Each service
What every microservice owns.
Each service has a single responsibility, its own Postgres
schema, and the patterns that responsibility forces. Stack,
patterns, and a click-driven demo for the headline pattern.
Single gateway from the browser to every microservice. Rate-limit, circuit-break, idempotency-replay, and the chaos fault-injection handler all live here.
ASP.NET Core 9 Polly v8 SignalR YARP-style proxy
Patterns this service owns
Rate limit (token bucket)
Sliding-window token bucket per session. Replies 429 + Retry-After when the bucket empties; refills steadily.
Circuit breaker
Polly StandardResilienceHandler wraps every outbound HttpClient. Opens after consecutive failures, half-opens on probe success.
Drive it · headline pattern
JWT issuance, refresh, JTI revocation, and dynamic Postgres credentials sourced from Vault.
ASP.NET Core 9 EF Core HashiCorp Vault OpenIddict-style JTI
Patterns this service owns
Vault dynamic credentials
Postgres connection strings rotate every hour via Vault leases. The connection interceptor swaps the active credential without dropping in-flight queries.
Drive it · headline pattern
Products, stock, OCC. Two replicas via Aspire WithReplicas. The hot path for every browse, every checkout.
ASP.NET Core 9 EF Core Postgres xmin HybridCache (Redis L2)
Patterns this service owns
Optimistic concurrency (xmin)
Postgres `xmin` shadow column is the EF concurrency token. Concurrent updates → exactly one wins, the rest get 412.
Cache invalidation
L1 in-process + L2 Redis. Invalidations propagate via a Redis pub/sub channel so all replicas converge.
Drive it · headline pattern
Idempotent claim creation. Owns the public idempotency contract for the storefront.
ASP.NET Core 9 EF Core Postgres ON CONFLICT
Patterns this service owns
Idempotency via ON CONFLICT
`INSERT … ON CONFLICT (key) DO UPDATE … RETURNING claim_id, (xmax = 0)` makes the first writer win and every replay return the same claim id without a transaction.
Drive it · headline pattern
Stripe + PayPal webhook processors. Transactional outbox for outbound MassTransit events.
ASP.NET Core 9 EF Core MassTransit Stripe.NET PayPalClient
Patterns this service owns
Transactional outbox
Webhook handler writes the payment row + an OutboxMessage in one transaction. A background worker dispatches the event to RabbitMQ; if dispatch fails the next pass retries.
Drive it · headline pattern
The saga state machine. Coordinates StockReservation → PaymentSession → Capture → Complete, with a compensation arc on every step.
ASP.NET Core 9 MassTransit Saga State Machine EF Core (saga persistence)
Patterns this service owns
Place-order saga
State machine driven by published events. Every state transition is persisted; every failure path has a named compensating event. Visualised below.
Drive it · headline pattern