Returns true if a DicomAssociation is open, otherwise returns false. For outgoing connection, this property is true after the connection is 'opened' by Open method and before the connection is 'closed' by Close method. For incoming connection, if it is a C-GET request, the DicomAssociation object is passed as a property of the EventArguments.QueryReceivedArgs and the value is true. If it is a C-MOVE request, the value is false as the passed secondary connection has to be opened by the SCP to send requested images.