API best practices by using a load balancer for scalability, an API gateway for security and routing, microservices for modularity, caching to improve performance, and a database for persistent storage. Each component has a clear role, and the request flow ensures efficient and secure handling of client requests.

Practice

1. Which HTTP method is typically used to update an existing resource in a REST API?

easy

A. PUT

B. GET

C. POST

D. DELETE

Solution

1. Step 1: Understand HTTP methods for REST

   GET retrieves data, POST creates new resources, PUT updates existing resources, DELETE removes resources.

2. Step 2: Identify method for updating

   PUT is the standard method to update or replace an existing resource in REST APIs.

3. Final Answer:

   PUT -> Option A

4. Quick Check:

   Update = PUT [OK]

Hint: Update resource? Think PUT method [OK]

Common Mistakes:

• Confusing POST with update instead of create
• Using GET for updates
• Using DELETE to update

2. Which of the following is the correct way to version a REST API in the URL?

easy

A. /v1/api/resource

B. /api/resource/v1

C. /api/v1/resource

D. /api/resource?version=1

Solution

1. Step 1: Understand common versioning patterns

   Versioning is often done in the URL path to clearly separate API versions.

2. Step 2: Identify correct version placement

   Placing version immediately after the base API path, like /api/v1/resource, is standard practice.

3. Final Answer:

   /api/v1/resource -> Option C

4. Quick Check:

   Version in path = /api/v1/ [OK]

Hint: Version goes right after /api/ in URL path [OK]

Common Mistakes:

• Putting version after resource name
• Using query parameters for versioning
• Placing version before /api/

3. Given the following API response status codes, which one indicates a successful resource creation?

{
  "status": 201,
  "message": "Created"
}

medium

A. 200 OK

B. 201 Created

C. 400 Bad Request

D. 404 Not Found

Solution

1. Step 1: Review HTTP status codes for success

   200 means success for general requests, 201 means resource created successfully.

2. Step 2: Match status code to creation

   201 Created is the correct code to indicate a new resource was successfully created.

3. Final Answer:

   201 Created -> Option B

4. Quick Check:

   Creation success = 201 [OK]

Hint: 201 means resource created successfully [OK]

Common Mistakes:

• Confusing 200 with creation success
• Using 400 or 404 for success
• Ignoring status code meaning

4. A developer designed a REST API endpoint as POST /users/delete to delete a user. What is the best fix to follow REST API best practices?

medium

A. Change to GET /users/delete

B. Keep POST /users/delete but add a query param

C. Use PUT /users/delete

D. Change to DELETE /users/{id}

Solution

1. Step 1: Identify correct HTTP method for deletion

   DELETE method is the standard for removing resources in REST APIs.

2. Step 2: Correct endpoint structure

   Use resource identifier in URL path like /users/{id} with DELETE method for clarity and REST compliance.

3. Final Answer:

   Change to DELETE /users/{id} -> Option D

4. Quick Check:

   Delete resource = DELETE /resource/{id} [OK]

Hint: Use DELETE method with resource ID in URL [OK]

Common Mistakes:

• Using POST for delete actions
• Using GET to delete resources
• Adding delete action in URL path

5. You want to design a REST API that returns a list of products with optional filtering by category and price range. Which approach follows REST API best practices?

hard

A. GET /products?category=electronics&min_price=100&max_price=500

B. POST /products/filter with JSON body containing filters

C. GET /products/filter/category/electronics/price/100-500

D. PUT /products with filter parameters in the body

Solution

1. Step 1: Understand filtering in REST APIs

   Filtering is best done using query parameters in GET requests to keep APIs simple and cacheable.

2. Step 2: Evaluate options for filtering

   GET /products?category=electronics&min_price=100&max_price=500 uses GET with query parameters, which is standard and clear. Other options misuse POST or PUT or complex URL paths.

3. Final Answer:

   GET /products?category=electronics&min_price=100&max_price=500 -> Option A

4. Quick Check:

   Filter with GET query params [OK]

Hint: Use GET with query parameters for filtering [OK]

Common Mistakes:

• Using POST or PUT for filtering
• Embedding filters in URL path segments
• Sending filters in request body for GET