As we already knew we can install Access Database on a Local Area Network (LAN) and several Users can work on it at the same time. But it is difficult to know how many users are actually online with the Application at a given time.

Similarly, when there are several MS-Access Databases on a Network under a centrally controlled Security Workgroup it will be interesting to know which users are currently working on the MS-Access Applications on the Network.

You don’t need any complicated programs to find this out. When someone opens a Database, say NorthWind.mdb, MS-Access opens a Lock-File with the same name of the Database with file extension .ldb (Northwind.ldb) in the same folder of the Database. You can open this file with Notepad or any other Text Editor and view the contents.

This file contains the Workstation Ids and MS-Access User IDs of all the active Users of the Database. The lock file will be deleted by MS-Access when all the Users close the database. In other words if a Lock File is not active then nobody is currently using the database.

We can implement MS-Access Security of several Databases with a common Workgroup File in a Network holding Workgroup IDs, User IDs and User Passwords. In such situations there will be a common Workgroup File (a Database with .MDW extension) accessible to all the Users in a Network. When someone Log-in into the Workgroup to open a database, a lock-file with .ldb extension will open up with the same name of the Workgroup file. This file will contain the Workstation IDs and User IDs of all the Users currently active across different databases.

We will design a Form and write Programs to open the Lock-File of a Database or Workgroup File and display the List of Workstation IDs and User IDs currently active. In addition to that we will try to send messages through Network to the selected Users from this list.

  1. Design a Form similar to the one shown below and change the Properties of the Controls as explained. Smaller controls are Text Boxes and the big Control under the label Users Online is a List Box.

  2. Click on the Text Box below the label: Workgroup or Database File Path and display the property sheet. Change the value of the Name Property to FPath.
  3. Display the Property Sheet of the List Box and change the value of the following properties as given below:
    • Name = UsrList
    • Row Source Type = Value List
    • Column Count = 2
    • Column Heads = No
    • Column Width = 1.25";1.25"
    • Bound Column = 1
    • Multi Select = simple
  4. Display the property sheet of the Text Box above the Send Message Button and change the value of the Name Property to msgtxt.
  5. Display the Property Sheet of the Button with the caption < and change the value of the Name Property to cmdUpdate.
  6. Display the Property Sheet of the Button with the Caption Send Message and change the value of the Name property to cmdNS.
  7. Save the Form with the name; whoisonline.

    NB: We are referencing all the above Property Values in Programs and it is important that you change the Values of respective controls as explained above.

    Copy and Paste the following Code into the VB Module (Select Tools > Macro > Visual Basic Editor to display the VB Module) of the whoisonline Form, Save and Close the Form.


    Private Sub cmdNS_Click()
    'Author: a.p.r. pillai
    'Date  : 01/12/2007
    Dim ctl As ListBox, msg As String, usrs As String
    Dim i As Integer, pcs() As String, xmsg As String
    Dim ic As Integer, j As Integer, lc As Integer
    On Error GoTo cmdNS_Click_Err
    xmsg = Nz(Me.msgtxt, "")
    If Len(xmsg) = 0 Then
       MsgBox "Message Control is Empty.", , "cmdNS_Click()"
       Exit Sub
    End If
    Set ctl = Me.UsrList
    lc = ctl.listcount
    ic = ctl.ItemsSelected.Count
    If ic > 0 Then
    ReDim pcs(1 To ic, 1 To 2)
    i = 0
    For j = 0 To lc - 1
    If ctl.Selected(j) Then
        i = i + 1
        pcs(i, 1) = ctl.Column(0, j)
        pcs(i, 2) = ctl.Column(1, j)
    End If
    usrs = ""
    For j = 1 To i
    msg = "NET SEND " & pcs(j, 1) & " User: " & pcs(j, 2) & " " & xmsg
      Call Shell(msg)
      If Len(usrs) = 0 Then
         usrs = j & ". WorkStationID: " & pcs(j, 1) & "  UserID: " & pcs(j, 2)
         usrs = usrs & vbCr & j & ". WorkStationID: " & pcs(j, 1) & "  UserID: " & pcs(j,2)
      End If
      MsgBox "Messages Sent to:" & vbCr & vbCr & usrs & vbCr & vbCr & "successfully.", , "cmdNS_Click()"
      MsgBox "Select one or more Users in list and try again.", , "cmdNS_Click()"
    End If
    Exit Sub
    MsgBox Err.Description, , "cmdNS_Click()"
    Resume cmdNS_Click_Exit
    End Sub
    Private Sub cmdUpdate_Click()
        Me.cmdUpdate.Enabled = False
       WhoisOnline Me.FPath
        Me.cmdUpdate.Enabled = True
    End Sub

