Windows System Time Synchronizer

/*
 * 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);
			}
		}
	}
}