Connecting to a Redundant Historian

The OpenConnection() method of class MultiHistorianAccess is similar to the one of HistorianAccess, but it also activates the partner historian discovery mechanism, which in turn can create additional internal instances of the HistorianAccess class if a partner historian is found.

The OpenConnection() method sets the ErrorOccurred property of the multi-historian connection status to true only if all partner historians have an error condition. In other words, if at least one partner historian is available, the system is not considered to be in an error condition.

The OpenConnectionToAll() method sets the ErrorOccurred property of the multi-historian connection status to true if at least one partner historian has an error condition. Use this function when it is mandatory for your application to have both partner historians available at the moment of opening a connection. 

Example

MultiHistorianAccess multiHistorian = new MultiHistorianAccess();
HistorianConnectionArgs connectionArgs = new HistorianConnectionArgs();
connectionArgs.ServerName = "HistorianServerA";
connectionArgs.UserName   = "MyDomain\\MyUserName";
connectionArgs.Password   = "MyPassword";

HistorianAccessError error;
if (!multiHistorian.OpenConnection(connectionArgs, out error))
    Console.WriteLine("Failed to initiate multi-historian connection: {0}",
        error.Description);