Used by a Requestor to begin a subscription, to be notified of changes to a property's value.

Used by a Requestor to begin a subscription, as specified using a Control , to be notified of changes to a property's value.

NOTE: The Property's current value is always returned when the subscription is started.

NOTE: Intermediate changes that occur more frequently than minPeriod may be dropped to save bandwidth, but the most current value of the Property is always returned.

NOTE: Interest is required (through DOFSystem.beginInterest(DOFObjectID, DOFInterestLevel) for this operation in order to determine the primary provider. If no interest is specified, then this operation will result in a DOFErrorException.TIMEOUT exception.

NOTE: If the primary provider changes during the lifetime of this operation, and the Control response level includes exceptions, then see SubscribeOperationListener.propertyChanged(Subscribe, DOFProviderInfo, DOFValue, DOFException) for what to do.