Share My Creation B4J single instance

I wanted to limit my app to running as a single instance, in both Windows and Linux.

Several solutions for this single instance problem have been posted, but usually do not include running in Linux.

Erel made a few suggestions in one of his posts. One of these was to use an external file as a marker to indicate that the app is already running.

I took on the task of doing this, and here is my solution.

The "single_instance_test" example attached has many comments which describe how the app works.

 

[Erel]

Nice solution with the timer!

 

[niewd]

Thanks Erel.

 

[rraswisak]

Hi,

This trick is work if you execute same jar file at the same path, if you run the second jar from different path then the trick does not work.

I have better way to implement single instant of running app, which is by opening specific port at first load, here the code:

Sub Process_Globals
   Private fx As JFX
   Private MainForm As Form
   Private xInstance As UDPSocket '<--- from jNetwork library
End Sub

Sub AppStart (Form1 As Form, Args() As String)
   MainForm = Form1
   Try
       xInstance.Initialize("",12340,0) '<--- change the unique port as you want
       Log("Form ready")
       MainForm.Show
   Catch
       fx.Msgbox(MainForm, "Application already running !","Attention")
       ExitApplication
   End Try
End Sub

Regards,

 

[JackKirk]

I have better way to implement single instant of running app, which is by opening specific port at first load, here the code:

Sub Process_Globals
Private fx As JFX
Private MainForm As Form
Private xInstance As UDPSocket '<--- from jNetwork library
End Sub

Sub AppStart (Form1 As Form, Args() As String)
MainForm = Form1
Try
xInstance.Initialize("",12340,0) '<--- change the unique port as you want
Log("Form ready")
MainForm.Show
Catch
fx.Msgbox(MainForm, "Application already running !","Attention")
ExitApplication
End Try
End Sub

What a beautifully simple elegant bit of code - have implemented it on all my AWS EC2 and remote site PC B4J apps.