Project Pitch: RFC 9111 CDN Caching Proxy

30-Second Elevator Pitch

"I engineered 17-CDN-Caching-Proxy, an industrial-grade RFC 9111 compliant reverse caching proxy built with TypeScript and Node.js stream pipelines. Siting at the network edge, it intercepts client requests, executes sub-millisecond cache lookups across in-memory and disk segments, and delivers up to 95% origin bandwidth offload. It solves cache stampedes via atomic request coalescing, handles video streaming with RFC 7233 byte-range slicing, performs on-the-fly streaming Brotli compression, and supports instant Surrogate-Key tag purges with an immutable cryptographic audit trail."

---

2-Minute Technical Interview Pitch

"When scaling high-traffic distributed web systems, uncached traffic creates origin database saturation, massive cloud egress bills, and elevated p99 user latencies.

To solve this, I designed and implemented 17-CDN-Caching-Proxy, a complete RFC 9111 compliant reverse-caching edge proxy paired with a Next.js 14 operational dashboard.

At the core of the proxy in src/proxy/index.ts and src/cache/lookup.ts, incoming requests are parsed and canonicalized into SHA-256 cache keys. The key generator normalizes URL paths, sorts query parameters deterministically, and isolates variant representations using secondary keys calculated from HTTP Vary headers such as Accept-Encoding.

To eliminate catastrophic 'thundering herd' cache stampedes when popular content expires, I developed a Single-Flight Request Coalescer in src/proxy/coalesce.ts. When hundreds of concurrent requests miss the cache for the same resource, the first request is elected leader and dispatched to the upstream origin, while all subsequent requests join an in-flight queue. Once the origin stream arrives, it is fanned out to all waiting clients and piped simultaneously into the cache store using zero-copy stream splitting.

The storage subsystem in src/cache/ features a two-tier architecture: a memory-segmented LRU store bounded by tenant quotas and total byte limits, backed by a persistent disk store with background segment compaction. Freshness is strictly calculated per RFC 9111, honoring s-maxage, max-age, stale-while-revalidate, and conditional HTTP 304 revalidations via ETag and If-None-Match.

For dynamic content invalidation, I built a Surrogate-Key tag index in src/purge/ that invalidates thousands of catalog items within 5 milliseconds, backed by a SHA-256 tamper-evident audit log. The system is validated by 151 Vitest test suites and 1,064 assertions covering protocol edge cases, client socket disconnections, and zero memory leaks under 1,000 consecutive 1 MB requests."