How I made an OPC2WEB client using Google

/*=====================================================================
  File:      OPCCSharp.cs

  Summary:   OPC sample client for C#

-----------------------------------------------------------------------
  This file is part of the Viscom OPC Code Samples.

  Copyright(c) 2001 Viscom (www.viscomvisual.com) All rights reserved.

THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
PARTICULAR PURPOSE.
======================================================================*/

using System;
using System.Threading;
using System.Runtime.InteropServices;
using System.Configuration;
using OPC.Common;
using OPC.Data;
using System.Net;
using System.Globalization;
using System.Data.SqlClient;
using System.Data;
using System.Net.Sockets;


namespace CSSample
{
    class Tester
    {
        // ***********************************************************	EDIT THIS :
        string serverProgID = ConfigurationManager.AppSettings["opcID"];         // ProgID of OPC server

        private OpcServer theSrv;
        private OpcGroup theGrp;
        private static float[] currentValues;
        private static string responseStringG ="";
        private static HttpListener listener = new HttpListener();

        private static string consoleOut = ConfigurationManager.AppSettings["consoleOutput"];
        private static string answerType = ConfigurationManager.AppSettings["answerType"];
        private static string portNumb = ConfigurationManager.AppSettings["portNumber"];
        private static int timeref = Int32.Parse(ConfigurationManager.AppSettings["refreshTime"]);
        private static string[] tagsNames = ConfigurationManager.AppSettings["tagsNames"].Split(','); // tags from config
        private static string[] ratios = ConfigurationManager.AppSettings["ratios"].Split(',');

        private static string sqlSend = ConfigurationManager.AppSettings["sqlSend"];
        private static string udpSend = ConfigurationManager.AppSettings["udpSend"];
        private static string webSend = ConfigurationManager.AppSettings["webSend"];
        private static string table_name = ConfigurationManager.AppSettings["table"]; //    ;
        private static string column_name = ConfigurationManager.AppSettings["column"];
        private static int sendtags = Int32.Parse(ConfigurationManager.AppSettings["tags2send"]);
        
        private static IPAddress remoteIPAddress = IPAddress.Parse(ConfigurationManager.AppSettings["remoteIP"]); // Ip from config
        private static int remotePort = Convert.ToInt16(ConfigurationManager.AppSettings["remotePort"]); // remote port from config

        public static SqlConnection myConn = new SqlConnection(ConfigurationManager.ConnectionStrings["connstr"].ConnectionString); //   SQL    
        SqlCommand myCommand = new SqlCommand("Command String", myConn);

        public void Work()
        {
            /*	try						// disabled for debugging
                {	*/

            theSrv = new OpcServer();
            theSrv.Connect(serverProgID);
            Thread.Sleep(500);              // we are faster then some servers!

            // add our only working group
            theGrp = theSrv.AddGroup("OPCCSharp-Group", false, timeref);

            string[] tags = ConfigurationManager.AppSettings["tags"].Split(','); // tags from config
            if (sendtags > tags.Length) sendtags = tags.Length;

                var itemDefs = new OPCItemDef[tags.Length];
            for (var i = 0; i < tags.Length; i++)
            {
                itemDefs[i] = new OPCItemDef(tags[i], true, i, VarEnum.VT_EMPTY);
            }

            OPCItemResult[] rItm;
            theGrp.AddItems(itemDefs, out rItm);
            if (rItm == null)
                return;
            if (HRESULTS.Failed(rItm[0].Error) || HRESULTS.Failed(rItm[1].Error))
            {
                Console.WriteLine("OPC Tester: AddItems - some failed"); theGrp.Remove(true); theSrv.Disconnect(); return;

            };

            var handlesSrv = new int[itemDefs.Length];
            for (var i = 0; i < itemDefs.Length; i++)
            {
                handlesSrv[i] = rItm[i].HandleServer;
            }

            currentValues = new Single[itemDefs.Length];

            // asynch read our two items
            theGrp.SetEnable(true);
            theGrp.Active = true;
            theGrp.DataChanged += new DataChangeEventHandler(this.theGrp_DataChange);
            theGrp.ReadCompleted += new ReadCompleteEventHandler(this.theGrp_ReadComplete);


            int CancelID;

            int[] aE;
            theGrp.Read(handlesSrv, 55667788, out CancelID, out aE);

            // some delay for asynch read-complete callback (simplification)
            Thread.Sleep(500);

            while (webSend=="yes")
            {
                HttpListenerContext context = listener.GetContext();
                HttpListenerRequest request = context.Request;
                HttpListenerResponse response = context.Response;
                context.Response.AddHeader("Access-Control-Allow-Origin", "*");


                byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseStringG);
                // Get a response stream and write the response to it.
                response.ContentLength64 = buffer.Length;
                System.IO.Stream output = response.OutputStream;
                output.Write(buffer, 0, buffer.Length);
                // You must close the output stream.
                output.Close();
            }
            // disconnect and close
            Console.WriteLine("************************************** hit <return> to close...");
            Console.ReadLine();
            theGrp.ReadCompleted -= new ReadCompleteEventHandler(this.theGrp_ReadComplete);
            theGrp.RemoveItems(handlesSrv, out aE);
            theGrp.Remove(false);
            theSrv.Disconnect();
            theGrp = null;
            theSrv = null;


