WeApRous Project - HTTP Server & Reverse Proxy Implementation

Status Update: November 6, 2025

📋 Project Overview

This project implements a complete HTTP server with cookie-based authentication and a reverse proxy server with load balancing capabilities. The implementation consists of modular components that can work independently or together to provide web serving and proxying functionality.

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✅ Task 1: HTTP Cookie Base + Proxy (COMPLETED)

🌟 Key Features Implemented

1. HTTP Server with Cookie Authentication

• Multi-threaded Request Handling: Each client connection runs in a separate daemon thread
• Cookie-based Session Management: Parse and validate authentication cookies
• POST/GET Request Processing: Full HTTP protocol support with proper body parsing
• Static File Serving: Serve HTML, CSS, JavaScript, and image files
• Authentication Flow: Login endpoint with credential validation

2. Reverse Proxy Server

• Request Forwarding: Route incoming requests to backend servers
• Load Balancing Policies:
  • Round-robin distribution
  • Least-connections routing
  • IP-hash for session affinity
• Multiple Backend Support: Configure multiple upstream servers
• Host-based Routing: Route based on Host header values

3. Modular Architecture

• HTTP Protocol Layer: Generic HTTP processing (httpadapter, request, response)
• Application Logic Layer: User-defined business logic in separate applications
• Daemon Infrastructure: Backend server management and client handling

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🏗️ Architecture & File Structure

Core Infrastructure (daemon/ folder)

File	Purpose	Responsibility
backend.py	HTTP server daemon	Accept connections, spawn threads
httpadapter.py	HTTP protocol adapter	Parse requests, route to handlers
request.py	HTTP request processing	Parse headers, body, cookies
response.py	HTTP response building	Generate HTTP responses, handle static files
proxy.py	Reverse proxy implementation	Forward requests, load balancing

Application Implementations

File	Purpose	Framework Used
session_base_http_server.py	Manual Route Management	Direct daemon usage
start_sampleapp_new.py	WeApRous Framework	Uses @route decorators

Server Entry Points

File	Purpose	Port
start_backend.py	HTTP server startup	9000
start_proxy.py	Proxy server startup	8080

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🔧 Technical Implementation Details

Handler Function Signature

Current Implementation: Single parameter approach

@app.route('/login', methods=['POST'])
def login(req):  # ✅ Current: Pass request object
    headers = req.headers
    body = req.body
    cookies = req.cookies

Original Design: Two parameter approach (deprecated)

def login(headers="guest", body="anonymous"):  # ❌ Original design

Rationale: Single parameter provides better access to full request context and follows modern web framework patterns.

Application Logic Separation

Method 1: Manual Implementation (session_base_http_server.py)

# Manual route registration
routes = {
    ('GET', '/'): route_index,
    ('POST', '/login'): route_login,
    ('GET', '/login.html'): route_login_page
}

# Direct daemon usage
daemon = WeApRous()
daemon.create_backend('127.0.0.1', 9000, routes)

Method 2: Framework-based (start_sampleapp_new.py)

# Automatic route registration via decorators
@app.route('/login', methods=['POST'])
def login(req):
    return handle_login_logic(req)

# WeApRous framework manages registration
app.run('127.0.0.1', 9000)

Proxy Configuration (config/proxy.conf)

# Single backend routing
host "127.0.0.1:8080" {
    proxy_pass http://127.0.0.1:9000;
}

# Load balancing with multiple backends
host "app2.local" {
    proxy_pass http://192.168.56.210:9002;
    proxy_pass http://192.168.56.220:9002;
    dist_policy round-robin
}

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🚀 How to Run

1. HTTP Server with Session-Based Cookie Authentication (Recommended)

# Terminal 1: Start HTTP server with session-based authentication
python ./session_base_http_server.py

# This will start the server on 127.0.0.1:9000 with the following routes:
# - GET /login        - Login page
# - POST /login       - Handle login authentication  
# - GET /login.html   - Login form
# - GET /logout       - Logout functionality
# - GET /            - Main page (requires authentication)
# - GET /index.html   - Index page (requires authentication)

