limiting multiple running instances of the same vb.net 2003 application??

Experts,
How can I limit the number of the same vb.net programs running to 1.   I developed an application in vb.net 2003, and created a setup project for the application.  The setup puts a short cut on the users desktop.  Every double click of the short cut opens another instance of the same program.  I don't want this to happen.  If for example the user  opens the application and minimizes and forgets that it is already running, I need the short cut to pull up the already running application.  Is something like this possible?
tentavariousAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Mike TomlinsonMiddle School Assistant TeacherCommented:
Sure it is...        (it's even easier in VB.Net 2005)

Public Class Form1
    Inherits System.Windows.Forms.Form

    Private Const SW_SHOWNORMAL As Integer = 1

    Private Declare Function IsIconic Lib "user32" _
        (ByVal hWnd As IntPtr) As Integer
    Private Declare Function ShowWindow Lib "user32" (ByVal hWnd As IntPtr, _
        ByVal nCmdShow As Integer) As Integer
    Private Declare Function SetForegroundWindow Lib "user32" _
        (ByVal hWnd As IntPtr) As Integer

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim appName = System.IO.Path.GetFileNameWithoutExtension(Application.ExecutablePath)
        Dim ps() As Process = Process.GetProcessesByName(appName)
        If ps.Length > 1 Then
            Dim mainHandle As IntPtr = ps(0).MainWindowHandle
            If IsIconic(mainHandle) <> 0 Then
                ShowWindow(mainHandle, SW_SHOWNORMAL)
            End If
            SetForegroundWindow(mainHandle)
            Application.Exit()
        End If
    End Sub

End Class
0
tentavariousAuthor Commented:
Ok that works,  I also found this code that works,  my problem know is that if the first app is minimized how can i show it in it's normal window state if the short cut is double clicked again?

form load event
  If Not (Me.RunningInstance Is Nothing) Then
         MessageBox.Show("This application is already running")
          duplicate_app = True
           Me.Close()
          Exit Sub
        End If

 Public Shared Function RunningInstance() As Process
        Dim current As Process = process.GetCurrentProcess
        Dim processes As Process() = process.GetProcessesByName(current.ProcessName)
        For Each process As Process In processes
            If Not (process.Id = current.Id) Then
                If Reflection.Assembly.GetExecutingAssembly.Location.Replace("/", "\") = current.MainModule.FileName Then
                    Return process
                End If
            End If
        Next
        Return Nothing
    End Function
0
Mike TomlinsonMiddle School Assistant TeacherCommented:
"my problem know is that if the first app is minimized how can i show it in it's normal window state if the short cut is double clicked again?"

All of that is taken care of in my example above...
0
Cloud Class® Course: Microsoft Office 2010

This course will introduce you to the interfaces and features of Microsoft Office 2010 Word, Excel, PowerPoint, Outlook, and Access. You will learn about the features that are shared between all products in the Office suite, as well as the new features that are product specific.

tentavariousAuthor Commented:
It doesnt work, I am using a notifyicon, so that my app only appears in the tray bar.  When I use your method and try to load a second application i just get a quick screen flicker and the original app stays in its minimized state.
0
Mike TomlinsonMiddle School Assistant TeacherCommented:
"It doesnt work, I am using a notifyicon"

Well of course it doesn't work then!...an icon in the system tray is NOT the same as a minimized form.

"Waking up" an app from the system tray is significantly trickier in VB.Net 2003 as you must write custom interprocess communication code.  Doing this in VB.Net 2005 is a snap.

Basically you have to send a custom message using Win APIs to the previous app and trap it in the main forms WndProc() method.  You want to go that route?...
0
tentavariousAuthor Commented:
Nah, as long as two of the same applications are not opening up.  Which code is more efficient mine or yours?  I don't use a lot of win api functions, because I don't know many.  How do you find a list of windows functions, do you just know them from experience with other programming languages?
0
Mike TomlinsonMiddle School Assistant TeacherCommented:
Sorry...I just know them from experience...

If you just want to prevent multiple instances then it can simply down to:

Public Class Form1
    Inherits System.Windows.Forms.Form

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(Application.ExecutablePath)).Length > 1 Then
            Application.Exit()
        End If
    End Sub

End Class
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Visual Basic.NET

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.