Figure 9.3. Cache Management

The on-premise HGA acts as a security panel by caching credential information from the access control system. This allows the device to interact with the elevator system even when communications fails between the HGA and the access control system. In addition, it ensures fast, low-latency interactions between itself and the elevator controller(s).

Credentials from the access control system are automatically refreshed in both "fast" and "full" modes. In "fast" mode, the HGA uses the capabilties of the access control system API to acquire recently changed user and credential information. This is usually either instantenous, or within a minute or two contingent upon the ACS's API capabilities. In "full" mode, the HGA performs a full synchronization of all cardholder information from the access control system. Since this is a time and compute-intenstive process, this is typically scheduled for execution once per night.

Administrators and Deployers can view the state of the cache -- how many records have been synchronized by the access control system as well as when the last record(s) have been synchronized by tapping the Cache tab of the Access Systems panel. If no synchronization has yet occurred, ??? is displayed for both values. By tapping the Sync Fast button, the HGA will execute a "fast" synchronization and update the cache information accordingly.

	Note
	If no records have been recently modified in the access control system, the Last Sync attribute will not be updated.

By clicking the Sync Full button, the HGA will execute a "full" synchronization, ensuring that the HGA's internal cache matches the full population of cardholders in the access system.