Load Balancer, Reverse Proxy, and API Gateway

When building modern applications, you'll often encounter terms like Load Balancer, Reverse Proxy, and API Gateway. While these components share some similarities and are sometimes used interchangeably, they serve distinct purposes in system architecture. Understanding their differences is crucial for designing robust, scalable applications.

Load Balancer

What is a Load Balancer?

A Load Balancer is a network device or software that distributes incoming network traffic across multiple servers. Its primary goal is to ensure no single server bears too much load, thereby improving responsiveness and availability of applications.

How It Works

Load balancers act as a traffic cop sitting in front of your servers and routing client requests across all servers capable of fulfilling those requests. They maximize speed and capacity utilization while ensuring that no server is overworked.

Client Request → Load Balancer → Server 1
                              → Server 2
                              → Server 3

Load Balancing Algorithms

Different algorithms determine how traffic is distributed:

1. Round Robin

Distributes requests sequentially across the server pool.

# Simplified Round Robin implementation
class RoundRobinLoadBalancer:
    def __init__(self, servers):
        self.servers = servers
        self.current = 0
    
    def get_next_server(self):
        server = self.servers[self.current]
        self.current = (self.current + 1) % len(self.servers)
        return server

# Usage
lb = RoundRobinLoadBalancer(['server1', 'server2', 'server3'])
print(lb.get_next_server())  # server1
print(lb.get_next_server())  # server2
print(lb.get_next_server())  # server3
print(lb.get_next_server())  # server1 (cycles back)

2. Least Connections

Directs traffic to the server with the fewest active connections.

class LeastConnectionsLoadBalancer:
    def __init__(self, servers):
        self.servers = {server: 0 for server in servers}
    
    def get_next_server(self):
        return min(self.servers.items(), key=lambda x: x[1])[0]
    
    def increment_connection(self, server):
        self.servers[server] += 1
    
    def decrement_connection(self, server):
        self.servers[server] -= 1

3. IP Hash

Uses the client's IP address to determine which server receives the request, ensuring the same client always connects to the same server.

import hashlib

class IPHashLoadBalancer:
    def __init__(self, servers):
        self.servers = servers
    
    def get_server(self, client_ip):
        hash_value = int(hashlib.md5(client_ip.encode()).hexdigest(), 16)
        return self.servers[hash_value % len(self.servers)]

# Usage
lb = IPHashLoadBalancer(['server1', 'server2', 'server3'])
print(lb.get_server('192.168.1.100'))  # Always routes to same server

4. Weighted Round Robin

Similar to Round Robin but assigns weights to servers based on their capacity.

Health Checks

Load balancers continuously monitor the health of backend servers:

import requests
from typing import List, Dict

class HealthCheckLoadBalancer:
    def __init__(self, servers: List[str], health_check_path: str = '/health'):
        self.servers = servers
        self.health_check_path = health_check_path
        self.healthy_servers = []
        self.current = 0
    
    def check_health(self):
        self.healthy_servers = []
        for server in self.servers:
            try:
                response = requests.get(f"{server}{self.health_check_path}", timeout=2)
                if response.status_code == 200:
                    self.healthy_servers.append(server)
            except requests.exceptions.RequestException:
                print(f"Server {server} is unhealthy")
    
    def get_next_server(self):
        if not self.healthy_servers:
            raise Exception("No healthy servers available")
        
        server = self.healthy_servers[self.current]
        self.current = (self.current + 1) % len(self.healthy_servers)
        return server

Configuration Example: NGINX as Load Balancer

http {
    upstream backend {
        # Load balancing method
        least_conn;
        
        # Backend servers
        server backend1.example.com:8080 weight=3;
        server backend2.example.com:8080 weight=2;
        server backend3.example.com:8080 weight=1;
        
        # Health check configuration
        server backend4.example.com:8080 max_fails=3 fail_timeout=30s;
    }
    
    server {
        listen 80;
        
        location / {
            proxy_pass http://backend;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
        }
    }
}

Reverse Proxy

What is a Reverse Proxy?

