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Backend Service Architecture ​

Backend Service Architecture Graphics Coverage ​

Primary chapter graphic: Distributed Counter Service Flow, Secure Delivery Integration Flow, Social App Backend Core Flow. Accepted graphics: 3. Reviewed non-signal pages: 1. Open graphics in review: 0. QA status lives in graphics audit and visual review ledger.

Corpus pages: p. 35, p. 58, p. 89, p. 93, p. 108, p. 263, p. 318, p. 323, p. 353-354 Coverage: 10 pages; low-confidence extraction ranges: p. 318, p. 323, p. 353-354

This chapter is part of Marius's owned architecture build corpus. The text routes decisions; durable implementation signal is carried by accepted graphics, reviewed non-signal decisions, and the linked QA audit.

Chapter Visuals ​

Accepted graphics carry the canonical design signal for this chapter. Each selected source page is either accepted as a graphic or explicitly marked non-signal in the source-faithful ledger. Review and QA state live in visual inventory, visual review ledger, and graphics audit.

Distributed Counter Service Flow ​

Distributed Counter Service Flow

Secure Delivery Integration Flow ​

Secure Delivery Integration Flow

Social App Backend Core Flow ​

Social App Backend Core Flow

Open Review Queue ​

  • none

Reviewed Non-Signal Pages ​

  • Backend Service Architecture: DNS + Topic Map: source p. 108; batch 10; status non-signal/reviewed; ledger reason in visual-review-ledger.json

Use When ​

  • Business capabilities need process boundaries, ownership, and runtime shape.

Avoid When ​

  • The domain is too fluid to split into independent services.

Core Model ​

  • Start with cohesive modules. Split services only when ownership, scale, or reliability needs justify the boundary.
  • Prefer explicit ownership over accidental coupling. Every boundary should say who owns correctness, cost, data, recovery, and change.
  • Use corpus page pointers for inspection, and keep the chapter notes focused on reusable design decisions.

Implementation Guidance ​

  • Name capabilities, data ownership, contracts, deployment independence, and operational load for each boundary.
  • Write the smallest useful design note: purpose, inputs, outputs, state, failure behavior, observability, and rollback.
  • Choose the first implementation that can be tested against the real workflow without hiding a known production risk.

Tradeoffs ​

  • A modular monolith keeps coordination cheap; microservices isolate change at the cost of distributed failure.
  • Centralization reduces duplicated work but can become a bottleneck when every team needs exceptions.
  • Specialized infrastructure helps at scale, but it must earn its operational cost.

Failure Modes ​

  • A service boundary splits one transaction into fragile network choreography.
  • The diagram shows boxes but not ownership, retry behavior, data freshness, or user-visible failure.
  • The system has no proof path for the highest-risk assumption.

Decision Checklist ​

  • Write the reason for every process boundary and the data each service owns.
  • Name the owner, source of truth, timeout, retry policy, and evidence that the path works.
  • Add one regression check for the failure mode most likely to recur.

Neutral Automation Examples ​

  • A billing capability stays one module until traffic and ownership require an independently deployed service.
  • A neutral internal automation starts with fixtures, then adds credentials, permissions, and production scheduling only after the boundary is tested.
  • A customer-facing workflow keeps irreversible actions behind explicit approval until metrics show it is safe to automate further.