Opc.Ua.Sample.SampleNodeManager.ModifyMonitoredItem C# (CSharp) Method

        protected virtual ServiceResult ModifyMonitoredItem(
            ISystemContext context,
            DiagnosticsMasks diagnosticsMasks,
            TimestampsToReturn timestampsToReturn,
            IMonitoredItem monitoredItem,
            MonitoredItemModifyRequest itemToModify,
            out MonitoringFilterResult filterError)
        {
            filterError = null;
            ServiceResult error = null;

            // check for valid handle.
            MonitoredNode monitoredNode = monitoredItem.ManagerHandle as MonitoredNode;

            if (monitoredNode == null)
            {
                return ServiceResult.Good;
            }

            if (IsHandleInNamespace(monitoredNode.Node) == null)
            {
                return ServiceResult.Good;
            }

            // owned by this node manager.
            itemToModify.Processed = true;

            // check for valid monitored item.
            DataChangeMonitoredItem datachangeItem = monitoredItem as DataChangeMonitoredItem;

            // validate parameters.
            MonitoringParameters parameters = itemToModify.RequestedParameters;

            // validate the data change filter.
            DataChangeFilter filter = null;
            Range range = null;

            if (!ExtensionObject.IsNull(parameters.Filter))
            {
                error = ValidateDataChangeFilter(
                    context,
                    monitoredNode.Node,
                    datachangeItem.AttributeId,
                    parameters.Filter,
                    out filter,
                    out range);

                if (ServiceResult.IsBad(error))
                {
                    return error;
                }
            }

            double previousSamplingInterval = datachangeItem.SamplingInterval;
            
            // check if the variable needs to be sampled.
            double samplingInterval = itemToModify.RequestedParameters.SamplingInterval;

            if (datachangeItem.AttributeId == Attributes.Value)
            {
                BaseVariableState variable = monitoredNode.Node as BaseVariableState;

                if (variable.MinimumSamplingInterval > 0)
                {
                    samplingInterval = CalculateSamplingInterval(variable, samplingInterval);
                }
            }

            // modify the monitored item parameters.
            error = datachangeItem.Modify(
                diagnosticsMasks,
                timestampsToReturn,
                itemToModify.RequestedParameters.ClientHandle,
                samplingInterval,
                itemToModify.RequestedParameters.QueueSize,
                itemToModify.RequestedParameters.DiscardOldest,
                filter,
                range);

            // do any post processing.
            OnModifyMonitoredItem(
                context, 
                itemToModify, 
                monitoredNode, 
                datachangeItem,
                previousSamplingInterval);

            return ServiceResult.Good;
        }