A Reverse Proxy sits between clients and backend servers, forwarding client requests to the appropriate server and returning the server's response to the client. Unlike a forward proxy (which acts on behalf of clients), a reverse proxy acts on behalf of servers.

How It Works

From the client's perspective, they're communicating directly with the reverse proxy, which appears as the actual server. The reverse proxy then forwards requests to one or more backend servers.

Client → Reverse Proxy → Backend Server(s)
       ←                ←

Key Features

1. SSL/TLS Termination

Handle SSL/TLS encryption/decryption at the proxy level:

server {
    listen 443 ssl;
    server_name example.com;
    
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;
    
    location / {
        # Forward to backend over HTTP (no SSL overhead)
        proxy_pass http://backend:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

2. Caching

Cache responses to reduce load on backend servers:

proxy_cache_path /data/nginx/cache levels=1:2 keys_zone=my_cache:10m 
                 max_size=10g inactive=60m use_temp_path=off;

server {
    location / {
        proxy_cache my_cache;
        proxy_cache_valid 200 60m;
        proxy_cache_valid 404 10m;
        proxy_cache_use_stale error timeout http_500 http_502 http_503;
        
        proxy_pass http://backend;
        add_header X-Cache-Status $upstream_cache_status;
    }
}

3. Request/Response Manipulation

Modify headers, rewrite URLs, or filter content:

location /api/ {
    # Remove /api prefix before forwarding
    rewrite ^/api/(.*)$ /$1 break;
    
    proxy_pass http://backend;
    
    # Add custom headers
    proxy_set_header X-Custom-Header "Value";
    
    # Remove headers
    proxy_hide_header X-Powered-By;
    
    # Add CORS headers
    add_header Access-Control-Allow-Origin *;
}

4. Compression

Compress responses to reduce bandwidth:

gzip on;
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_types text/plain text/css text/xml text/javascript 
           application/json application/javascript application/xml+rss;

location / {
    proxy_pass http://backend;
}

Python Example: Simple Reverse Proxy

from flask import Flask, request, Response
import requests

app = Flask(__name__)

BACKEND_URL = "http://backend-server:8080"

@app.route('/', defaults={'path': ''})
@app.route('/<path:path>', methods=['GET', 'POST', 'PUT', 'DELETE'])
def proxy(path):
    # Build the target URL
    url = f"{BACKEND_URL}/{path}"
    
    # Forward the request
    if request.method == 'GET':
        resp = requests.get(url, params=request.args)
    elif request.method == 'POST':
        resp = requests.post(url, json=request.get_json())
    elif request.method == 'PUT':
        resp = requests.put(url, json=request.get_json())
    elif request.method == 'DELETE':
        resp = requests.delete(url)
    
    # Return the response
    return Response(
        resp.content,
        status=resp.status_code,
        headers=dict(resp.headers)
    )

if __name__ == '__main__':
    app.run(port=80)

API Gateway

What is an API Gateway?

An API Gateway is a more sophisticated component that acts as a single entry point for all client requests to backend microservices. It provides advanced features beyond simple proxying, including authentication, rate limiting, request transformation, and service orchestration.

How It Works

The API Gateway receives requests from clients, processes them (authentication, validation, transformation), routes them to appropriate microservices, aggregates responses, and returns them to the client.

