Opc.Ua.Sample.CustomNodeManager2.Read C# (CSharp) Method

        public virtual void Read(
            OperationContext     context, 
            double               maxAge, 
            IList<ReadValueId>   nodesToRead, 
            IList<DataValue>     values, 
            IList<ServiceResult> errors)
        {
            ServerSystemContext systemContext = m_systemContext.Copy(context);
            IDictionary<NodeId,NodeState> operationCache = new NodeIdDictionary<NodeState>();
            List<ReadWriteOperationState> nodesToValidate = new List<ReadWriteOperationState>();

            lock (Lock)
            {
                for (int ii = 0; ii < nodesToRead.Count; ii++)
                {                    
                    ReadValueId nodeToRead = nodesToRead[ii];

                    // skip items that have already been processed.
                    if (nodeToRead.Processed)
                    {
                        continue;
                    }
                    
                    // check for valid handle.
                    NodeState source = GetManagerHandle(systemContext, nodeToRead.NodeId, operationCache) as NodeState;

                    if (source == null)
                    {
                        continue;
                    }

                    // owned by this node manager.
                    nodeToRead.Processed = true;
                    
                    // create an initial value.
                    DataValue value = values[ii] = new DataValue();
                    
                    value.Value           = null;
                    value.ServerTimestamp = DateTime.UtcNow;
                    value.SourceTimestamp = DateTime.MinValue;
                    value.StatusCode      = StatusCodes.Good;

                    // check if the node is ready for reading.
                    if (source.ValidationRequired)
                    {
                        errors[ii] = StatusCodes.BadNodeIdUnknown;
                        
                        // must validate node in a seperate operation.
                        ReadWriteOperationState operation = new ReadWriteOperationState();
                        
                        operation.Source = source;
                        operation.Index = ii;

                        nodesToValidate.Add(operation);
                        
                        continue;
                    }

                    // read the attribute value.
                    errors[ii] = source.ReadAttribute(
                        systemContext,
                        nodeToRead.AttributeId,
                        nodeToRead.ParsedIndexRange,
                        nodeToRead.DataEncoding,
                        value);
                }

                // check for nothing to do.
                if (nodesToValidate.Count == 0)
                {
                    return;
                }

                // validates the nodes (reads values from the underlying data source if required).
                for (int ii = 0; ii < nodesToValidate.Count; ii++)
                {
                    ReadWriteOperationState operation = nodesToValidate[ii];

                    if (!ValidateNode(systemContext, operation.Source))
                    {
                        continue;
                    }
                    
                    ReadValueId nodeToRead = nodesToRead[operation.Index];
                    DataValue value = values[operation.Index];

                    // update the attribute value.
                    errors[operation.Index] = operation.Source.ReadAttribute(
                        systemContext,
                        nodeToRead.AttributeId,
                        nodeToRead.ParsedIndexRange,
                        nodeToRead.DataEncoding,
                        value);
                }
            }
        }