How to read input and write output on telnet window of command line?

Question

I want to receive input from command line when my device scans barocode and give barcode related information to the conmmand line on telnet window which we start from login in telnet server through cmd.exe by "telnet 192.168.x.x 23" and after typing this command in cmd then login succsessfull telnet window opens and and my machin connected to device , now I have to read barcode string from this window and display output related to that string. please give me any idea how to do this?

here is my code which simply manually enter input string and after pressing enter gives output.

namespace ConsoleApplication2
{
    class Program
    {
    private static System.Timers.Timer aTimer;
    string path = @"C:\Users\Priya\Desktop\Project\barcode.txt";

    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["SaiNathHospital"].ToString());

    public void getConsoleInput()
    {
        try
        {
            FileInfo fi = new FileInfo(path);

            for (int i = 0; i <= 0; i++)
            {
                Console.WriteLine("");
                using (StreamWriter sw = new StreamWriter(path))
                {
                    sw.WriteLine(Console.ReadLine());
                    sw.Close();
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }

    public void getConsoleInputAtRuntime()
    {

    }

    public void ReadWriteIntoFile()
    {
        try
        {
            string filename = @"C:\Users\Priya\Desktop\Project\Data.txt";
            StringBuilder sb = new StringBuilder();

            StreamReader sr = new StreamReader(path);
            string s = sr.ReadLine();
            sr.Close();

            DataExport("Select * from PATIENT_TABLE where [BARCODE] = '" + s + "'", filename);
        }
        catch { }
    }

    public void DataExport(string SelectQuery, string filename)
    {
        try
        {
            using (var dt = new DataTable())
            {
                using (var da = new SqlDataAdapter(SelectQuery, con))
                {
                    da.Fill(dt);
                    var rows =
                        from dr in dt.Rows.Cast<DataRow>()
                        select String.Join(
                            ",",
                            from dc in dt.Columns.Cast<DataColumn>()
                            let t1 = Convert.IsDBNull(dr[dc]) ? "" : dr[dc].ToString()
                            let t2 = t1.Contains(",") ? String.Format("\"{0}\"", t1) : t1
                            select t2);

                    using (var sw = new StreamWriter(filename))
                    {
                        // sw.WriteLine(header);
                        foreach (var row in rows)
                        {
                            sw.WriteLine(row);
                        }
                        sw.Close();
                    }
                }
            }
        }
        catch (Exception e) { Console.WriteLine(e.Message); }
    }

    public void WriteFileOutput()
    {
        string path = @"C:\Users\Priya\Desktop\Project\Data.txt";
        if (File.Exists(path))
        {
            string[] lines = File.ReadAllLines(path);

            foreach (string line in lines)
            {
                Console.WriteLine(line);
            }
        }
        Console.ReadLine();
    }

    public void  timer()
        {
            aTimer = new System.Timers.Timer();

            aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
            aTimer.Interval = 10000;
            aTimer.Enabled = true;

            Console.WriteLine("Press the Enter key to exit the program.\n");
            Console.ReadLine();
        }

    private static void OnTimedEvent(object source, ElapsedEventArgs e)
        {
            //System.Windows.Forms.SendKeys.Send("{ENTER}");
            Console.WriteLine("5 seconds Elapsed at {0} ", e.SignalTime); // for your reference to check every five seconds
        }

    public static void Main(string[] args)
    {             
      Program p = new Program();     
      p.getConsoleInput();
      p.ReadWriteIntoFile();
      p.WriteFileOutput();
    }   
}

}

Answer 1

Priyanka, welcome to SO. The approach I would take towards this would be to programatically issue the telnet and wait for the response from the telnet. Now since, you are logging in the ConsoleApplication2 is not aware of the session.

So, here is the high level approach towards the solution

1. Launch your ConsoleApplication2 application
2. Use a Telnet library to open the connection towards the device
3. Read the response of scan from the Telnet using the same library
4. Do the database thing with the response.

The problem will become simpler if you have a Telnet library. However, there is a similar question in SO and a library which was recommended here - Executing commands by using Telnet in C#

Hope this helps!