Client → API Gateway → Authentication
                    → Rate Limiting
                    → Request Transformation
                    → Service 1 (User Service)
                    → Service 2 (Order Service)
                    → Service 3 (Payment Service)
                    → Response Aggregation
       ← 

Key Features

1. Authentication & Authorization

Centralized authentication for all backend services:

from fastapi import FastAPI, HTTPException, Depends, Header
from typing import Optional
import jwt

app = FastAPI()

SECRET_KEY = "your-secret-key"

def verify_token(authorization: Optional[str] = Header(None)):
    if not authorization:
        raise HTTPException(status_code=401, detail="Missing authorization header")
    
    try:
        token = authorization.split(" ")[1]  # Bearer <token>
        payload = jwt.decode(token, SECRET_KEY, algorithms=["HS256"])
        return payload
    except jwt.InvalidTokenError:
        raise HTTPException(status_code=401, detail="Invalid token")

@app.get("/api/protected")
async def protected_route(user=Depends(verify_token)):
    return {"message": f"Hello {user['username']}", "user": user}

2. Rate Limiting

Control request rates to prevent abuse:

from fastapi import FastAPI, HTTPException
from datetime import datetime, timedelta
from collections import defaultdict

app = FastAPI()

# Simple in-memory rate limiter
rate_limit_store = defaultdict(list)
RATE_LIMIT = 100  # requests
TIME_WINDOW = 60  # seconds

def check_rate_limit(client_ip: str):
    now = datetime.now()
    # Remove old requests outside time window
    rate_limit_store[client_ip] = [
        timestamp for timestamp in rate_limit_store[client_ip]
        if now - timestamp < timedelta(seconds=TIME_WINDOW)
    ]
    
    # Check if limit exceeded
    if len(rate_limit_store[client_ip]) >= RATE_LIMIT:
        raise HTTPException(
            status_code=429,
            detail="Rate limit exceeded"
        )
    
    # Add current request
    rate_limit_store[client_ip].append(now)

@app.middleware("http")
async def rate_limit_middleware(request, call_next):
    client_ip = request.client.host
    check_rate_limit(client_ip)
    response = await call_next(request)
    return response

3. Request/Response Transformation

Transform data between client and service formats:

from fastapi import FastAPI
from pydantic import BaseModel
import httpx

app = FastAPI()

class ClientRequest(BaseModel):
    user_name: str
    user_email: str

class ServiceRequest(BaseModel):
    username: str
    email: str
    source: str = "api_gateway"

@app.post("/api/users")
async def create_user(client_req: ClientRequest):
    # Transform client request to service format
    service_req = ServiceRequest(
        username=client_req.user_name,
        email=client_req.user_email
    )
    
    # Forward to microservice
    async with httpx.AsyncClient() as client:
        response = await client.post(
            "http://user-service:8080/users",
            json=service_req.dict()
        )
    
    # Transform service response to client format
    service_data = response.json()
    return {
        "id": service_data["id"],
        "name": service_data["username"],
        "email": service_data["email"]
    }

4. Service Orchestration

Aggregate data from multiple services:

from fastapi import FastAPI
import httpx
import asyncio

app = FastAPI()

@app.get("/api/user-dashboard/{user_id}")
async def get_user_dashboard(user_id: str):
    async with httpx.AsyncClient() as client:
        # Make parallel requests to multiple services
        user_task = client.get(f"http://user-service/users/{user_id}")
        orders_task = client.get(f"http://order-service/users/{user_id}/orders")
        recommendations_task = client.get(
            f"http://recommendation-service/users/{user_id}/recommendations"
        )
        
        # Wait for all responses
        user_resp, orders_resp, recommendations_resp = await asyncio.gather(
            user_task, orders_task, recommendations_task
        )
        
        # Aggregate responses
        return {
            "user": user_resp.json(),
            "recent_orders": orders_resp.json()[:5],
            "recommendations": recommendations_resp.json()
        }

5. Protocol Translation

Convert between different protocols (REST to gRPC, GraphQL, etc.):

from fastapi import FastAPI
import grpc
# Import generated protocol buffer modules
# Generated from: user_service.proto
# import user_service_pb2
# import user_service_pb2_grpc

app = FastAPI()

