Opc.Ua.Com.Server.ComDaGroup.SyncRead C# (CSharp) Method

        public DaValue[] SyncRead(uint maxAge, int[] serverHandles, bool isInitialRefresh, int[] clientHandles)
        {
            TraceState("SyncRead", maxAge, serverHandles.Length);
            ThrowIfDisposed();

            DaValue[] results = new DaValue[serverHandles.Length];
            List<ComDaGroupItem> items = new List<ComDaGroupItem>(serverHandles.Length);
            ReadValueIdCollection valuesToRead = new ReadValueIdCollection();

            lock (m_lock)
            {
                // validate items.
                for (int ii = 0; ii < serverHandles.Length; ii++)
                {
                    results[ii] = new DaValue();

                    ComDaGroupItem item = null;

                    if (!m_itemsByHandle.TryGetValue(serverHandles[ii], out item))
                    {
                        results[ii].Error = ResultIds.E_INVALIDHANDLE;
                        continue;
                    }

                    if (clientHandles != null)
                    {
                        clientHandles[ii] = item.ClientHandle;
                    }

                    // check for cache read.
                    if (maxAge == UInt32.MaxValue)
                    {
                        // inactive items cannot be read from cache.
                        if (!item.Active || !m_active)
                        {
                            results[ii].Quality = OpcRcw.Da.Qualities.OPC_QUALITY_OUT_OF_SERVICE;
                            results[ii].Timestamp = DateTime.UtcNow;
                            continue;
                        }
                      
                        // check if waiting for initial data.
                        if (item.CacheEntry == null)
                        {
                            results[ii].Quality = OpcRcw.Da.Qualities.OPC_QUALITY_WAITING_FOR_INITIAL_DATA;
                            results[ii].Timestamp = DateTime.UtcNow;
                            continue;
                        }

                        // get the latest value from the cache.
                        item.CacheEntry.GetLatest(results[ii]);
                        UpdateReadResult(item, results[ii]);
                        continue;
                    }

                    // apply max age.
                    if (maxAge > 0)
                    {
                        if (item.CacheEntry != null)
                        {
                            if (item.CacheEntry.CacheTimestamp.AddMilliseconds(maxAge) > DateTime.UtcNow)
                            {
                                item.CacheEntry.GetLatest(results[ii]);
                                UpdateReadResult(item, results[ii]);
                                continue;
                            }
                        }
                    }

                    // schedule read from device.
                    ReadValueId valueToRead = new ReadValueId();

                    valueToRead.NodeId = item.NodeId;
                    valueToRead.AttributeId = Attributes.Value;
                    valueToRead.Handle = ii;

                    valuesToRead.Add(valueToRead);
                    items.Add(item);
                }
            }

            if (valuesToRead.Count  == 0)
            {
                return results;
            }

            // read the values from the server.
            DaValue[] remoteResults = m_manager.Read(valuesToRead);
            
            // copy results.
            for (int ii = 0; ii < valuesToRead.Count; ii++)
            {
                int index = (int)valuesToRead[ii].Handle;

                if (isInitialRefresh)
                {
                    UpdateCache(items[ii], remoteResults[ii], isInitialRefresh);
                }

                UpdateReadResult(items[ii], remoteResults[ii]);
                results[(int)valuesToRead[ii].Handle] = remoteResults[ii];
            }

            return results;
        }