  8. Copy and Paste the following VB Code into a Global Module in your Project and save:

    Public Function WhoisOnline(ByVal strPathName)
    'Author : a.p.r. pillai
    'Date   : 01/12/2007
    Dim strldb() As String, j As Integer, strpath As String
    Dim str As String, intlen As Integer, t As Date
    Dim pos As Integer, xsize As Integer, l As Integer
    Dim FRM As Form, ctl As ListBox, qt As String
    Dim x As String
    Const strlen As Integer = 62
    On Error Resume Next
    qt = Chr$(34)
    strpath = Trim(Nz(strPathName, ""))
    If Len(strpath) = 0 Then
      MsgBox "File Path is Empty.", , "WhoisOnline()"
      Exit Function
    End If
    str = Right(strpath, 4)
    l = InStr(1, ".mdb.mdw.ldb", str)
    Select Case l
        Case 0
          strpath = strpath & ".ldb"
        Case 1, 5
          strpath = Left(strpath, Len(strpath) - 4) & ".ldb"
        Case 9       'it is .ldb no action
    End Select
    Set FRM = Forms("WhoisOnline")
    Set ctl = FRM.Controls("UsrList")
    Open "c:\x.bat" For Output As #1
    Print #1, "@Echo off"
    Print #1, "copy " & strpath & " c:\xx.txt"
    Close #1
    Call Shell("c:\x.bat", vbHide)
    x = Dir("c:\xx.txt")t = Timer
    Do While Len(x) = 0 And Timer < (t + 2)
       x = Dir("c:\xx.txt")
    t = Timer
    Do While Timer < (t + 2)   'do nothingLoop
    Open "c:\xx.txt" For Input As #1
    If Err > 0 Then
      'Lock file copying was not successfull
      MsgBox "Database is idle.", , "WhoisOnline()"
      Exit Function
    End If
    Input #1, str
    Close #1
    intlen = Int(Len(str) / strlen) + 1
    ReDim strldb(1 To intlen, 1 To 2) As String
    xsize = strlen / 2
    For j = 1 To intlen
      pos = IIf(j = 1, 1, (j - 1) * strlen + 1)
      strldb(j, 1) = Trim(Mid(str, pos, xsize))
      pos = pos + strlen / 2
      strldb(j, 2) = Trim(Mid(str, pos, xsize))
    str = ""
    For j = 1 To intlen
      If Len(str) = 0 Then
        str = qt & Trim(strldb(j, 1)) & qt & ";" & qt & Trim(strldb(j, 2)) & qt
        str = str & ";" & qt & Trim(strldb(j, 1)) & qt & ";" & qt & Trim(strldb(j, 2)) & qt
      End If
    ctl.RowSource = strctl.Requery
    Kill "c:\x.bat"
    Kill "c:\xx.txt"
    End Function

    In the above program we are creating a DOS Batch File (c:\x.bat) and running it, to make a copy of the Lock-File c:\xx.txt as a work file.

  9. Open the whoisonline Form in Normal View. Type the full path of an active database (Tip: give the Path and Name of the Database you are currently working on, if you are not on a Network). If you are on a Network and have a common MS-Access Workgroup File, which other Users are currently connected then give that File's Path and Name. No need to give File Name extensions .mdb, .mdw or .ldb, but if you wish to include you may do so for clarity.
  10. Click on the Button with < symbol.
  11. Select one or two Workstation IDs in the List Box.
  12. Type a Message in the Text Box Control above the Send Message Button for the selected Users.
  13. Click on the Send Message Button. The Message Text will pop up on the selected Users' Machines.

NB: If you have selected your own machine name then the Send Message action will not work.

Download Demo Database