@app.get("/api/users/{user_id}")
async def get_user(user_id: str):
    # REST API Gateway translates to gRPC call
    # Note: Requires protobuf definitions and generated Python files
    # with grpc.insecure_channel('user-service:50051') as channel:
    #     stub = user_service_pb2_grpc.UserServiceStub(channel)
    #     response = stub.GetUser(
    #         user_service_pb2.GetUserRequest(user_id=user_id)
    #     )
    #     
    #     # Convert gRPC response to JSON
    #     return {
    #         "id": response.id,
    #         "name": response.name,
    #         "email": response.email
    #     }
    
    # Simplified example for demonstration
    return {
        "id": user_id,
        "name": "Example User",
        "email": "user@example.com"
    }

Complete API Gateway Example

from fastapi import FastAPI, HTTPException, Depends, Header, Request
from fastapi.responses import JSONResponse
from datetime import datetime, timedelta
from collections import defaultdict
import asyncio
import httpx
import jwt
import time

app = FastAPI(title="API Gateway")

# Configuration
SECRET_KEY = "your-secret-key"
RATE_LIMIT = 100
TIME_WINDOW = 60

# Rate limiting store
rate_limit_store = defaultdict(list)

# Service URLs
SERVICES = {
    "user": "http://user-service:8080",
    "order": "http://order-service:8080",
    "product": "http://product-service:8080"
}

# Authentication
def verify_token(authorization: str = Header(None)):
    if not authorization:
        raise HTTPException(status_code=401, detail="Missing authorization")
    
    try:
        token = authorization.split(" ")[1]
        return jwt.decode(token, SECRET_KEY, algorithms=["HS256"])
    except:
        raise HTTPException(status_code=401, detail="Invalid token")

# Rate limiting
def check_rate_limit(client_ip: str):
    now = datetime.now()
    rate_limit_store[client_ip] = [
        ts for ts in rate_limit_store[client_ip]
        if now - ts < timedelta(seconds=TIME_WINDOW)
    ]
    
    if len(rate_limit_store[client_ip]) >= RATE_LIMIT:
        raise HTTPException(status_code=429, detail="Rate limit exceeded")
    
    rate_limit_store[client_ip].append(now)

# Middleware for logging and monitoring
@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    start_time = time.time()
    
    # Rate limiting
    check_rate_limit(request.client.host)
    
    response = await call_next(request)
    
    process_time = time.time() - start_time
    response.headers["X-Process-Time"] = str(process_time)
    
    # Log request
    print(f"{request.method} {request.url.path} - {response.status_code} - {process_time:.2f}s")
    
    return response

# Routes
@app.get("/api/users/{user_id}")
async def get_user(user_id: str, user=Depends(verify_token)):
    async with httpx.AsyncClient() as client:
        response = await client.get(f"{SERVICES['user']}/users/{user_id}")
        return response.json()

@app.get("/api/orders/{order_id}")
async def get_order(order_id: str, user=Depends(verify_token)):
    async with httpx.AsyncClient() as client:
        response = await client.get(f"{SERVICES['order']}/orders/{order_id}")
        return response.json()

@app.get("/api/dashboard/{user_id}")
async def get_dashboard(user_id: str, user=Depends(verify_token)):
    async with httpx.AsyncClient() as client:
        # Orchestrate multiple service calls
        user_data, orders, products = await asyncio.gather(
            client.get(f"{SERVICES['user']}/users/{user_id}"),
            client.get(f"{SERVICES['order']}/users/{user_id}/orders"),
            client.get(f"{SERVICES['product']}/recommended/{user_id}")
        )
        
        return {
            "user": user_data.json(),
            "recent_orders": orders.json(),
            "recommended_products": products.json()
        }

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)

