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

        protected ServiceResult ValidateDataChangeFilter(
            ISystemContext context,
            NodeState source,
            uint attributeId,
            ExtensionObject requestedFilter,
            out DataChangeFilter filter,
            out Range range)
        {
            filter = null;
            range = null;

            // check for valid filter type.
            filter = requestedFilter.Body as DataChangeFilter;

            if (filter == null)
            {
                return StatusCodes.BadMonitoredItemFilterUnsupported;
            }

            // only supported for value attributes.
            if (attributeId != Attributes.Value)
            {
                return StatusCodes.BadMonitoredItemFilterUnsupported;
            }

            // only supported for variables.
            BaseVariableState variable = source as BaseVariableState;
            
            if (variable == null)
            {
                return StatusCodes.BadMonitoredItemFilterUnsupported;
            }

            // check the datatype.
            if (filter.DeadbandType != (uint)DeadbandType.None)
            {
                BuiltInType builtInType = TypeInfo.GetBuiltInType(variable.DataType, Server.TypeTree);

                if (!TypeInfo.IsNumericType(builtInType))
                {
                    return StatusCodes.BadMonitoredItemFilterUnsupported;
                }
            }
            
            // validate filter.
            ServiceResult error = filter.Validate();

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

            if (filter.DeadbandType ==(uint)DeadbandType.Percent)
            {
                BaseVariableState euRange = variable.FindChild(context, BrowseNames.EURange) as BaseVariableState;

                if (euRange == null)
                {
                    return StatusCodes.BadMonitoredItemFilterUnsupported;
                }

                range = euRange.Value as Range;
                
                if (range == null)
                {
                    return StatusCodes.BadMonitoredItemFilterUnsupported;
                }
            }

            // all good.
            return ServiceResult.Good;
        }