When the SIF Agent starts up, it immediately attempts to connect to all zones that are not in a disabled state. (You can temporarily disable connectivity with a zone via the Zone Settings dialog box.) Connecting to a zone involves sending several registrations and provisioning messages:
- SIF_Request is sent to update the server with the current registration settings
- SIF_Subscribe is sent for each object the agent is currently subscribing to
- SIF_Provide is sent for each object the agent is currently providing
- A request for SIF_ZoneStatus is optionally sent to obtain zone status information
Any messages that are pending in the agent's queue will be received and processed as soon as the agent connects to the zone.
When the agent is shut down it places itself in Sleep Mode in each zone so the server will not try and contact it.
SIF is a reliable messaging system. Any messages delivered to the agent when it is not running will be safely queued on the zone integration server. This may result in an interruption of services to other agents in the zone (e.g. if the agent is a Provider of one or more object types, other applications in the zone will not be able to request objects from it), but there is no risk of data loss.