Comparison: Load Balancer vs Reverse Proxy vs API Gateway

Feature Comparison

Feature	Load Balancer	Reverse Proxy	API Gateway
Primary Purpose	Distribute traffic across servers	Forward requests, handle SSL	Single entry point for APIs
Traffic Distribution	✅ Yes	❌ No (single backend)	✅ Yes (to microservices)
SSL Termination	✅ Yes	✅ Yes	✅ Yes
Caching	❌ Limited	✅ Yes	✅ Yes
Health Checks	✅ Yes	✅ Yes	✅ Yes
Authentication	❌ No	❌ No	✅ Yes
Rate Limiting	❌ Limited	❌ Limited	✅ Yes
Request Transformation	❌ No	✅ Limited	✅ Yes
Service Orchestration	❌ No	❌ No	✅ Yes
Protocol Translation	❌ No	❌ No	✅ Yes
API Analytics	❌ No	❌ No	✅ Yes
API Versioning	❌ No	❌ No	✅ Yes

Key Differences

1. Scope of Functionality

Load Balancer: Focused solely on distributing traffic and ensuring availability
Reverse Proxy: Adds caching, SSL termination, and request/response manipulation
API Gateway: Comprehensive API management with authentication, rate limiting, and orchestration

2. Complexity

Load Balancer: Simple configuration, easy to set up
Reverse Proxy: Moderate complexity, more configuration options
API Gateway: High complexity, extensive configuration and customization

3. Use in Architecture

Load Balancer: Can be used independently or with other components
Reverse Proxy: Often used as part of web server infrastructure
API Gateway: Essential component in microservices architecture

4. Performance Overhead

Load Balancer: Minimal overhead (simple routing)
     ↓
Reverse Proxy: Low overhead (caching can improve performance)
     ↓
API Gateway: Higher overhead (many features, transformations)

Use Cases

When to Use a Load Balancer

High-Traffic Web Applications
- Multiple identical web servers
- Need to distribute load evenly
- Simple horizontal scaling

# Example: E-commerce website with multiple backend servers
upstream web_backend {
    least_conn;
    server web1.example.com:8080;
    server web2.example.com:8080;
    server web3.example.com:8080;
    server web4.example.com:8080;
}

Database Read Replicas
- Distribute read queries across replicas
- Master for writes, replicas for reads
Session-based Applications
- Use sticky sessions (session affinity)
- Ensure users connect to same server

upstream app_backend {
    ip_hash;  # Sticky sessions based on IP
    server app1.example.com:8080;
    server app2.example.com:8080;
}

When to Use a Reverse Proxy

SSL/TLS Termination
- Handle SSL at proxy level
- Reduce load on backend servers
- Centralized certificate management
Static Content Caching
- Cache images, CSS, JavaScript
- Reduce backend server load
- Improve response times

location ~* \.(jpg|jpeg|png|gif|css|js)$ {
    proxy_cache my_cache;
    proxy_cache_valid 200 1d;
    proxy_pass http://backend;
}

Security and Anonymity
- Hide backend server details
- Add security headers
- Filter malicious requests

location / {
    proxy_pass http://backend;
    
    # Security headers
    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-Content-Type-Options "nosniff";
    add_header X-XSS-Protection "1; mode=block";
    
    # Hide server information
    proxy_hide_header X-Powered-By;
    proxy_hide_header Server;
}

Legacy Application Modernization
- Add modern features without modifying legacy code
- URL rewriting
- Header manipulation

When to Use an API Gateway

Microservices Architecture
- Single entry point for multiple services
- Service discovery and routing
- Centralized authentication

# Example: E-commerce microservices
services:
  - user-service: http://users.internal:8080
  - product-service: http://products.internal:8080
  - order-service: http://orders.internal:8080
  - payment-service: http://payments.internal:8080
  - notification-service: http://notifications.internal:8080

routes:
  - path: /api/users/*
    service: user-service
  - path: /api/products/*
    service: product-service
  - path: /api/orders/*
    service: order-service

API Monetization
- Rate limiting per customer tier
- Usage tracking and billing
- API key management

