// This example shows how to obtain data types of leaves in the OPC-DA address 
// space by browsing and filtering, i.e. without the use of OPC properties. 
// This technique allows determining the data types with servers that only 
// support OPC-DA 1.0. It can also be more effective than the use of 
// GetMultiplePropertyValues, if there is large number of leaves, and 
// relatively small number of data types to be checked.
 
using System;
using System.Collections.Generic;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.DataAccess;
 
namespace DocExamples
{
    namespace _EasyDAClient
    {
        /*partial*/ class BrowseNodes
        {
            public static void DataTypes()
            {
                var easyDAClient = new EasyDAClient();
 
                // Define the list of data types we will be checking for. 
                // Change as needed for your application.
                // This technique is only usable if there is a known list of 
                // data types you are interested in. If you are interested in 
                // all leaves, even those that are of data types not explicitly 
                // listed, always include VarType.Empty as the first data type. 
                // The leaves of "unlisted" data types will have VarType.Empty 
                // associated with them.
                var dataTypes = new VarType[] { VarType.Empty, VarType.I2, VarType.R4 };
 
                // For each leaf found, this dictionary wil hold its associated data type.
                var dataTypeDictionary = new Dictionary<DANodeElement, VarType>();
 
                // For each data type, browse for leaves of this data type.
                foreach (VarType dataType in dataTypes)
                {
                    var nodeFilter = new DANodeFilter(DABrowseFilter.Leaves, "", "", dataType);
                    DANodeElementCollection nodeElements =
                        easyDAClient.BrowseNodes("", "OPCLabs.KitServer.2", "Greenhouse", nodeFilter);
 
                    // Store the leaf information into the dictionary, and 
                    // associate the current data type with it.
                    foreach (var nodeElement in nodeElements)
                        dataTypeDictionary[nodeElement] = dataType;
                }
 
                // Display each leaf found, and its associated data type.
                foreach (KeyValuePair<DANodeElement, VarType> pair in dataTypeDictionary)
                {
                    DANodeElement nodeElement = pair.Key;
                    VarType dataType = pair.Value;
                    Console.WriteLine("{0}: {1}", nodeElement, dataType);
                }
            }
        }
    }
}

// This example shows how to obtain a data type of all OPC items under a branch.
 
using System;
using System.Linq;
using OpcLabs.BaseLib;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.DataAccess;
 
namespace DocExamples
{
    namespace _EasyDAClient
    {
        class GetMultiplePropertyValues
        {
            public static void DataType()
            {
                var easyDAClient = new EasyDAClient();
                ServerDescriptor serverDescriptor = "OPCLabs.KitServer.2";
 
                // Browse for all leaves under the "Simulation" branch
                DANodeElementCollection nodeElementCollection = easyDAClient.BrowseLeaves(serverDescriptor, "Simulation");
 
                // Create list of property descriptors for the DataType property, one for each leaf obtained
                DAPropertyDescriptor[] propertyDescriptorArray = nodeElementCollection
                    .Where(element => !element.IsHint)  // filter out hint leafs that do not represent real OPC items (rare)
                    .Select(element => new DAPropertyDescriptor(element, DAPropertyId.DataType))
                    .ToArray();
 
                // Get the value of DataType property; it is a 16-bit signed integer
                ValueResult[] valueResultArray = easyDAClient.GetMultiplePropertyValues(serverDescriptor, 
                    propertyDescriptorArray);
 
                for (int i = 0; i < valueResultArray.Length; i++)
                {
                    DAPropertyDescriptor propertyDescriptor = propertyDescriptorArray[i];
 
                    // Check if there has been an error getting the property value
                    ValueResult valueResult = valueResultArray[i];
                    if (valueResult.Exception != null)
                    {
                        Console.WriteLine("{0}: *** {1}", propertyDescriptor.ItemId, valueResult.Exception.Message);
                        continue;
                    }
 
                    // Convert the data type to VarType
                    var varType = (VarType)(short)valueResult.Value;
 
                    // Display the obtained data type
                    Console.WriteLine("{0}: {1}", propertyDescriptor.ItemId, varType);
                }
            }
        }
    }
}