# Access directly: http://127.0.0.1:9000/

2. HTTP Server + Proxy (Full Setup)

# Terminal 1: Start HTTP server with session authentication
python ./session_base_http_server.py

# Terminal 2: Start proxy server  
python ./start_proxy.py --server-ip 127.0.0.1 --server-port 8080

# Access via proxy: http://127.0.0.1:8080/
# Proxy forwards requests to backend (port 9000)
# This demonstrates the complete reverse proxy functionality

3. Load Balancing Setup (Advanced)

# Terminal 1-3: Start multiple HTTP servers with session auth
python session_base_http_server.py  # Will run on port 9000
# Note: Modify port in session_base_http_server.py for multiple instances

# Terminal 4: Start proxy (configure proxy.conf first)
python start_proxy.py --server-ip 127.0.0.1 --server-port 8080

📹 Demo Video

For a complete step-by-step demonstration of the authentication and proxy functionality, see: DemoTask1_compressed.mp4 - Shows the complete login flow, cookie authentication, and proxy routing in action (compressed version for GitHub compatibility).

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🧪 Testing

Automated Test Suite

# Run all tests
cd test/
python run_all_test.py

# Run individual tests
python test_proxy.py           # Proxy routing tests
python test_authentication.py  # Cookie authentication tests  
python quick_test.py          # Basic functionality test
python test_file_read.py      # File operations test

Manual Testing

1. Authentication Flow: Access /, login with admin/password, verify cookie persistence
2. Proxy Routing: Compare responses from :9000 vs :8080
3. Load Balancing: Send multiple requests, observe backend selection

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📊 Test Results Status

Test File	Status	Purpose
quick_test.py	✅ PASSED	Basic HTTP request/response
test_file_read.py	✅ PASSED	Static file serving
test_proxy.py	⚠️ PARTIAL	Proxy routing (needs running servers)
test_authentication.py	⚠️ PARTIAL	Cookie auth (needs running servers)

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🔄 Load Balancing Policies

Round-Robin

• Behavior: Distribute requests sequentially across backends
• Use Case: Equal load distribution for similar backend capacities
• Implementation: Global counter per hostname

Least-Connections

• Behavior: Route to backend with fewest active connections
• Use Case: Varying request processing times
• Implementation: Track active connections per backend

IP-Hash

• Behavior: Consistent routing based on client IP hash
• Use Case: Session affinity requirements
• Implementation: MD5 hash of client IP modulo backend count

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📝 Development Notes

Current Status

✅ Completed: Basic HTTP server with cookie authentication
✅ Completed: Reverse proxy with load balancing
✅ Completed: Modular architecture with clean separation
⚠️ In Progress: Additional test cases for complex scenarios
⚠️ Pending: Comprehensive documentation and reports

Next Steps for Task 2

• Utilize start_sampleapp_new.py (WeApRous framework approach)
• Leverage @route decorators for automatic handler registration
• Build upon existing daemon infrastructure
• Extend load balancing policies as needed

Known Limitations

• Browser form submissions may require additional debugging vs Postman
• Proxy configuration requires manual host entry management
• Test suite needs running servers for full validation

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🎯 Key Technical Decisions

1. Single Parameter Handler: Chose handler(req) over handler(headers, body) for better extensibility
2. Manual Route Management: Implemented direct route dictionary for fine-grained control
3. Framework Preparation: Created foundation for decorator-based routing in Task 2
4. Modular Design: Separated HTTP protocol handling from application logic
5. Load Balancing: Implemented multiple policies for different use cases

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📚 Usage Examples

Authentication Test

# Test login flow
curl -X POST http://127.0.0.1:8080/login \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "username=admin&password=password"

# Test authenticated access
curl http://127.0.0.1:8080/ \
  -H "Cookie: auth=true"

Proxy Load Balancing

# Send multiple requests to see round-robin
for i in {1..5}; do
  curl http://127.0.0.1:8080/
  echo "Request $i completed"
done

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Project Team: HCMUT - Computer Networks Course
Implementation Period: October 29 - November 6, 2025
Current Phase: Task 1 Complete, Task 2 Preparation

Note: This implementation follows PEP 8 style guidelines and includes comprehensive docstrings as required by the assignment.