# Different rate limits based on subscription tier
RATE_LIMITS = {
    "free": 100,      # 100 requests per hour
    "basic": 1000,    # 1000 requests per hour
    "premium": 10000  # 10000 requests per hour
}

def get_rate_limit(api_key):
    tier = get_subscription_tier(api_key)
    return RATE_LIMITS.get(tier, RATE_LIMITS["free"])

Mobile and Web Application Backend
- Different response formats for different clients
- Backend For Frontend (BFF) pattern
- Reduce number of client requests

@app.get("/api/mobile/home")
async def mobile_home():
    # Optimized for mobile - minimal data
    return {
        "featured_products": products[:5],
        "categories": categories[:3]
    }

@app.get("/api/web/home")
async def web_home():
    # Full data for web
    return {
        "featured_products": products[:20],
        "categories": categories,
        "banners": banners,
        "recommendations": recommendations
    }

Third-Party API Integration
- Aggregate multiple external APIs
- Standardize response formats
- Cache external API responses
Cross-Cutting Concerns
- Centralized logging and monitoring
- Request/response validation
- Error handling and retry logic

Combining Components

In production systems, these components are often used together:

Example Architecture 1: High-Traffic Web Application

Internet
   ↓
Load Balancer (Layer 4 - TCP)
   ↓
Reverse Proxy (NGINX - SSL Termination, Caching)
   ↓
Application Servers

Example Architecture 2: Microservices with API Gateway

Internet
   ↓
Load Balancer (Distribute to API Gateway instances)
   ↓
API Gateway (Authentication, Rate Limiting)
   ↓
Internal Load Balancers (Per service)
   ↓
Microservices

Example Architecture 3: Enterprise Setup

Internet
   ↓
CDN (Static content)
   ↓
DDoS Protection
   ↓
Load Balancer (AWS ELB)
   ↓
API Gateway (Kong/AWS API Gateway)
   ├→ Reverse Proxy → User Service
   ├→ Reverse Proxy → Order Service
   ├→ Reverse Proxy → Payment Service
   └→ Reverse Proxy → Notification Service

Configuration Example: Combined Setup

# docker-compose.yml example
version: '3.8'

services:
  # Load Balancer
  load-balancer:
    image: haproxy:latest
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg
    depends_on:
      - api-gateway-1
      - api-gateway-2

  # API Gateway instances (scaled)
  api-gateway-1:
    image: kong:latest
    environment:
      KONG_DATABASE: postgres
      KONG_PG_HOST: postgres
    depends_on:
      - postgres

  api-gateway-2:
    image: kong:latest
    environment:
      KONG_DATABASE: postgres
      KONG_PG_HOST: postgres
    depends_on:
      - postgres

  # Backend Services with Reverse Proxy
  user-service:
    image: user-service:latest
    
  user-proxy:
    image: nginx:latest
    volumes:
      - ./nginx-user.conf:/etc/nginx/nginx.conf
    depends_on:
      - user-service

Best Practices

Load Balancer Best Practices

Implement Health Checks
- Regular health checks on all backend servers
- Automatic removal of unhealthy servers
- Graceful degradation
Use Appropriate Algorithm
- Round Robin for uniform servers
- Least Connections for varying workloads
- IP Hash for session persistence
Monitor Performance
- Track response times
- Monitor connection counts
- Alert on failures

Reverse Proxy Best Practices

SSL/TLS Configuration
- Use strong cipher suites
- Enable HTTP/2
- Implement HSTS
Caching Strategy
- Cache static content aggressively
- Use appropriate cache headers
- Implement cache invalidation
Security Headers
- Add security headers
- Hide server information
- Implement rate limiting

API Gateway Best Practices

Authentication Strategy
- Use JWT tokens
- Implement OAuth 2.0
- Short token expiration times
Rate Limiting
- Different limits for different endpoints
- Consider user tiers
- Provide clear error messages
Monitoring and Logging
- Log all requests
- Track API usage
- Monitor performance metrics
Versioning
- Version your APIs
- Support multiple versions
- Clear deprecation strategy

Key Takeaways

Load Balancer: Use when you need to distribute traffic across multiple identical servers
Reverse Proxy: Use when you need SSL termination, caching, and request/response manipulation
API Gateway: Use in microservices architecture when you need comprehensive API management

Remember: These components are not mutually exclusive. They can and often should be used together to build robust, scalable systems.

