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

<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