VB.net: Getting the list of files open in an application

How can I get, using VB.net,  a list of all files open in an application for example Excel or Autocad?
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Saqib Husain, SyedEngineerAsked:
Who is Participating?
Try the following for Excel.  I'm not familiar with Autocad, but it should be similar.

Dim excel As Object
Dim wb As Object

	excel = System.Runtime.InteropServices.Marshal.GetActiveObject ( "Excel.Application" )

	For Each wb In excel.Workbooks
		Console.WriteLine ( wb.FullName )

	excel = Nothing
	Console.WriteLine("Excel is not open.")
End Try

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are you trying to get a list of files open over the network or files opened on the current workstation?
Saqib Husain, SyedEngineerAuthor Commented:
Current workstation
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Saqib Husain, SyedEngineerAuthor Commented:
I need code to do this as I am new to VB.net
It turns out listing used files is not as simple as it seems.  It requires calls to low level Windows API's that unless the code is running as a driver will very likely hang.  More details about this issue on the links below:

The solution below relies on a small but powerfull Sysinternal utlity called Handle by Mark Russinovich.  This utility displays information about open handles for any process in the system.

The sample code below executes Handle and captures its output, which is then parsed to retrieve the list of open files.

Before trying the sample, download Handle from the link below, include handle.exe (400KB) to your VS project, and set it to 'Copy to Output Directory = Copy if newer'.

Imports System.IO

Module Module1

    Sub Main()
        Dim pr As Process

        For Each pr In Process.GetProcessesByName("excel")
            Dim file As String

            For Each file In GetFilesOpenedByProcess(pr)

    End Sub

    Private Function GetFilesOpenedByProcess(ByVal theProcess As Process) As List(Of String)
        Dim cmd As New Process()
        Dim cmdInfo As ProcessStartInfo = New ProcessStartInfo("handle", "-p " & theProcess.Id.ToString())
        Dim files As List(Of String) = New List(Of String)

        cmdInfo.UseShellExecute = False
        cmdInfo.RedirectStandardOutput = True

        cmd.StartInfo = cmdInfo

        Dim rdr As StreamReader = cmd.StandardOutput
        Dim output As String = rdr.ReadToEnd()


        Dim lines() As String = output.Split(vbCr)
        Dim line As String

        For Each line In lines
            If line.Length > 22 Then
                If line.Substring(8, 4) = "File" Then
                End If
            End If

        Return files
    End Function

End Module

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This code works on my Windows XP machine, but I have not tried it on other OS versions yet.

I hope this helps.
Saqib Husain, SyedEngineerAuthor Commented:
I really do not have any intention to go into APIs and handles.

I had been accessing autocad documents from excel and excel documents from autocad using methods like

set acd=getobject(,"Autocad.application")
for each dwg in acd.documents
next dwg

and I was hoping to do the same in vb.net with appropriate syntax. (The above did not work)

For AutoCAD, here is some sample code from the AutoCAD .NET Developer's Guide, found here:

Imports System
Imports System.Runtime.InteropServices
Imports Autodesk.AutoCAD.Interop
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
<CommandMethod("ConnectToAcad")> _
Public Sub ConnectToAcad()
  Dim acAppComObj As AcadApplication
  Dim strProgId As String = "AutoCAD.Application.18"
  On Error Resume Next
  '' Get a running instance of AutoCAD
  acAppComObj = GetObject(, strProgId)
  '' An error occurs if no instance is running
  If Err.Number > 0 Then
      '' Create a new instance of AutoCAD
      acAppComObj = CreateObject("AutoCAD.Application.18")
      '' Check to see if an instance of AutoCAD was created
      If Err.Number > 0 Then
         '' If an instance of AutoCAD is not created then message and exit
         MsgBox("Instance of 'AutoCAD.Application' could not be created.")
         Exit Sub
      End If
  End If
  '' Display the application and return the name and version
  acAppComObj.Visible = True
  MsgBox("Now running " & acAppComObj.Name & " version " & acAppComObj.Version)
  '' Get the active document
  Dim acDocComObj As AcadDocument
  acDocComObj = acAppComObj.ActiveDocument
  '' Optionally, load your assembly and start your command or if your assembly
  '' is demandloaded, simply start the command of your in-process assembly.
  acDocComObj.SendCommand("(command " & Chr(34) & "NETLOAD" & Chr(34) & " " & _
                          Chr(34) & "c:/myapps/mycommands.dll" & Chr(34) & ") ")
  acDocComObj.SendCommand("MyCommand ")
End Sub

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