microservices

# Microservices (Deep Workflow) Microservices trade **code simplicity** for **operational and contract complexity**. Justify each boundary with **ownership** and **data isolation**—not fashion. ## When to Offer This Workflow **Trigger conditions:** - Splitting the monolith; coupling blocks independent deploys - Latency cascades, partial failures, contract breaks - Conway’s law alignment between teams and services **Initial offer:** Use **six stages**: (1) goals & constraints, (2) boundaries & data ownership, (3) integration patterns, (4) contracts & versioning, (5) reliability patterns, (6) ops & governance). Confirm org maturity and platform capabilities. --- ## Stage 1: Goals & Constraints **Goal:** Why not a modular monolith first? ### Valid drivers - Independent deploy cadence per team - Different scaling profiles or stacks - Clear domain ownership and blast-radius isolation ### Costs - Distributed transactions, harder debugging, broader test matrix **Exit condition:** Explicit assumption that modular monolith was considered. --- ## Stage 2: Boundaries & Data Ownership **Goal:** One service owns each aggregate’s write path; no shared writable tables across services. ### Practices - Bounded contexts from DDD when helpful **Exit condition:** Entity → owning service map. --- ## Stage 3: Integration Patterns **Goal:** Sync HTTP/gRPC vs async events—match consistency needs. ### Patterns - Sagas or outbox for multi-step business processes **Exit condition:** Sequence diagrams for top three flows. --- ## Stage 4: Contracts & Versioning **Goal:** Backward-compatible evolution; consumer-driven contracts optional. ### Practices - Deprecation policy published --- ## Stage 5: Reliability Patterns **Goal:** Timeouts, retries with backoff, circuit breakers, bulkheads; idempotent handlers for retries. --- ## Stage 6: Ops & Governance **Goal:** Service catalog, SLIs on dependency edges, golden paths for new services. --- ## Final Review Checklist - [ ] Boundary and data ownership clear - [ ] Integration style matches consistency needs - [ ] Contract versioning policy exists - [ ] Reliability patterns applied at boundaries - [ ] Ops ownership and catalog in place ## Tips for Effective Guidance - Microservices without delivery maturity often fail—say so explicitly. - Shared databases are hidden coupling—flag them. - The network is not reliable—design for partial failure. ## Handling Deviations - Small teams: strong bias toward modular monolith or few services.