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Book II · Status window, Japan and system design

Reincarnated as an Engineer

The Red-Robed Mage-Engineer Doesn’t Chant: All My Spells Come Precompiled

Chapter 1

A New Life, the Whole Stack

I woke up in a world with a status window and a calling: build the whole thing. Screens, APIs, services and the databases underneath, all from one desk. Native apps came along too, as a side quest.

Chapter 2

Every Wish Starts as a Circle

Clients arrive with a wish, not a specification. Before any code, I draw the system: who calls whom, where the data lives and what must never go down. Only then does the transmutation begin.

Interlude

The Transmutation Circle

Pick a wish, see the circle that would grant it, then follow one request through it.

A simplified sketch, not a production blueprint.

Choose a wish

A shop that survives a big sale day

Busy pages are answered from the cache's memory, and extra copies of the shop take the rest of the traffic.

The price: Pages may be a few seconds out of date.

Press Transmute to follow one request.Every step is listed on the scroll.

Outer ring: the apps that ask. Second ring: the edge and the gateway. Inner ring: every service, including the cache, queue, worker and sign-in. Centre: the databases.

  • CDN edge: Serves pictures and pages from a place near the shopper.
  • Cache: Busy pages are served from memory.
  • Shop ×3: Three copies of the shop service take the rest of the traffic.
  • Orders: Records each purchase.
  • Read replica: A copy of the database that answers reads.
  1. A shopper on the phone asks for the sale page; it reaches the CDN edge first.
  2. The edge passes it on to the gateway.
  3. The gateway asks the cache. On a miss, the shop reads the replica.
  4. Cache hit: the page is already in memory, so it turns back here.
  5. The page goes back out through the edge.
  6. The shopper sees the page on the phone.
  7. Result: Busy page served from memory.

Chapter 3

Four Tongues, One Quest

Turkish is my native language. Japanese is at JLPT N1, and I read light novels in it. English sits at C1. German is at A2, and the training is still in progress.