Conclusion

Understanding the differences between Load Balancers, Reverse Proxies, and API Gateways is essential for designing modern application architectures. While they share some overlapping functionality, each serves a distinct purpose:

Load Balancers excel at distributing traffic and ensuring high availability
Reverse Proxies provide SSL termination, caching, and security features
API Gateways offer comprehensive API management for microservices architectures

Choosing the right component—or combination of components—depends on your specific requirements, architecture, and scale. Start simple and add complexity as needed, always keeping your system's scalability, security, and maintainability in mind.

Load Balancer​

What is a Load Balancer?​

How It Works​

Load Balancing Algorithms​

1. Round Robin​

2. Least Connections​

3. IP Hash​

4. Weighted Round Robin​

Health Checks​

Popular Load Balancer Solutions​

Configuration Example: NGINX as Load Balancer​

Reverse Proxy​

What is a Reverse Proxy?​

How It Works​

Key Features​

1. SSL/TLS Termination​

2. Caching​

3. Request/Response Manipulation​

4. Compression​

Popular Reverse Proxy Solutions​

Python Example: Simple Reverse Proxy​

API Gateway​

What is an API Gateway?​

How It Works​

Key Features​

1. Authentication & Authorization​

2. Rate Limiting​

3. Request/Response Transformation​

4. Service Orchestration​

5. Protocol Translation​

Popular API Gateway Solutions​

Complete API Gateway Example​

Comparison: Load Balancer vs Reverse Proxy vs API Gateway​

Feature Comparison​

Key Differences​

1. Scope of Functionality​

2. Complexity​

3. Use in Architecture​

4. Performance Overhead​

Use Cases​

When to Use a Load Balancer​

When to Use a Reverse Proxy​

When to Use an API Gateway​

Combining Components​

Example Architecture 1: High-Traffic Web Application​

Example Architecture 2: Microservices with API Gateway​

Example Architecture 3: Enterprise Setup​

Configuration Example: Combined Setup​

Best Practices​

Load Balancer Best Practices​

Reverse Proxy Best Practices​

API Gateway Best Practices​

Conclusion​

Additional Resources​

Load Balancer

What is a Load Balancer?

How It Works

Load Balancing Algorithms

1. Round Robin

2. Least Connections

3. IP Hash

4. Weighted Round Robin

Health Checks

Popular Load Balancer Solutions

Configuration Example: NGINX as Load Balancer

Reverse Proxy

What is a Reverse Proxy?

How It Works

Key Features

1. SSL/TLS Termination

2. Caching

3. Request/Response Manipulation

4. Compression

Popular Reverse Proxy Solutions

Python Example: Simple Reverse Proxy

API Gateway

What is an API Gateway?

How It Works

Key Features

1. Authentication & Authorization

2. Rate Limiting

3. Request/Response Transformation

4. Service Orchestration

5. Protocol Translation

Popular API Gateway Solutions

Complete API Gateway Example

Comparison: Load Balancer vs Reverse Proxy vs API Gateway

Feature Comparison

Key Differences

1. Scope of Functionality

2. Complexity

3. Use in Architecture

4. Performance Overhead

Use Cases

When to Use a Load Balancer

When to Use a Reverse Proxy

When to Use an API Gateway

Combining Components

Example Architecture 1: High-Traffic Web Application

Example Architecture 2: Microservices with API Gateway

Example Architecture 3: Enterprise Setup

Configuration Example: Combined Setup

Best Practices

Load Balancer Best Practices

Reverse Proxy Best Practices

API Gateway Best Practices

Conclusion

Additional Resources