System maps

Engineering Studio

One blueprint covers the full path of a request. When a review needs depth on one zone, I open its focused view: DNS and the edge, runtime and load balancing, storage and coordination, or media processing and fan-out.

DNS to request path

Zoom in on how a domain lookup turns into an edge request with policy checks, request metadata, and response metadata.

  • Mobile / BrowserUser enters the domain and starts the request path.
  • Recursive resolverISP or public resolver checks cache before walking DNS.
  • Root NSReturns the TLD nameserver for .com, .org, or another suffix.
  • TLD NSPoints the resolver toward the authoritative nameserver.
  • Authoritative NSReturns the final record, TTL, and canonical target.
  • Resolved IPIP, CNAME, TTL, DNSSEC state, and cacheability.
  • CDN / EdgeTLS, static asset cache, WAF, bot checks, regional routing.
  • API GatewayValidation, auth handoff, rate limits, routing, metering, dedupe.

Runtime and load balancing

Focus on API gateway handoff, load balancing, frontend servers, CDN edge, backend cluster, dispatcher, and connection state.

  • Security optionsOAuth, WAF rules, TLS policy, CSRF, request signing, replay window.
  • Metrics tapeResponse time, failed status codes, active connections, error message.
  • Load BalancerRound robin, weighted, least connections, hashing, health check.
  • Frontend serversHTTP, WebSocket, SSE, short polling, stream API, live sessions.
  • CDN / Edge serversGlobal static, ABR stream, miss handling, origin fetch, regional cache.
  • Backend clusterCluster of services with microservice boundaries, autoscale, CPU and memory pressure.
  • Message DispatcherRoutes stream chunk messages to the active frontend connection owner.
  • Balancing checklistInput validation, auth, throttling, whitelist, flow control, TLS termination.
  • Connection tableUser, connection object, server ownership, bandwidth, topics.

Storage, cache, and coordination

Inspect backend write stability, distributed IDs, locks, metadata, primary data, shards, replicas, cold storage, and cache policy.

  • Distributed IDUUID, Snowflake, auto increment variants, Baidu UID, Sonyflake.
  • Resource lockingRedis Redlock, Chubby, Zookeeper, lease timeout, lock contention.
  • Concurrency choicesSerial, batch, optimistic, pessimistic, retry, idempotent update.
  • Streaming chunk metadataKey, checksum, timestamp, server, object pointer, retry state.
  • DatabasesRDBMS, column wide, document, key-value, graph, quad tree, time-series.
  • ShardsRange, hash, geographical, directory based, hot node hash.
  • ReplicasQuorum, hinted handoff, Merkle tree, cross-geo, read/write split.
  • Cold storageOld records, consistent hashing, hash rings, archival access.
  • In-memory cacheWrite-through, read-through, write-around, write-back.
  • Distributed cacheCache miss/hit, disk and memory usage, eviction and invalidation.
  • Eviction policyLRU, LFU, FIFO, MRU, random, least-used, on-demand expiration.

Media upload and fan-out

Trace raw object chunks through queue validation, workers, encoded storage, and fan-out services such as notification, search, analytics, and payment charge.

  • Object StorageRaw S3 chunks, multipart upload, object pointer, checksum source.
  • For every chunkCount messages, consumption rate, in-transit, waiting for ack, queue limit.
  • Message QueueBroker, pub/sub, checksum validation, retry, backpressure.
  • Processing WorkersValidate checksum, transcode, scan, compress, rate-limit, push outputs.
  • Processed / Encoded StorageLossless or lossy encoding, object count, compression ratio, failed count.
  • Processing costCompute time, failed count, CPU/disk use, consumed storage, object count.
  • Pub / Sub QueueBrokered topics with retry keys and consumer groups.
  • Notification ServiceSpam controls, stop words, dedupe, retry with idempotent key.
  • Recommendation ServiceContent-based and collaborative filtering.
  • Log ProcessingNormalize logs and publish observability streams.
  • Search ServiceIndex documents and serve query traffic.
  • Analytics ServiceEvents, dashboards, cohorts, conversion, alerting.
  • Payment ChargeIdempotent key, expired cards, insufficient balance, third-party bank.