// BrowseAndReadValues: Console application that recursively browses and displays the nodes in the OPC address space, and 
// attempts to read and display values of all OPC items it finds.
 
using System.Diagnostics;
using JetBrains.Annotations;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.DataAccess;
using System;
 
namespace BrowseAndReadValues
{
    class Program
    {
        const string ServerClass = "OPCLabs.KitServer.2";
 
        [NotNull]
        static readonly EasyDAClient Client = new EasyDAClient();
 
        static void BrowseAndReadFromNode([NotNull] string parentItemId)
        {
            // Obtain all node elements under parentItemId
            var nodeFilter = new DANodeFilter();    // no filtering whatsoever
            DANodeElementCollection nodeElementCollection = Client.BrowseNodes("", ServerClass, parentItemId, nodeFilter);
            // Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for it, here 
            // omitted for brevity.
 
            foreach (DANodeElement nodeElement in nodeElementCollection)
            {
                Debug.Assert(nodeElement != null);
 
                // If the node is a leaf, it might be possible to read from it
                if (nodeElement.IsLeaf)
                {
                    // Determine what the display - either the value read, or exception message in case of failure.
                    string display;
                    try
                    {
                        object value = Client.ReadItemValue("", ServerClass, nodeElement);
                        display = String.Format("{0}", value);
                    }
                    catch (OpcException exception)
                    {
                        display = String.Format("** {0} **", exception.GetBaseException().Message);
                    }
 
                    Console.WriteLine("{0} -> {1}", nodeElement.ItemId, display);
                }
                // If the node is not a leaf, just display its itemId
                else
                    Console.WriteLine("{0}", nodeElement.ItemId);
 
                // If the node is a branch, browse recursively into it.
                if (nodeElement.IsBranch &&
                    (nodeElement.ItemId != "SimulateEvents") /* this branch is too big for the purpose of this example */)
                    BrowseAndReadFromNode(nodeElement);
            }
        }
 
        static void Main()
        {
            Console.WriteLine("Browsing and reading values...");
            // Set timeout to only wait 1 second - default would be 1 minute to wait for good quality that may never come.
            Client.InstanceParameters.Timeouts.ReadItem = 1000;
 
            // Do the actual browsing and reading, starting from root of OPC address space (denoted by empty string for itemId)
            BrowseAndReadFromNode("");
 
            Console.WriteLine("Press Enter to continue...");
            Console.ReadLine();
        }
    }
}