# Architecture and terminology

Keystone Gateway sits between product installations and a vendor-issued Gateway license. The Gateway is authoritative for live lease allocation; the signed license is authoritative for which deployment and capacities it may serve.

flowchart LR
  L\[Signed Gateway license\] --\> G\[Customer-operated Gateway\]
  P\[PHOCOL / LMC Exporter installation\] --\>|acquire, renew, release| G
  G --\>|time-bounded capacity grant| P

-   **Gateway**: customer-operated licensing hub.
-   **Node**: a product installation requesting authority to run. In client code this is represented by a persistent **instance identity**.
-   **Gateway node identity**: configured `gateway_id` plus replica ID, checked against the signed license.
-   **Entitlement**: licensed concurrent capacity for a component; “seat” is not a separate V1 object.
-   **Licensed component**: independently requested component under `phocol` or `lmc_exporter`.
-   **Principal**: an authenticated caller identity. Each principal is authorized for exactly one product license type; deployments serving both types use separate principals.
-   **Lease**: time-bounded allocation to one product installation. A client may continue only until its last successful lease expires.
-   **Standalone**: one Gateway replica with no redundancy.
-   **Active/Standby**: the V1 two-replica topology; one writes normally, the other can become degraded-active after peer loss.
-   **Stable endpoint**: client-reachable DNS names or an optional readiness-aware VIP; clients should have both replica targets.
-   **Offline reporting**: local report generation and customer-controlled transfer; no runtime vendor connection.