Infrastructure Components

Enterprise Web Infrastructure

Thread/Process-Based (Apache): Creates a new thread/process for each connection. Good for CPU-bound tasks but memory-intensive under high concurrency. Apache HTTP Server Documentation.
Event-Driven (Nginx): Uses a non-blocking, asynchronous event loop. Handles thousands of connections with a single worker process. Ideal for I/O-bound tasks and high concurrency. Nginx Architecture Explained.

Intermediary between client and origin. What is a Reverse Proxy? (Cloudflare).

SSL Termination: Offloads decryption CPU cost from backend servers.
Connection Pooling: Maintains keep-alive connections to backends to reduce TCP handshake overhead.
Buffering: Reads slow client uploads completely before sending to backend (prevents “Slowloris” attacks).

Distributes traffic across backend servers to ensure availability and scalability. What is Load Balancing? (Cloudflare).

L4 Load Balancing (Transport): Decisions based on IP/Port. Fast, packet-level. No visibility into HTTP headers.
L7 Load Balancing (Application): Decisions based on URL, Headers, Cookies. CPU-intensive but smarter (e.g., routing /api to Service A and /static to Service B).
Algorithms:
- Round Robin: Sequential distribution.
- Least Connections: Sends to server with fewest active connections.
- Consistent Hashing: Maps keys (e.g., User ID) to servers; minimizes reshuffling when servers are added/removed.

Edge Caching: Storing static assets (images, CSS, JS) at the network edge (PoPs) to reduce latency and origin load. What is a CDN? (Cloudflare).
Cache-Control: HTTP header controlling cache behavior. Cache-Control (MDN).
- public: Cacheable by anyone (CDN, Browser).
- private: Cacheable only by browser (User-specific data).
- no-store: Never cache.
- s-maxage: TTL for shared caches (CDNs).
Purging: Invalidating cached content before TTL expires (e.g., after a deployment).