            /*	}
            catch( Exception e )
                {
                Console.WriteLine( "EXCEPTION : OPC Tester " + e.ToString() );
                return;
                }	*/
        }

        // ------------------------------ events -----------------------------

        public void theGrp_DataChange(object sender, DataChangeEventArgs e)
        {

            foreach (OPCItemState s in e.sts)
            {
                if (HRESULTS.Succeeded(s.Error))
                {
                    if (consoleOut == "yes")
                    {
                        Console.WriteLine(" ih={0} v={1} q={2} t={3}", s.HandleClient, s.DataValue, s.Quality, s.TimeStamp); //      
                    }
                    currentValues[s.HandleClient] = Convert.ToSingle(s.DataValue) * Single.Parse(ratios[s.HandleClient], CultureInfo.InvariantCulture.NumberFormat); //     
                }
                else
                    Console.WriteLine(" ih={0}    ERROR=0x{1:x} !", s.HandleClient, s.Error);
            }
            string responseString = "{";
            if (answerType == "table")
            {
                responseString = "<HTML><head><meta charset=\"UTF-8\"><meta http-equiv=\"Refresh\" content=\"" + timeref / 1000 + "\"/></head>" +
            "<BODY><table border><tr><td>" + string.Join("<br>", tagsNames) + "</td><td >" + string.Join("<br>", currentValues) + "</td></tr></table></BODY></HTML>";
                responseStringG = responseString;
            }
            else
            {
                for (int i = 0; i < currentValues.Length - 1; i++) responseString = responseString + "\"tag" + i + "\":\"" + currentValues[i] + "\", ";
                responseString = responseString + "\"tag" + (currentValues.Length - 1) + "\":\"" + currentValues[currentValues.Length - 1] + "\"}";
                responseStringG = responseString;
            }
            byte[] byteArray = new byte[sendtags * 4];
            Buffer.BlockCopy(currentValues, 0, byteArray, 0, byteArray.Length);
            if (sqlSend == "yes")
            {
                try
                {
                    SqlCommand cmd = new SqlCommand("INSERT INTO " + table_name + " (" + column_name + ") values (@bindata)", myConn);
                    myConn.Open();
                    var param = new SqlParameter("@bindata", SqlDbType.Binary)
                    { Value = byteArray };
                    cmd.Parameters.Add(param);
                    cmd.ExecuteNonQuery();
                    myConn.Close();
                }
                catch (Exception err)
                {
                    Console.WriteLine("SQL-exception: " + err.ToString());
                    return;
                }
            }

            if (udpSend == "yes")  UDPsend(byteArray);
        }

        private static void UDPsend(byte[] datagram)
        {
            //  UdpClient
            UdpClient sender = new UdpClient();

            //  endPoint     
            IPEndPoint endPoint = new IPEndPoint(remoteIPAddress, remotePort);

            try
            {

                sender.Send(datagram, datagram.Length, endPoint);
                //Console.WriteLine("Sended", datagram);
            }
            catch (Exception ex)
            {
                Console.WriteLine(" : " + ex.ToString() + "\n  " + ex.Message);
            }
            finally
            {
                //  
                sender.Close();
            }
        }
        public void theGrp_ReadComplete(object sender, ReadCompleteEventArgs e)
        {
            Console.WriteLine("ReadComplete event: gh={0} id={1} me={2} mq={3}", e.groupHandleClient, e.transactionID, e.masterError, e.masterQuality);
            foreach (OPCItemState s in e.sts)
            {
                if (HRESULTS.Succeeded(s.Error))
                {
                    Console.WriteLine(" ih={0} v={1} q={2} t={3}", s.HandleClient, s.DataValue, s.Quality, s.TimeStamp);
                }
                else
                    Console.WriteLine(" ih={0}    ERROR=0x{1:x} !", s.HandleClient, s.Error);
            }
        }

        static void Main(string[] args)
        {
            string url = "http://*";
            string port = portNumb;
            string prefix = String.Format("{0}:{1}/", url, port);
            listener.Prefixes.Add(prefix);
            listener.Start();
            
            Tester tst = new Tester();
            tst.Work();
        }
    }
}

/* add this code to app.exe.config file
<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
  </startup>
  <appSettings>
    <add key="opcID" value="Graybox.Simulator" />
    <add key="tagsNames" value="Line Speed,Any name, " />
    <add key="tags" value="numeric.sin.int16,numeric.sin.int16,numeric.sin.int16" />
    <!-- ratios for tags -->
    <add key="ratios" value="1,0.5,0.1" />
    <add key="portNumber" value="45455" />
    <add key="refreshTime" value="1000" />
    <!-- "yes" or no to show values in console-->
    <add key="consoleOutput" value="yes" />
    <add key="webSend" value="no" /> 
    <!-- "table" or json (actually any other word for json)-->
    <add key="answerType" value="json" />

    <add key="sqlSend" value="no" />
    <add key="table" value="raw_tbl" />
    <add key="column" value="data" />
    
    <add key="udpSend" value="yes" />
    <add key="remotePort" value="3310"/>
    <add key="remoteIP" value="127.0.0.1"/>

    <add key="tags2send" value="2" />
    
  </appSettings>
  
  <connectionStrings>
    <add connectionString="Password=12345;Persist Security Info=True;User ID=user12345;Initial Catalog=amt;Data Source=W7-VS2017" name="connstr" />
  </connectionStrings>
   
</configuration>
     */