Signal Caching

Patriot is designed to detect and handle failure of any components while safely storing pending signal events.

Note: Here, 'Device' represents any system which reports signals into Patriot, e.g. an Alarm Receiver, IP Alarm Panel, DVR/Camera etc.

Normal Operation

While all components are available and working normally, signals flow through the system as follows:

• The Task Service receives events from devices, and sends any required acknowledgement.
• The Task Service sends the signal to the Data Service
• The Data Service saves the pending signal to the SQL Server database
• The Data Service processes any pending signals

Component Failure

Task Service Failure

If the Task Service is unavailable, devices will not be able to connect. In this case, the device must buffer signals until the Task Service is available.

Data Service Failure

If the Data Service is unavailable, all Task Services will continue to acknowledge signals from devices, and buffer the signals locally.

The Task Service will first cache signals to local RAM on the Task Server and then periodically - every ten seconds - save the RAM cache to the local storage directory^*

SQL Server

If SQL Server is unavailable, the Patriot Data Service will buffer any received signals locally.

The Data Service will cache the signals to local RAM on the Data Server and then periodically - every ten seconds - save the RAM cache to the local storage directory^*

^* Usually the local disk, but can be changed in the Task or Data Service configuration - see High Availability.

Offline Behaviour

It is possible to disable caching within the Task Service when either the Data Service or SQL Server is offline.

In this case, the Task Service does not send any required acknowledge to the device until the signal has been stored within SQL Server as a pending event.

See Task Settings - Offline Behaviour for more information.