Prevent opening second instance of excel?

[Herry Markowitz]

Hi there,
My question is regarding VBA and vb.net.

I found following VBA codes from this source http://www.mrexcel.com/forum/excel-q...lications.html
Following codes prevents opening second instance of excel.
Let me tell you how following code works.
If someone try to open second excel file then following code close second excel file immediately.

Public WithEvents myApp As Application
Private Sub myApp_WorkbookOpen(ByVal Wb As Workbook)
    Wb.Close
End Sub

Public aApp As Class1

Sub Test()
    Set aApp = New Class1
    Set aApp.myApp = Application
End Sub

Sub UnTest()
    Set aApp = Nothing
End Sub

The question is how to convert that VBA codes to vb.net codes with windows form application?

Best regards...

Another link...
http://www.mrexcel.com/forum/excel-q...-instance.html

[westconn1]

the code posted above does not do what you want, read the follow ups, it only prevents the opening of a workbook in the same instance of excel

the last post in the thread may do so and could be converted to .net easily enough, but would use a timer or similar type loop to detect new instances at whatever interval, or with an addin, you could call the code in a workbook open event

it should also be possible to monitor processes, with a callback when a new process is created, not that i have done that

a search on monitor processes with callback, will return many results

[Herry Markowitz]

the code posted above does not do what you want, read the follow ups, it only prevents the opening of a workbook in the same instance of excel

Yes you are right. The code I posted prevents opening second excel file not second instance.(Start > Microsoft excel).

it should also be possible to monitor processes, with a callback when a new process is created, not that i have done that
a search on monitor processes with callback, will return many results

Could you please provide a code for this?

Edit:
My main request is prevent opening second instance of excel at first.
I mean I dont want to close second excel as soon as opening...

[westconn1]

Could you please provide a code for this?

as i said above, i have never done this

a simple option is to use an addin or put code in the personal workbook to create an application object with events, then you can test for instances of excel in the application.workbookopen event like

Private Sub myApp_WorkbookOpen(ByVal Wb As Workbook)
    if GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\.\root\cimv2").ExecQuery("select * from win32_process where name='EXCEL.EXE'").Count > 1 then
        set prxl = GetObject(, "Excel.Application")
        fn = wb.fullname
        wb.close false
        prxl.workbooks.open(fn)
        set prxl = nothing
        myapp.quit

    end if

End Sub

this is not in anyway tested, it is an excel solution, that should use an addin, if you want an external solution, using .net, you would need to research my previous suggestion, using google or similar searches, to find who has done similar code

[Herry Markowitz]

Hi westconn1,
Thanks for code but I need a vb.net code for this...

[Siddharth Rout]

My main request is prevent opening second instance of excel at first.
I mean I dont want to close second excel as soon as opening...

This is how I would do it in VB.Net

Imports Excel = Microsoft.Office.Interop.Excel

Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim ExcelInstance As Integer = Process.GetProcessesByName("excel").GetLength(0)

        If ExcelInstance > 0 Then
            MessageBox.Show("Excel is running. You may not open a new instance")
        Else
            '~~> Define your Excel Objects
            Dim xlApp As New Excel.Application
            Dim xlWorkBook As Excel.Workbook

            xlWorkBook = xlApp.Workbooks.Open("C:\MyFile.xlsx")

            '~~> Display Excel
            xlApp.Visible = True
        End If
    End Sub
End Class

[Herry Markowitz]

Hi Siddharth,
Your code do one time check if excel is open or not.
I need everytime check if excel is open or not.
Because second excel can not to be opened until my project finished...
Maybe instead of everytime check code we need a code which provides preventing opening second excel?
Any other idea?

[Siddharth Rout]

I am not sure I understand. Where are you opening the 2nd instance of Excel from? VB.Net or somewhere else?

[Herry Markowitz]

I am designing excel sheets from vb.net.
I want user dont open another excel file during my project is running (during designing excel sheets from vb.net).

[Siddharth Rout]

Do you mean not allow the user to open Excel file manually while your application is running?

[Herry Markowitz]

Do you mean not allow the user to open Excel file manually while your application is running?

Yes it is.

[westconn1]

you should be trying to avoid the user upsetting your application, without locking them out of any part of their computer, or preventing them from running some application, you should find some alternative to what you are trying to do, i personally would look on your application with horror, if it tried to stop me using excel or any other application

[Herry Markowitz]

you should find some alternative to what you are trying to do

I found another way which makes mouse and keyboard disable but that way is the worst
If you have any other advice I will be happy to hear it

[Siddharth Rout]

I agree with Pete here. You should not try and change the User's setting without his/her approval. You can always pop up a message box alerting the user to not open another excel instance till the time your application has stopped finishing whatever it is doing. For example many of the application while installing tell you to close all windows... That is the right way to do it

[Herry Markowitz]

I want this because if user opens second excel then my application fails...
And if my application fails then it is not easy to fix errors...
That is why I want to be sure that user must not open second excel file!

