Question

Hey, I am trying to get a service to start my program but it isn’t showing the GUI. The process starts but nothing is shown. I have tried enabling ‘Allow service to interact with desktop’ but that still isn’t working.
My program is a computer locking device to stop unauthorised users from accessing the computer. I am running windows 7 with a 64 bit OS.

Here is the code for my service:

        protected override void OnStart(string[] args)
    {
        Process p = new Process();
        p.StartInfo.FileName = "notepad.exe";
        p.Start();

        FileStream fs = new FileStream(@"C:\Users\David\Documents\Visual Studio 2010\Projects\LockPCService\LockPCService\bin\Debug\ServiceLog.dj",
        FileMode.OpenOrCreate, FileAccess.Write);
        StreamWriter m_streamWriter = new StreamWriter(fs);
        m_streamWriter.BaseStream.Seek(0, SeekOrigin.End);
        m_streamWriter.WriteLine(" LockPCService: Service Started " + DateTime.Now + "\n" + "\n");
        m_streamWriter.Flush();
        m_streamWriter.Close();
    }

    protected override void OnStop()
    {
        FileStream fs = new FileStream(@"C:\Users\David\Documents\Visual Studio 2010\Projects\LockPCService\LockPCService\bin\Debug\ServiceLog.dj",
        FileMode.OpenOrCreate, FileAccess.Write);
        StreamWriter m_streamWriter = new StreamWriter(fs);
        m_streamWriter.BaseStream.Seek(0, SeekOrigin.End);
        m_streamWriter.WriteLine(" LockPCService: Service Stopped " + DateTime.Now + "\n"); m_streamWriter.Flush();
        m_streamWriter.Close();
    }

To try and get the service working I am using notepad.exe. When I look at the processes notepad is running but there is no GUI. Also the ServiceLog is there and working each time I run it.

Any ideas on why this isn’t working?

Thanks.

Answer 1

This article explains Session 0 Isolation which among other things disallows services from creating a UI in Windows Vista/7. In your service starts another process, it starts in Session 0 and also will not show any UI. (By the way, the UI is created, it’s just that Session 0 is never displayed). This article on CodeProject can help you create a process from a service on the user’s desktop and show its UI.

Also, please consider wrapping you stream objects in a using statement so that they are properly disposed.