Opc.Ua.Com.Server.ComDaBrowseCache.LookupChildElements C# (CSharp) Method

        private List<BrowseElement> LookupChildElements(Session session, BrowseElement parent)
        {
            List<BrowseElement> children = new List<BrowseElement>();
            List<BrowseElement> childrenToFind = new List<BrowseElement>();
            List<int> indexes = new List<int>();

            BrowseDescriptionCollection nodesToBrowse = new BrowseDescriptionCollection();

            // create an element for each child reference.
            foreach (ReferenceDescription reference in parent.ReferencesByName.Values)
            {
                NodeId nodeId = (NodeId)reference.NodeId;
                string itemId = m_mapper.GetLocalItemId(nodeId);

                BrowseElement child = null;

                lock (m_lock)
                {
                    // check if child has already been cached.
                    if (m_cache.TryGetValue(itemId, out child))
                    {
                        child.ParentId = parent.ItemId;
                        children.Add(child);
                        continue;
                    }

                    // create a new element.
                    child = new BrowseElement();
                }

                child.NodeId = nodeId;
                child.ItemId = itemId;
                child.NodeClass = reference.NodeClass;
                child.BrowseName = child.UaBrowseName = m_mapper.GetLocalBrowseName(reference.BrowseName);

                if (reference.DisplayName != null)
                {
                    child.BrowseName = reference.DisplayName.Text;
                }

                int index = PrepareBrowseElementBrowseRequest(child.NodeId, nodesToBrowse);

                childrenToFind.Add(child);
                indexes.Add(index);
            }

            // check if nothing to do because everything was in the cache.
            if (childrenToFind.Count == 0)
            {
                return children;
            }

            // browse all elements at once.
            BrowseResultCollection results = Browse(session, nodesToBrowse);

            // validate results and prepare read requests.
            ReadValueIdCollection nodesToRead = new ReadValueIdCollection();

            for (int ii = 0; ii < childrenToFind.Count; ii++)
            {
                BrowseElement child = childrenToFind[ii];

                // update the element with the children found.
                if (!UpdateBrowseElement(child, nodesToBrowse, results, indexes[ii]))
                {
                    children[ii] = null;
                    continue;
                }

                // all done with objects.
                if (child.NodeClass == NodeClass.Object)
                {
                    child.ParentId = parent.ItemId;
                    children.Add(child);

                    lock (m_lock)
                    {
                        child.CacheTimestamp = DateTime.UtcNow;
                        m_cache[child.ItemId] = child;
                    }
                }

                // prepare to read the properties from the server.
                indexes[ii] = PrepareBrowseElementReadRequest(child.NodeId, child.ReferencesByName, nodesToRead, child.NodeClass, true);
            }

            // check if nothing to do because only objects with no properties..
            if (nodesToRead.Count == 0)
            {
                return children;
            }

            // read all child properties at once.
            DataValueCollection values = Read(session, nodesToRead);

            // process results and build final table.
            for (int ii = 0; ii < childrenToFind.Count; ii++)
            {
                BrowseElement child = childrenToFind[ii];

                if (child == null || child.NodeClass == NodeClass.Object)
                {
                    continue;
                }

                // update the browse element with the property values.
                if (!UpdateBrowseElement(session.TypeTree, child, nodesToRead, values, child.NodeClass, true, indexes[ii]))
                {
                    continue;
                }

                // add variables to the cache.
                child.ParentId = parent.ItemId;
                children.Add(child);

                lock (m_lock)
                {
                    child.CacheTimestamp = DateTime.UtcNow;
                    m_cache[child.ItemId] = child;
                }
            }

            return children;
        }