Glossary

Audience: all readersStatus: reference

Terms as they are used in these docs.

Term	Meaning here
Service	An independently deployed application owning one business domain and its own database (employees, customers, …). See Platform and services.
Core	The canonical, vendor-agnostic data model inside a service. Source of truth.
Vendor app	The quarantined mirror of one external system, living inside a service.
Anti-corruption layer	The design rule that vendor shapes must never leak into core. The vendor app is the layer.
Mirror	Our stored copy of a vendor record, keyed on the vendor's own identifier.
Upsert	Insert-or-update: applying a mirrored record to the canonical model.
Outbox	The pattern that makes provisioning survive crashes — the core row and the job that creates its vendor record commit together. Field changes reach vendors through the scheduled sync instead.
Idempotent	Doing it twice has the same effect as doing it once. Required in both directions — see Errors and retries.
Convergence key	A normalized field used to land records from two different external systems on the same canonical row.
Client credentials	OAuth2 grant for machine-to-machine auth: client_id + client_secret exchanged for a short-lived access token. No user involved. See Authentication.
Bounded context	The reach of one consistent vocabulary; our services are drawn on these lines. See Domain modelling.
Field authority	Which side wins when a field exists on both sides. A business decision, settled per field in discovery.
Hub, not bus	esz-backend routes between systems; a connected system never receives data whose only purpose is forwarding to a third.
esz product	A core ESZ service — calibration, training, CEPS — as opposed to other services such as battery change or device cleaning.
Manufacturer model	The manufacturer's model an esz product is applied to.
Device	A manufacturer model plus a serial number: one physical instrument.