Service provider states
A single companion service can provide multiple services. Each service has a state that is stored in the AR System Service Failover Whiteboard form.
State transitions
Service provider states
| State | Description |
|---|---|
Active | The service provider is processing requests. |
Suspending | The service provider has been told to complete or abort any in-progress request and relinquish ownership of the service. |
Waiting | The service provider is available to process requests. |
Unavailable | The heartbeat from the service provider is no longer being detected. (As part of a graceful shutdown, the service provider can assert that it is no longer available.) |
Within a server group, one node has an active service failover controller, which drives state transition for the group. If the AR System server with that node goes down, another node in the server group receives ownership of the controller. For more information about the controller, see Service Failover Ranking Entries.
Service provider state transitions
| Original state | New state | Changes driven by the AR System server | Changes driven by the service provider |
|---|---|---|---|
| Active | Unavailable | The AR System server did not detect a heartbeat, which indicates that the service provider is not working or is unavailable to take ownership of a service. | The service provider has shut down and is no longer available. |
| Waiting | Unavailable | The AR System server did not detect a heartbeat, which indicates that the service provider is no longer available to take ownership of a service. | The service provider has shut down and is no longer available. |
| Suspending | Unavailable | The AR System server did not detect a heartbeat, which indicates that the service provider is still gracefully suspending work in progress. | The service provider gracefully completes all the in-progress requests and then is no longer available. |
| Active | Suspending | The AR System server intends to fail over the service from one service provider to another. The AR System server gives the active service provider the ability to gracefully finish any work that is currently under way. | Not applicable. The service provider cannot assert a suspending state. |
| Active | Waiting | Not applicable. Only the service provider can assert a waiting state. | The service provider has completed its requests and intends to give the AR System platform the opportunity to recalculate the highest ranked service provider for the service. The AR System server would detect that there is no active service provider for the service, examine the ranking criteria and available service providers, and give ownership to (that is, make active) the appropriate service provider. |
| Waiting | Active | The AR System server intends to fail over the service from one service provider to another. The AR System server indicates to a waiting service provider that it should take ownership of the service and begin processing. | Not applicable. Only the AR System server can determine and assign ownership of the service. |
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