Windows System Time Synchronizer

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Introduction

This is a simple utility written in C# .NET Version 2.0. It synchronizes Windows system time with Yahoo! server time through a web service offered by Yahoo!.

Using the code

The utility makes an HTTP request to the Yahoo! URL, which returns Yahoo! server time as a timestamp in XML format. Then the XML is parsed to get the timestamp and is converted into regional date-time. Windows system time is modified to this using a P-Invoke function call.

/*
 * WINDOWS TIME SYNCHRONIZER - C# .NET
 * 
 * FILE NAME    :    Program.cs
 * 
 * DATE CREATED :    March 06, 2007, 12:05:54 PM
 * CREATED BY   :    Gunasekaran Paramesh
 * 
 * LAST UPDATED :    April 25, 2007, 12:38:12 PM
 * UPDATED BY   :    Gunasekaran Paramesh
 * 
 * DESCRIPTION  :    Synchronizes Windows System Time with Yahoo! Server Time.
*/

using System;
using System.Net;
using System.Xml;
using System.IO;
using System.Threading;
using System.Diagnostics;
using Microsoft.Win32;
using System.Configuration;
using System.Runtime.InteropServices;

namespace TryWinTimeSync
{
    class Program
    {
        [StructLayout(LayoutKind.Sequential)]
        public struct SYSTEMTIME 
        {
            public short wYear;
            public short wMonth;
            public short wDayOfWeek;
            public short wDay;
            public short wHour;
            public short wMinute;
            public short wSecond;
            public short wMilliseconds;
        }

        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern bool SetSystemTime( [In] ref SYSTEMTIME st );

        [STAThread]
        static void Main(string[] args)
        {
            BooleanSwitch Tracer = new BooleanSwitch("TraceSwitch", 
                "Trace for entire application");
            EventLog Log = null;

            try
            {
                // Initialize EventLog
                Log = new EventLog();
                if(!System.Diagnostics.EventLog.SourceExists("WinTimeSync"))
                    System.Diagnostics.EventLog.CreateEventSource(
                        "WinTimeSync", "Zion");
                Log.Source = "WinTimeSync";
                Log.Log = "Zion";
                
                if ( Tracer.Enabled )
                    Trace.Listeners.Add(new EventLogTraceListener(Log));

                Trace.WriteLineIf(Tracer.Enabled, "Starting WinTimeSync...");

                Boolean ServiceAlive = true;
                Double CurrentTimestamp = 0;

                Trace.WriteLineIf(Tracer.Enabled, 
                    "Opening configuration file for initializing" + 
                    " global settings...");

                Int32 SyncInterval = Convert.ToInt32(
                    ConfigurationSettings.AppSettings[
                    "SyncInterval"].ToString());
                String RequestURL = ConfigurationSettings.AppSettings[
                    "TimeServerURL"].ToString();

                Trace.WriteLineIf(Tracer.Enabled, 
                    "Global settings initialized [SyncInterval: " + 
                    SyncInterval + " minutes; RequestURL: " + 
                    RequestURL + "]");

                while ( ServiceAlive )
                {
                    Trace.WriteLineIf(!Tracer.Enabled, 
                    "Synchronizing system time with time server...");

                    // Send HTTP request for Timestamp
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Creating HTTP request to [" + RequestURL + "]");
                    WebRequest Req = WebRequest.Create(RequestURL);
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Setting default proxy for the HTTP request...");
                    Req.Proxy = WebProxy.GetDefaultProxy();
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Sending HTTP request...");
                    WebResponse Res = Req.GetResponse();

                    // Save as Timestamp as a temporary XML file
                    String TempFile = Guid.NewGuid().ToString() + ".xml";
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Creating a temporary XML file [" + TempFile + "]");
                    StreamWriter SW = new StreamWriter(TempFile);
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Saving HTTP response to the temporary XML file...");
                    SW.Write(new StreamReader(
                        Res.GetResponseStream()).ReadToEnd());
                    SW.Close();

                    // Read the XML file and get the Timestamp value
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Opening the temporary XML file...");
                    XmlTextReader MyXML = new XmlTextReader(TempFile);
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Reading the temporary XML file...");
                    while ( MyXML.Read() )
                    {
                        switch ( MyXML.NodeType )
                        {
                            case XmlNodeType.Element:
                            if ( MyXML.Name == "Timestamp" )
                            {
                                Trace.WriteLineIf(Tracer.Enabled, 
                                    "Retriving the current timestamp" + 
                                    " from the temporary XML file...");
                                CurrentTimestamp = Convert.ToDouble(
                                    MyXML.ReadInnerXml());
                                Trace.WriteLineIf(Tracer.Enabled, 
                                    "Current timestamp retrived [
                                    " + CurrentTimestamp + "]");
                            }
                            break;
                        }
                    }
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Closing the temporary XML file...");
                    MyXML.Close();

                    // Delete the temporary XML file
                    FileInfo TFile = new FileInfo(TempFile);
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Deleting the temporary XML file...");
                    TFile.Delete();

                    // Convert Timestamp to Time
                    DateTime MyDateTime = 
                        new DateTime(1970, 1, 1, 0, 0, 0, 0);
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Converting the timestamp to time...");
                    MyDateTime = MyDateTime.AddSeconds(CurrentTimestamp);
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Timestamp converted to time [
                        " + MyDateTime.ToLocalTime() + "]");

                    // Change the system time
                    SYSTEMTIME SysTime = new SYSTEMTIME();
                    SysTime.wYear = (short) MyDateTime.Year;
                    SysTime.wMonth = (short) MyDateTime.Month; 
                    SysTime.wDay = (short) MyDateTime.Day;
                    SysTime.wHour = (short) MyDateTime.Hour;
                    SysTime.wMinute = (short) MyDateTime.Minute;
                    SysTime.wSecond = (short) MyDateTime.Second;
                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Setting the system time...");
                    SetSystemTime(ref SysTime);

                    Trace.WriteLineIf(Tracer.Enabled, 
                        "Switching to sleep state until SyncInterval...");
                    for ( int i = 0; i < SyncInterval; i++ )
                        Thread.Sleep(1000 * 60);
                        Trace.WriteLineIf(Tracer.Enabled, 
                            "Switching back to active mode...");
                }
            }
            catch ( Exception Ex )
            {
                // Log for errors                
                if ( Tracer.Enabled )
                    Log.WriteEntry(Ex.StackTrace, EventLogEntryType.Error);
                else
                    Log.WriteEntry(Ex.Message, EventLogEntryType.Error);
            }
        }
    }
}

Sample configuration file

Below is the sample configuration file. TraceSwitch is used to enable debug log messages. SyncInterval specifies the elapsed time in seconds where the utility synchronizes the Windows system time with the Yahoo! time server. TimeServerURL specifies the actual Yahoo! URL which, on request, returns the server time.

<configuration>
    <system.diagnostics>
        <switches>
            <add name="TraceSwitch" value="1" />
        </switches>
    </system.diagnostics>
    <appSettings>
        <add key="SyncInterval" value="60" />
        <add key="TimeServerURL" value=
"http://developer.yahooapis.com/TimeService/V1/getTime?appid=YahooDemo" />
    </appSettings>
</configuration>

History

• Baseline v1.0 - April 25, 2007