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HTTP Server from Scratch - SDE2 Resume Project Plan

🎯 Project Summary (Resume One-Liner)

"Production-grade HTTP/1.1 server built from scratch using raw sockets in Python, featuring async I/O, connection pooling, middleware architecture, and comprehensive test coverage"

✅ Current State

  • Basic TCP socket server with educational documentation
  • Single-threaded, blocking I/O
  • Minimal HTTP response (hardcoded Hello World)

🚀 SDE2-Level Enhancements Roadmap

Phase 1: Core HTTP Protocol Implementation

Feature Description Why SDE2 Cares
HTTP Request Parser Parse method, path, headers, query params, body Shows protocol-level understanding
HTTP Response Builder Proper status codes, headers, chunked encoding RFC compliance
URL Routing Path-based routing with dynamic parameters /users/:id API design skills
Static File Serving Serve files from disk with proper MIME types Real-world utility
Error Handling 400, 404, 405, 500 with proper responses Production readiness

Phase 2: Concurrency & Performance ⭐

Feature Description Why SDE2 Cares
Multi-threading Thread pool for handling concurrent connections Concurrency fundamentals
Async I/O (asyncio) Non-blocking event loop using select/epoll Modern Python expertise
Connection Keep-Alive HTTP/1.1 persistent connections Performance optimization
Request Timeout Configurable timeouts to prevent resource exhaustion Production hardening
Graceful Shutdown Handle SIGTERM/SIGINT properly DevOps awareness

Phase 3: Architecture & Design Patterns ⭐⭐

Feature Description Why SDE2 Cares
Middleware Pipeline Composable request/response handlers Clean architecture
Logging Middleware Structured JSON logging with request IDs Observability
CORS Middleware Cross-origin resource sharing Security awareness
Rate Limiter Token bucket algorithm for request throttling System design
Compression gzip/deflate response compression Optimization skills

Phase 4: Testing & Quality ⭐⭐⭐

Feature Description Why SDE2 Cares
Unit Tests pytest with 80%+ coverage Testing discipline
Integration Tests End-to-end HTTP request/response tests Quality assurance
Load Testing Benchmarks with wrk or ab Performance awareness
Type Hints Full typing with mypy compliance Code quality
Documentation API docs, architecture diagrams Communication skills

Phase 5: Advanced Features (Differentiators)

Feature Description Why SDE2 Cares
WebSocket Support Upgrade handshake, bidirectional comms Protocol expertise
HTTPS/TLS SSL certificate handling Security
HTTP/2 Basics Multiplexing, header compression Modern protocols
Config Management YAML/ENV configuration 12-factor app
Health Checks /health endpoint for monitoring Production systems

📁 Recommended Project Structure

http-server-python/
├── README.md                    # Project overview, badges, quick start
├── pyproject.toml               # Modern Python packaging
├── Makefile                     # Common commands (run, test, lint)
├── Dockerfile                   # Container support
├── docker-compose.yml           # Local development
│
├── src/
│   └── httpserver/
│       ├── __init__.py
│       ├── __main__.py          # Entry point
│       ├── server.py            # Main server class
│       ├── config.py            # Configuration management
│       │
│       ├── core/
│       │   ├── __init__.py
│       │   ├── socket_server.py # Low-level TCP handling
│       │   ├── connection.py    # Connection management
│       │   └── thread_pool.py   # Worker thread pool
│       │
│       ├── http/
│       │   ├── __init__.py
│       │   ├── request.py       # HTTP request parser
│       │   ├── response.py      # HTTP response builder
│       │   ├── router.py        # URL routing
│       │   ├── status_codes.py  # HTTP status enums
│       │   └── mime_types.py    # Content-Type mappings
│       │
│       ├── middleware/
│       │   ├── __init__.py
│       │   ├── base.py          # Middleware interface
│       │   ├── logging.py       # Request logging
│       │   ├── cors.py          # CORS headers
│       │   ├── compression.py   # gzip compression
│       │   └── rate_limit.py    # Rate limiting
│       │
│       └── handlers/
│           ├── __init__.py
│           ├── static.py        # Static file handler
│           └── health.py        # Health check endpoint
│
├── tests/
│   ├── conftest.py              # pytest fixtures
│   ├── unit/
│   │   ├── test_request.py
│   │   ├── test_response.py
│   │   └── test_router.py
│   ├── integration/
│   │   └── test_server.py
│   └── load/
│       └── benchmark.py
│
├── examples/
│   ├── simple_server.py
│   └── api_server.py
│
└── docs/
    ├── architecture.md
    ├── protocol.md
    └── diagrams/
        └── request_flow.png

