cleanup tasks. There is no need to unregister the
agent, because when this method gets called it has
already been unregistered.
+
+ void ReportError(object service, string error)
+
+ This method gets called when an error has to be
+ reported to the user.
+
+ A special return value can be used to trigger a
+ retry of the failed transaction.
+
+ Possible Errors: [service].Error.Retry
+
+ string RequestPassphrase(object service)
+
+ This method gets called when trying to connect to
+ a service and a passphrase is missing.
+
+ The return value should be the passphrase string or
+ an error indicating that the request got cannceled.
+
+ Possible Errors: [service].Error.Canceled
+
+ void Cancel()
+
+ This method gets called to indicate that the agent
+ request failed before a reply was returned.