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Open Chat (Slack-style) →Open URL Shortener →

Chat (Slack-style) vs URL Shortener

Chat (Slack-style rooms)

Chat (Slack-style rooms)

Room-based pub/sub fanout across gateway instances.

Components (6)

  • Sender
  • Recipient
  • WS Gateway
  • Chat Service
  • Postgres
  • Redis Pub/Sub

Headline numbers

  • WebSocket connections~10M concurrent
  • Messages / sec~3K avg, ~15K peak
  • Fan-out writes / sec~30K
URL Shortener

URL Shortener

Hashing, key generation, read-heavy caching.

Components (6)

  • Client
  • API Gateway
  • Write Service
  • Read Service
  • Redis
  • Postgres

Headline numbers

  • Write QPS (avg)~1,200/sec
  • Read QPS (avg)~120,000/sec
  • Storage per year~5 TB

Key differences

Only in Chat (Slack-style)
  • Redis Pub/Sub
In both
  • Client
  • Api Gateway
  • Service
  • Database
Only in URL Shortener
  • Redis

Flow shape

Chat (Slack-style) flows
  • Send to a room6 steps
  • Reconnect and catch up4 steps
  • ⚠ Redis Pub/Sub is down5 steps
URL Shortener flows
  • Shorten a URL3 steps
  • Resolve short URL (cache hit)3 steps
  • Resolve short URL (cache miss)4 steps
  • ⚠ Redis is down4 steps