C# Signature:

[DllImport("wtsapi32.dll", SetLastError=true)]
static extern bool WTSEnumerateProcesses(
     IntPtr serverHandle,      // Handle to a terminal server.
     Int32  reserved,      // must be 0
     Int32  version,       // must be 1
     ref IntPtr ppProcessInfo, // pointer to array of WTS_PROCESS_INFO
     ref Int32  pCount);       // pointer to number of processes
);

VB Signature:

Private Declare Function WTSEnumerateProcesses Lib "wtsapi32.dll" ( _
     ByVal hServer As Int32, _
     ByVal Reserved As Int32, _
     ByVal Version As Int32, _
     ByRef ppProcessInfo As IntPtr, _
     ByRef pCount As Int32
) As Int32

User-Defined Types:

WTS_PROCESS_INFO

Alternative Managed API:

Much can be done with the System.Diagnostics.Process class with methods such as GetProcesses, GetProcessByName and GetProcessByID.

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

//C# sample code
public static WTS_PROCESS_INFO[] WTSEnumerateProcesses()
{
     IntPtr pProcessInfo = IntPtr.Zero;
     int processCount = 0;

     if (!WTSEnumerateProcesses(WTS_CURRENT_SERVER_HANDLE, 0, 1, ref pProcessInfo, ref processCount))
     return null;

     IntPtr pMemory = pProcessInfo;
     WTS_PROCESS_INFO[] processInfos = new WTS_PROCESS_INFO[processCount];
     for (int i = 0; i < processCount; i++)
     {
     processInfos[i] = (ProcessInfo)Marshal.PtrToStructure(pProcessInfo, typeof(WTS_PROCESS_INFO));
     pProcessInfo = (IntPtr)((int)pProcessInfo + Marshal.SizeOf(processInfos[i]));
     }

     WtsApi32.WTSFreeMemory(pMemory);
     return processInfos;
}

//VB sample code
    Dim strucProcessInfo As WTS_PROCESS_INFO
    Dim ptrProcessInfo As IntPtr
    Dim lngPtrPos As Long
    Dim intReturn As Integer
    Dim intCount As Integer
    Dim intProcessCount As Integer
    Dim strProcessName As String

    intReturn = WTSEnumerateProcesses(WTS_CURRENT_SERVER_HANDLE, 0, 1, ptrProcessInfo, intProcessCount)

    If intReturn > 0 Then
        'Get the length in bytes of each structure...
        lngPtrPos = ptrProcessInfo.ToInt32()

        For intCount = 0 To intProcessCount - 1
        strucProcessInfo = Marshal.PtrToStructure(New IntPtr(lngPtrPos), strucProcessInfo.GetType)
        'ProcessName is merely a pointer to the string - convert it to the full string...
        strProcessName = Marshal.PtrToStringAnsi(New IntPtr(strucProcessInfo.ProcessName))

        Console.WriteLine ("Process Name: " & strProcessName)
        Console.WriteLine ("Process ID: " & strucProcessInfo.ProcessID)
        Console.WriteLine ("Session ID: " & strucProcessInfo.SessionID)

        'Now move on the pointer to the next member of the array...
        lngPtrPos = lngPtrPos + Len(strucProcessInfo)
        Next
    End If

    Call WTSFreeMemory(ptrProcessInfo)