REST vs GraphQL

REST Architecture

Multiple endpoints:
  GET /rest/V1/products
  GET /rest/V1/products/123
  GET /rest/V1/categories
  GET /rest/V1/customers
  POST /rest/V1/carts

GraphQL Architecture

Single endpoint:
  POST /graphql
  
  Query determines response:
  query {
      products { items { name, sku } }
      categories { items { name } }
  }

Key Differences

Data Fetching

# REST: Get product with category (2 requests)
GET /rest/V1/products/123
GET /rest/V1/categories/5

# GraphQL: Get product with category (1 request)
query {
    product(sku: "123") {
        name
        category {
            name
        }
    }
}

REST Advantages

• Simple to implement
• HTTP caching built-in
• Wide tooling support
• Easy to understand
• Standard HTTP methods
• Mature ecosystem

REST Disadvantages

• Over-fetching common
• Under-fetching requires multiple requests
• Multiple endpoints to maintain
• Versioning complexity
• Fixed data structure

GraphQL Advantages

• Precise data fetching
• Single request for related data
• No over/under-fetching
• Strongly typed schema
• Introspection for documentation
• Flexible queries

GraphQL Disadvantages

• Complex caching
• Learning curve
• Query complexity issues
• N+1 problem potential
• Less tooling than REST
• No HTTP caching

Comparison Matrix

REST Scenarios

1. Simple CRUD Operations

   GET /products
   POST /products
   PUT /products/123
   DELETE /products/123
   

2. File Uploads

   POST /rest/V1/products/123/media
   Content-Type: multipart/form-data
   

3. Webhooks

   POST https://webhook-url.com
   Content-Type: application/json
   { "event": "order.created", "data": {...} }
   

4. Third-Party Integration

   • Many services support REST
   • Standard authentication
   • Easy to integrate

5. Caching Required

   • HTTP caching built-in
   • CDN support
   • Browser caching

REST Best Practices

# Use proper HTTP methods
GET - Read
POST - Create
PUT - Update
DELETE - Remove

# Use proper status codes
200 - Success
201 - Created
400 - Bad Request
404 - Not Found

# Use pagination
GET /products?page=1&limit=20

GraphQL Scenarios

1. Complex Data Requirements

   query {
       product(sku: "123") {
           name
           price { value }
           category { name }
           reviews { items { rating, text } }
           relatedProducts { name, price { value } }
       }
   }
   

2. Mobile Applications

   • Reduce bandwidth
   • Precise data fetching
   • Single request

3. Multiple Frontends

   # Web: Full product data
   query { product(sku: "123") { name, price, description, images } }
   
   # Mobile: Minimal data
   query { product(sku: "123") { name, price } }
   

4. Real-time Updates

   subscription {
       orderStatusChanged(orderId: 123) {
           status
           updatedAt
       }
   }
   

5. Microservices

   • Single endpoint
   • Aggregate multiple services
   • Flexible queries

GraphQL Best Practices

# Use variables for parameters
query GetProduct($sku: String!) {
    product(sku: $sku) {
        name
        price { value }
    }
}

# Use fragments for reusable fields
fragment ProductFields on Product {
    name
    sku
    price { value }
}

# Limit query depth
query {
    product(sku: "123") {
        name
        category { name }
    }
}