🏗️ Architecture Diagram

                                    ┌─────────────────────────────────────────────────────────────┐
                                    │                    HTTP Server                               │
                                    └─────────────────────────────────────────────────────────────┘
                                                              │
        ┌─────────────────────────────────────────────────────┼─────────────────────────────────────────────────────┐
        │                                                     │                                                     │
        ▼                                                     ▼                                                     ▼
┌───────────────┐                                   ┌───────────────┐                                   ┌───────────────┐
│  TCP Socket   │                                   │  Thread Pool  │                                   │    Config     │
│    Server     │                                   │   (Workers)   │                                   │   Manager     │
│               │                                   │               │                                   │               │
│ • bind()      │                                   │ • min_workers │                                   │ • host, port  │
│ • listen()   │                                   │ • max_workers │                                   │ • timeout     │
│ • accept()    │                                   │ • queue_size  │                                   │ • log_level   │
└───────────────┘                                   └───────────────┘                                   └───────────────┘
        │
        │  Connection
        ▼
┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                          MIDDLEWARE PIPELINE                                                         │
│                                                                                                                      │
│   ┌─────────────┐    ┌─────────────┐    ┌─────────────┐    ┌─────────────┐    ┌─────────────┐                       │
│   │   Logging   │───►│    CORS     │───►│ Rate Limit  │───►│ Compression │───►│   Router    │                       │
│   │  Middleware │    │  Middleware │    │  Middleware │    │  Middleware │    │             │                       │
│   └─────────────┘    └─────────────┘    └─────────────┘    └─────────────┘    └─────────────┘                       │
│                                                                                       │                              │
└───────────────────────────────────────────────────────────────────────────────────────┼──────────────────────────────┘
                                                                                        │
                              ┌─────────────────────────────────────────────────────────┼─────────────────────────────────┐
                              │                                                         │                                 │
                              ▼                                                         ▼                                 ▼
                      ┌───────────────┐                                         ┌───────────────┐                 ┌───────────────┐
                      │    Static     │                                         │     API       │                 │    Health     │
                      │    Files      │                                         │   Handlers    │                 │    Check      │
                      │               │                                         │               │                 │               │
                      │ GET /static/* │                                         │ GET /api/*    │                 │ GET /health   │
                      └───────────────┘                                         └───────────────┘                 └───────────────┘

📊 Key Metrics to Highlight on Resume

Performance

  • Handles 1000+ concurrent connections
  • <5ms average response latency
  • 10,000+ req/sec throughput (benchmarked with wrk)

Code Quality

  • 85%+ test coverage
  • 0 type errors (mypy strict mode)
  • A rating on code quality tools

Production Features

  • Graceful shutdown with in-flight request completion
  • Structured logging with correlation IDs
  • Container-ready with health checks

🎤 Interview Talking Points

System Design Questions This Project Answers:

  1. "How does HTTP work at the socket level?" → You built it from scratch
  2. "Explain TCP 3-way handshake" → Implemented in your server
  3. "How would you handle 10K concurrent connections?" → Thread pool + event loop
  4. "Design a rate limiter" → Token bucket implementation
  5. "How do you ensure graceful shutdown?" → Signal handling + connection draining

Demonstrates These SDE2 Competencies:

  • ✅ Deep understanding of networking fundamentals
  • ✅ Proficiency in Python async/threading
  • ✅ Clean architecture and SOLID principles
  • ✅ Production mindset (logging, monitoring, error handling)
  • ✅ Testing discipline (unit, integration, load)
  • ✅ Documentation and communication skills

🚦 Implementation Priority (MVP to Production)

Week 1: Core Functionality

  • HTTP request parser (method, path, headers)
  • HTTP response builder with status codes
  • Basic URL router with path matching
  • Static file serving
  • Error responses (404, 500)

Week 2: Concurrency

  • Thread pool implementation
  • Connection timeout handling
  • Keep-alive connections
  • Graceful shutdown (SIGTERM)

Week 3: Middleware & Quality

  • Middleware pipeline architecture
  • Logging middleware (JSON format)
  • Unit tests with pytest (80% coverage)
  • Type hints + mypy

Week 4: Polish & Documentation

  • Integration tests
  • Load testing with benchmarks
  • README with architecture diagrams
  • Dockerfile + docker-compose
  • Example applications

📝 Resume Bullet Points (Copy-Paste Ready)

• Engineered a production-grade HTTP/1.1 server from scratch using Python raw sockets,
  implementing TCP connection handling, request parsing, and response serialization per RFC 7230

• Designed thread pool architecture supporting 1000+ concurrent connections with <5ms
  latency, demonstrating deep understanding of concurrency patterns and resource management

• Built extensible middleware pipeline (logging, CORS, rate limiting, compression) following
  chain-of-responsibility pattern, enabling modular request/response processing

• Achieved 85% test coverage with pytest, including unit tests, integration tests, and
  load testing benchmarks using wrk (10K+ req/sec throughput)

• Implemented production-ready features: graceful shutdown, structured logging with
  correlation IDs, configurable timeouts, and container-ready health checks

🔗 GitHub Repository Enhancements

README Badges to Add:

![Python](https://img.shields.io/badge/python-3.10+-blue)
![Tests](https://img.shields.io/badge/tests-passing-green)
![Coverage](https://img.shields.io/badge/coverage-85%25-green)
![License](https://img.shields.io/badge/license-MIT-blue)

Sections to Include:

  1. Quick Start - 3-line setup
  2. Features - Bullet list with ✅ emojis
  3. Architecture - Diagram from above
  4. Benchmarks - Performance numbers
  5. API Reference - Usage examples
  6. Contributing - Shows collaboration skills

❓ FAQ

Q: Is this better than just using Flask/FastAPI? A: For production, use established frameworks. This project demonstrates you understand what those frameworks do under the hood - a key differentiator for SDE2.

Q: How long will this take? A: MVP (Weeks 1-2) in ~20-30 hours. Full implementation (Weeks 1-4) in ~50-60 hours.

Q: What if I don't finish everything? A: Phase 1-2 alone is resume-worthy. Phase 3+ makes it exceptional.

🎯 Next Steps

  1. Start with HTTP request parser (src/httpserver/http/request.py)
  2. Add basic router (src/httpserver/http/router.py)
  3. Write tests alongside features
  4. Document as you go

Ready to start? Let me know which phase to begin implementing!