Usage in DataSource source applications

An ISubjectStatusEvent can be raised by an IDataProvider to indicate to peers the status of their subscription to a subject. For example, if the back end system that feeds data to an IDataProvider goes down, the IDataProvider should raise a ISubjectStatusEvent with a Status of Stale to indicate to the peer that the data it has is not completely up-to-date. When an update is subsequently received from the backend data feed, then the IDataProvider should raise a ISubjectStatusEvent with a Status of Ok to indicate to the peer that the data it has is now up to date.