APIs

Overview

This section consolidates API-related content across the site: fundamentals, REST design with FastAPI, GraphQL, and enterprise HR system integration (Greenhouse, Workday) with OAuth, retry logic, and rate limiting.

Fundamentals

• Understanding and Implementing APIs — REST, SOAP, GraphQL, gRPC; RESTful principles, status codes, versioning.

REST & FastAPI

• FastAPI for REST APIs — Pydantic validation, async endpoints, OpenAPI docs, OAuth2/JWT.

Flask

• Flask — Overview — Micro-framework design, WSGI, request/response lifecycle, core components, Flask vs FastAPI vs Django.
• Flask — Benefits & Utilization — Flexibility, extension ecosystem, production utilization patterns, performance characteristics.
• Flask — Building REST APIs — Routing, blueprints, validation, error handling, JWT auth, CORS, rate limiting, OpenAPI with Flask-Smorest.
• Flask — Sample Code — Runnable CRUD, JWT, file upload, scikit-learn & PyTorch model serving, Celery, SocketIO, app factory.
• Flask — Production Deployment — Gunicorn, nginx, Docker, Kubernetes, 12-factor config, observability, security hardening, zero-downtime deploys.

GraphQL

• GraphQL — Advanced Technical Details — Schema typing, single endpoint, client-driven queries.

HR Systems Integration

• Greenhouse & Workday API Integration — OAuth, retry/backoff, rate limiting, Medallion ingestion, SCD Type 2, anomaly detection.

YouTube API

• YouTube Search Engine & Brand-Safety Platform — Xapian probabilistic search over a multi-billion-video corpus, BM25 ranking, NLP feature extraction, brand-safety classification, REST API, Cassandra + Kinesis on AWS, Scala & C++.

Common Cross-Cutting Concerns

• Authentication — OAuth 2.0 client-credentials and authorization-code flows; API keys; bearer tokens.
• Rate Limiting — Token-bucket and leaky-bucket strategies; respecting Retry-After headers.
• Retries — Exponential backoff with jitter; circuit breakers; idempotency keys on mutating calls.
• Pagination — Cursor-based, offset-based, and link-header pagination patterns.
• Observability — Structured logging, correlation IDs, latency histograms, error-rate SLOs.
• Schema Evolution — Versioning strategies (URI vs. header), deprecation policies, backward compatibility.