Get Windows Uptime using C# and WMI

Sometime ago I use to compare my OS uptime with some friends; it was like an Uptime Competition (We had a lot of free time ;-)). I don't know why but today I remembered it and I thought about if I could obtain my OS Uptime using C#. About one year ago or so I worked a bit with WMI when I was coding against the Windows Media Server API, and since then I think that WMI is a good way to obtain information about our system.

I've checked the WMI reference at MSND and I got a WMI class that has the last time boot up date. The class that hosts this date is Win32_OperatingSystem among other data; such Windows install date and other interesting things. Once we have that the only thing we can do is... to Code !!

The method shown below obtains the last boot up time from the property LastBootUpTime of the Win32_OperatingSystem class, so I created ManagementClass object to get the instances of the WMI class. Then I looped thought it elements to obtain the date, it's easy.

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--> 1 /// 
 2 /// Obtains the OS uptime
 3 /// 
 4 /// TimeSpan object that contains the uptime
 5 public TimeSpan GetUptime()
 6 {
 7     //timespan object to store the result value
 8     TimeSpan uptimeTs = new TimeSpan();
 9 
10     //management objects to interact with WMI
11     ManagementClass management = new ManagementClass("Win32_OperatingSystem");
12     ManagementObjectCollection mngInstance = management.GetInstances();
13 
14     //loop throught the mngInstance
15     foreach (ManagementObject mngObject in mngInstance)
16     {
17         //get the LastBootUpTime date parsed
18         DateTime lastBootUp = ParseCIMDateTime(mngObject["LastBootUpTime"].ToString());
19 
20         //check it value is not DateTime.MinValue
21         if (lastBootUp != DateTime.MinValue)
22         {
23             //get the diff between dates
24             uptimeTs = DateTime.Now - lastBootUp;
25         }
26     }
27 
28     //return the uptime TimeSpan
29     return uptimeTs;
30 }

The DateTime format that WMI works with is the CIM_DATETIME. The dates are represented as strings with a specific format. This format is covered in depth at WMI reference at MSDN. But the date format isn't a problem, it's a human readable format. The string 20070112204559.115081+060 represents 12/01/2007 20:45:59,115, so I created a method to parse CIM dates to .Net DateTime objects.

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--> 1 /// 
 2 /// Parses a CIM_DateTime string
 3 /// 
 4 /// 
 5 /// The CIM_DateTime format is represented by the following string: 
 6 /// yyyy MM dd hh mm ss.mmm mmm UTC
 7 /// 2007 01 12 20 45 59.115 081+060
 8 /// 
 9 /// Input CIM_DateTime string
10 /// DatTime object that represents the CIM_DateTIme input string
11 private static DateTime ParseCIMDateTime(string wmiDate)
12 {
13     //datetime object to store the return value
14     DateTime date = DateTime.MinValue;
15     
16     //check date integrity
17     if (wmiDate != null && wmiDate.IndexOf('.') != -1)
18     {
19         //obtain the date with miliseconds
20         string tempDate = wmiDate.Substring(0, wmiDate.IndexOf('.') + 4);
21 
22         //check the lenght
23         if (tempDate.Length == 18)
24         {
25             //extract each date component
26             int year = Convert.ToInt32(tempDate.Substring(0, 4));
27             int month = Convert.ToInt32(tempDate.Substring(4, 2));
28             int day = Convert.ToInt32(tempDate.Substring(6, 2));
29             int hour = Convert.ToInt32(tempDate.Substring(8, 2));
30             int minute = Convert.ToInt32(tempDate.Substring(10, 2));
31             int second = Convert.ToInt32(tempDate.Substring(12, 2));
32             int milisecond = Convert.ToInt32(tempDate.Substring(15, 3));
33 
34             //compose the new datetime object
35             date = new DateTime(year, month, day, hour, minute, second, milisecond);        
36         }
37     }
38 
39     //return datetime
40     return date;
41 }

This is all the logic that we need to obtain our OS uptime. I wrote a small console application that outputs the OS uptime in the format:

"Uptime: 7 days, 2 hours, 2 minutes, 7 seconds and 317 milliseconds"

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--> 1 /// <summary>
 2 /// Console entry point
 3 /// </summary>
 4 private static void Main()
 5 {
 6     //create an instace of the UpTime class
 7     Uptime uptime = new Uptime();
 8 
 9     //obtain the TimeSpan that represents the uptime
10     TimeSpan ts = uptime.GetUptime();
11 
12     //write the uptime to the output
13     Console.WriteLine(String.Format("Uptime: {0} days, {1} hours, {2} minutes, {3} seconds and {4} miliseconds",
14                                     ts.Days, ts.Hours, ts.Minutes, ts.Seconds, ts.Milliseconds));
15 }

WMI Reference at MSDN: http://msdn2.microsoft.com/en-us/library/aa394582....
Win32_OperatingSystem Class reference: http://msdn2.microsoft.com/en-us/library/aa394239....
CIM_DateTime format reference: http://msdn2.microsoft.com/en-us/library/aa387237....

That's all folks!! I hope you like it