how to identify application instance name along with its user in vb.net 3.5? - vb.net

Question

I am using the below code to identify instance of the application also if we need to check that which user is using this application what will be the code for it?
Function PrevInstance() As Boolean
If Ubound(Diagnostics.Process.GetProcessesByName(Diagnostics.Process.GetCurrentProcess.ProcessName)) > 0 Then
Return True
Else
Return False
End If
End Function
My requirement is if same user tries to open the application then it should display pop up message like "application already opened".
Please advice...
abhay

Answer 1

Thanks a lot guys.... solution on my problem as follows:
> Function PrevInstance() As Boolean
> If UBound(Diagnostics.Process.GetProcessesByName(Diagnostics.Process.GetCurrentProcess.ProcessName))
> > 0 Then
> Dim CurUser As Boolean = GetProcessOwner(Diagnostics.Process.GetCurrentProcess.ProcessName)
> Return CurUser
> Else
> Return False
> End If
> End Function
Function GetProcessOwner(ByVal ProcessName As String) As Boolean
Dim boolVal As Boolean
Dim CurUserName As String
Dim CountInstance As Integer
CountInstance = 0
CurUserName = System.Environment.UserName
Dim selectQuery As SelectQuery = New SelectQuery("Select * from Win32_Process Where Name = '" + ProcessName + ".exe' ")
Dim searcher As ManagementObjectSearcher = New ManagementObjectSearcher(selectQuery)
Dim y As System.Management.ManagementObjectCollection
y = searcher.Get
For Each proc As ManagementObject In y
Dim s(1) As String
proc.InvokeMethod("GetOwner", CType(s, Object()))
Dim n As String = proc("Name").ToString()
If n = ProcessName & ".exe" Then
If s(0) = CurUserName Then
CountInstance = CountInstance + 1
If CountInstance > 1 Then
boolVal = True
End If
End If
End If
Next
Return boolVal
End Function
I have called PrevInstance() in my Form_Load() and its working perfectly.

Answer 2

PrevInstance Property
Returns a value indicating whether a previous instance of an application is already running.
Syntax
object.PrevInstance
The object placeholder represents an object expression that evaluates to an object in the Applies To list.
Remarks
You can use this property in a Load event procedure to specify whether a user is already running an instance of an application. Depending on the application, you might want only one instance running in the Microsoft Windows operating environment at a time.
Note Since a computer running Windows NT can support multiple desktops, if you use a component designed to work with distributed COM, it can result in the following scenario:
A client program in a user desktop requests one of the objects the component provides. Because the component is physically located on the same machine, the component is started in the user desktop.
Subsequently, a client program on another computer uses distributed COM to request one of the objects the component provides. A second instance of the component is started, in a system desktop.
There are now two instances of the component running on the same NT computer, in different desktops.
This scenario is not a problem unless the author of the component has placed a test for App.PrevInstance in the startup code for the component to prevent multiple copies of the component from running on the same computer. In this case, the remote component creation will fail.
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Session
The above tells you if it's already running. This tells you what session. An interactive user is always session1 on Vista and later. 0 for XP and earlier.
Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\cimv2")
Set colItems = objWMIService.ExecQuery("Select * From Win32_Process")
For Each objItem in colItems
msgbox objitem.name & " PID=" & objItem.ProcessID & " SessionID=" & objitem.sessionid
Next
PS
The rules for single instance programs is just before you exit you switch windows to the previous instance.
PPS
Due to problems introduced by 32 bit computing previnstance (Win32's one rather than VB's) becomes less meaningful. The common way to do this now is to open and lock a file on startup (Windows also has memory constructs you can use such as mailslots, pipes, etc). If a program can't lock then another is already running.