Browse all OPC Tags|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

I’m writing a simple OPC Client tool that downloads all OPC Tag / Variables with Qualified name, Data Type, Address, Array dimensions, Descriptions, Client Access Level. Below is my code snippet, it takes a while to load all tags, wondering we have any optimized way to query all tags at once. 

public async Task<List> GetAllVariableDefs()
{
List tags = new List();

string[] attr = new string[]
{
“_Address”,
“_Description”,
“_ScalingType”,
“_RawDataType”,
“_ClientAccess”,
};

var ret = BrowseAllVariables();
foreach (var item in ret)
{
try
{
NodeId localId = ExpandedNodeId.ToNodeId(item.NodeId, Session.NamespaceUris);
OPCRawTag rawTag = new OPCRawTag(localId.Identifier.ToString());
var ret2 = BrowseAllVariables(localId);
foreach (var item2 in ret2)
{
var vf = ((VariableNode)item2);
if (attr.ToList().Contains(item2.DisplayName.Text))
{
localId = ExpandedNodeId.ToNodeId(item2.NodeId, Session.NamespaceUris);
var n3 = Session.ReadValue(localId);
rawTag.Values.Add(item2.DisplayName.Text, n3.Value?.ToString());
}
}

tags.Add(new OPCTag(rawTag));
}
catch(Exception ex)
{

}
}
return tags;
}

private IList BrowseAllVariables(NodeId nodeId=null)
{
var result = new List();
var nodesToBrowse = new ExpandedNodeIdCollection {
nodeId == null ? ObjectIds.ObjectsFolder : nodeId
};

while (nodesToBrowse.Count > 0)
{
var nextNodesToBrowse = new ExpandedNodeIdCollection();
foreach (var node in nodesToBrowse)
{
try
{
var organizers = Session.NodeCache.FindReferences(
node,
ReferenceTypeIds.Organizes,
false,
true);
var components = Session.NodeCache.FindReferences(
node,
ReferenceTypeIds.HasComponent,
false,
true);
var properties = Session.NodeCache.FindReferences(
node,
ReferenceTypeIds.HasProperty,
false,
true);
nextNodesToBrowse.AddRange(organizers
.Where(n => n is ObjectNode)
.Select(n => n.NodeId).ToList());
nextNodesToBrowse.AddRange(components
.Where(n => n is ObjectNode)
.Select(n => n.NodeId).ToList());
result.AddRange(organizers.Where(n => n is VariableNode));
result.AddRange(components.Where(n => n is VariableNode));
result.AddRange(properties.Where(n => n is VariableNode));
}
catch (ServiceResultException sre)
{
if (sre.StatusCode == StatusCodes.BadUserAccessDenied)
{
Console.WriteLine($”Access denied: Skip node {node}.”);
}
}
}
nodesToBrowse = nextNodesToBrowse;
}
return result;
}

public class OPCTag
{
public string TagName { get; set; }
public string Address { get; set; }
public string DataType { get; set; }
public string ClientAccess { get; set; }
public string Description { get; set; }
public string ScalingType { get; set; }

public OPCTag()
{

}
public OPCTag(string name)
{
TagName = name;
}
public OPCTag(OPCRawTag rawTag)
{
TagName = rawTag.Name;
Address = rawTag.Values.ContainsKey(“_Address”) ? rawTag.Values[“_Address”] : string.Empty;
Description = rawTag.Values.ContainsKey(“_Description”) ? rawTag.Values[“_Description”] : string.Empty;
ScalingType = rawTag.Values.ContainsKey(“_ScalingType”) ? rawTag.Values[“_ScalingType”] : string.Empty;
ClientAccess = rawTag.Values.ContainsKey(“_ClientAccess”) ? rawTag.Values[“_ClientAccess”] : string.Empty;
DataType = rawTag.Values.ContainsKey(“_RawDataType”) ? rawTag.Values[“_RawDataType”] : string.Empty;
}
}

public class OPCRawTag
{
public string Name { get; set; }
public Dictionary<string,string> Values { get; set; }
public OPCRawTag(string name=””)
{
Name = name;
Values = new Dictionary<string, string>();
}
}