[Siddharth Rout]

Why would a user open a second instance

1. When you as a programmer has instructed not to do it?
2. When the user knows that opening a second instance will hamper the installation?

Not that I don't know the answer to your question. I do but somehow I am not convinced of your intentions...

[Herry Markowitz]

All right.
If there is no solution of this problem lets stop here.
Thanks westconn1.
Thanks Siddharth.
Have a nice day.

[westconn1]

I want this because if user opens second excel then my application fails...

you should fix your application, not to fail

[Herry Markowitz]

it should also be possible to monitor processes, with a callback when a new process is created, not that i have done that
a search on monitor processes with callback, will return many results

Hi Pete,
Could you please provide a sample results for this?

[vbfbryce]

This may help:

https://social.msdn.microsoft.com/Fo...orum=vbgeneral

[Herry Markowitz]

Hi vbfbryce,
Thanks for the link.
But the code in the link is not dynamic code.
Because the code in the link doesnt run whenever Notepad opens.
But thanks anyway.

[FunkyDexter]

Seriously, you should not be preventing a user from running an application that has nothing to do with your own. That is hijacking the user's machine without their consent. Windows is going to fight you every step of the way and with good reason - if you were able to do this it would be a wide open door to installing and, more importantly, preventing the removal of, malicious code.

If your application fails when the user opens a second copy of excel then there is something seriously flawed in your application. Fix the flaw.

What, exactly, causes your application to fail? There is nothing about just opening excel that would cause a fail. So what, exactly, are you trying to do with excel and what is the user interaction that causes it to fail.

[Herry Markowitz]

Hi Funky,
According to following reasons I am insist on preventing opening second instance of excel or minimize excel whenever user try to open excel.
1- If user clicks any excel cell then my application fails.(And there will be some errors which are not easy to clear)
2- I dont want users see my excel formulas and excel objects which I am using in order to avoid my idea and my formulas are being copied.
Any idea?

[vbfbryce]

Have your app work in its own instance of Excel, and have it stay hidden.

[Herry Markowitz]

My app designed work with excel.
That is why I want to prevent opening second instance of excel or minimize excel.
I dont want to hide excel because some codes doesnt work when excel is hidden.

[westconn1]

1- If user clicks any excel cell then my application fails.(And there will be some errors which are not easy to clear)

no excuse for this, fix it

2- I dont want users see my excel formulas and excel objects which I am using in order to avoid my idea and my formulas are being copied.

lock the appropriate worksheets and VBA projects, or create all at runtime

[vbfbryce]

"...some codes doesnt work when excel is hidden."

Maybe this can be fixed.

[FunkyDexter]

no excuse for this, fix it

lock the appropriate worksheets and VBA projects, or create all at runtime

Maybe this can be fixed.

I agree with all these statements.

What errors are you getting? What code throws the error? What doesn't work when it's hidden? I guarantee you that it will be easier to fix these errors in your code than it will be to take control of the users machine. Taking control of the users machine is something your user will not want you to do and something that Windows will actively try and prevent you from doing because it represents a massive security risk. None of us are going to help you do it for exactly the same reason - it would be a hacker's delight. When you need to enter a house you use the right key in the front door - you don't start smashing the Windows.

[westconn1]

you don't start smashing the Windows.

lol, i like this

[Herry Markowitz]

My question is very simple.
Please do not make my question so complicated.

Let me summarize my question again;
Following code minimizes excel.
I need dynamic version of following code.
Dynamic code means the code must work whenever user try to open second excel during my app is running!

 Dim ExcelApp As Excel.Application
        ExcelApp = GetObject(, "Excel.Application")
        ExcelApp.WindowState = Excel.XlWindowState.xlMinimized

I tried to use application event for dynamic code but couldnt succeded.
Look at this;
http://prntscr.com/990rqi

[FunkyDexter]

And the answer's very simple: you can't.

[vbfbryce]

This is what I'd use to open an instance "in the background" that your users would not (easily) be able to stumble onto:

Dim oXLApp As Excel.Application
        Dim oXLBook As Excel.Workbook

        oXLApp = New Excel.Application

        'oXLApp.Visible = True  don't make it visible, nor minimized

        oXLBook = oXLApp.Workbooks.Open("c:\yourPath\testDotNet.xlsx")

If I run this, then open a 2nd instance of Excel manually, it has no impact on the code I run after the above.

[FunkyDexter]

+1 to the suggestion above. You can run your own code in an isolated instance. What you can't do is stop the user from using their machine.

[FunkyDexter]

In light of your last post (which I have deleted) I am closing this thread