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writing a service in VB.NET

I have an existing c++ (actually, g++) program that registers as a service - and then - while running - reacts to the presence of a text file. Depending on the content of the lines in the text file - the service will do one of two things:

1) start a new process - running a batch file created by the internet user via an ASP page.

--Or--
2) send a small TCP/IP packet to a UNIX machine which has a companion daemon listening for the imcoming packet.

I'm trying to port this existing code to VB.NET.

The two winapi functions that the existing service uses are these:

if (LogonUser((LPTSTR)UserName, (LPTSTR)Domain, (LPTSTR)Passwd, 

LOGON32_LOGON_SERVICE, LOGON32_PROVIDER_DEFAULT, &hUserHandle)) {

--and--

if (CreateProcessAsUser(hUserHandle, NULL, (CHAR*)line.c_str(),

 NULL, NULL, FALSE, (DWORD)NULL, NULL, NULL, &si, &pi)) {

The problem is - I cannot get the second function to work in VB.NET - I've tried just about every variation on this system call - searched the web for examples - and haven't found anything that will get this last function to work.

Here's one example of the VB function declaration and the call that I've tried. To no avail.

Public Declare Auto Function CreateProcessAsUser Lib "advapi32.dll" ( _

    ByVal hToken As IntPtr, _

    ByVal strApplicationName As String, _

    ByVal strCommandLine As String, _

    ByRef lpProcessAttributes As SECURITY_ATTRIBUTES, _

    ByRef lpThreadAttributes As SECURITY_ATTRIBUTES, _

    ByVal bInheritHandles As Boolean, _

    ByVal dwCreationFlags As Integer, _

    ByVal lpEnvironment As IntPtr, _

    ByVal lpCurrentDriectory As String, _

    ByRef lpStartupInfo As STARTUPINFO, _

    ByRef lpProcessInformation As PROCESS_INFORMATION) As Boolean



Public Structure SECURITY_ATTRIBUTES

    Public nLength As Integer

    Public lpSecurityDescriptor As IntPtr

    Public bInheritHandle As Boolean

End Structure



Public Structure PROCESS_INFORMATION

    Public hProcess As IntPtr

    Public hThread As IntPtr

    Public dwProcessId As Integer

    Public dwThreadId As Integer

End Structure



Public Structure STARTUPINFO

    Public cb As Integer

    Public lpReserved As IntPtr

    Public lpDesktop As IntPtr

    Public lpTitle As IntPtr

    Public dwX As Integer

    Public dwY As Integer

    Public dwXSize As Integer

    Public dwYSize As Integer

    Public dwXCountChars As Integer

    Public dwYCountChars As Integer

    Public dwFillAttribute As Integer

    Public dwFlags As Integer

    Public wShowWindow As Short

    Public cbReserved2 As Short

    Public lpReserved2 As IntPtr

    Public hStdInput As IntPtr

    Public hStdOutput As IntPtr

    Public hStdError As IntPtr

End Structure

Then - in the sub main...

Dim saProc As SECURITY_ATTRIBUTES = New SECURITY_ATTRIBUTES

Dim saThread As SECURITY_ATTRIBUTES = New SECURITY_ATTRIBUTES

saProc.nLength = Marshal.SizeOf(saProc)

saProc.lpSecurityDescriptor = IntPtr.Zero

saThread.nLength = Marshal.SizeOf(saThread)

saThread.lpSecurityDescriptor = IntPtr.Zero

If CreateProcessAsUser( _

    hToken, _

    String.Empty, _

    strCmdLine, _

    saProc, _

    saThread, _

    False, _

    0, _

    IntPtr.Zero, _

    String.Empty, _

    si, _

    pi) Then

(We're still using vb.net from VS 2003 - so the new 'process class' that came out with the 2.0 framework isn't available to me for this project. :-( )