Restricting Multiple Sessions of A5

[Dale Bradt]

I was wondering if there is a simple way to restrict a user to have only one session of A5 of a particular application open at one time. I have searched for this subject but have found nothing.

Any ideas would be appreciated.

Dale

[Stan Mathews]

RE: Restricting Multiple Sessions of A5

Your autoexec script could try to obtain exclusive use of a table that gets opened when your startup form is opened. Failure to obtain exclusive use would cause the sctipt to abort and close the instance of Alpha.

This would require

an autoexec script
a startup form that was always open
a table that could remain in use while the app was in use (could be a dummy table with no other purpose)

[Dale Bradt]

RE: Restricting Multiple Sessions of A5

Stan,

That's not quite what I'm looking for. It's okay for several users to be accessing the application from their own PC's. What I want to restrict is any one PC or User from having more then one session of A5 open on their Windows desktop with the same application running.

Dale

[Stan Mathews]

RE: Restricting Multiple Sessions of A5

It is not clear if you want to keep a user from accidentally opening two sessions or want to absolutely prohibit it.

You could use a routine in the autoexec to

open a table
check a flag field to see if the app is in use
ask the user if they really want two sessions open
abort if they don't
write an in use flag to the field if it was not in use.

You would have to control the exit process to make sure the flag was removed when the app was exited.

If you don't use the ask the user portion above, they couldn't get back in if they had a system crash and the flag was not erased.

[Dale Bradt]

RE: Restricting Multiple Sessions of A5

Stan,

That sounds like a winner. I was thinking along those lines but came up with the crash senerio. I think asking the user should take care of that issue.

Thanks for your suggestions.

Dale

[PhilD]

RE: Restricting Multiple Sessions of A5

Dale,

Ray Lions posted this script awhile back to prevent a user from opening two copies of the same app. It uses a text file to keep track. If there was a crash, it will let the user back in after answering the dialog. It goes in the autoexec script and you need a 'menu' or default welcome form that opens when you start the app to keep things from crashing as explained below. This may be what your looking for.

Msg ID:	34931
Subject:	RE: prevent 2nd copy from opening
Author:	Raymond Lyons
Date:	06-27-2003 5:10 PM
File:	
As I said above, I have 2 running right now on A5v5 full. 

Your concern about a crash can be handled with my text file suggestion as long as your app has a master menu that it starts from and all other forms eventually come back to it. Example code follows. 

Ray Lyons 

'Date Created: 27-Jun-2003 12:50:50 PM 
'Last Updated: 27-Jun-2003 02:00:56 PM 
'Created By : Ray Lyons 
'Updated By : Ray Lyons 
dim filename as c 
filename = "C:\A5chk.txt" 
result = file.exists(filename) 
if result = .F. then 
file.create(filename, FILE_RW_EXCLUSIVE) 
goto continue 
else 
result2 = ui_msg_box("Application Load Halted","This application is either already running (check to see if it is minimized on your task bar) or you have you experienced a shut down from a crash. Have you experienced a crash?",UI_QUESTION_SYMBOL+UI_SECOND_BUTTON_DEFAULT+UI_YES_NO) 
If result2 = UI_NO_SELECTED 
A5.Close() 
end 
else 
goto continue 
end if 
end if 
continue: 
'Put res of autoexec here or just end here or put an END up where continue is. 
end 
'Now, for this to work you ned a master menu form that all other forms 
'comes back to when they are closed. 
'Then in the CanExit event for the master menu put: 
'Cancel() 
'The master menu form will then need a Close button with: 

'dim filename as c 
'filename = "C:\A5chk.txt" 
'file.remove(filename) 
'A5.Close()

Phil DeGruy

[martinwcole]

RE: Restricting Multiple Sessions of A5

look in the code archive

[Dale Bradt]

RE: Restricting Multiple Sessions of A5

I didn't think of looking there. I have added the code from the archive to my autoexec and all seems to work.

Thanks to all that contributed to this post.

Dale

[Raymond Lyons]

RE: Restricting Multiple Sessions of A5

Martin,

I looked at what you posted in code archive. I am sure it works. However, I can't imagine how it could be preferable to my code that Phil posted above. Am I missing something or or in your scenarion is one supposed have Word (or any apps file for that matter) open whenever the app is running? Is so, I can't imagine how that is a desirable thing to do.

Ray

[Dale Bradt]

RE: Restricting Multiple Sessions of A5

Ray,
I thing your looking at the wrong post in the archive. It's the post below the one that speaks of word.

Dale

[Jim Chapman]

RE: Restricting Multiple Sessions of A5

Hello Dale,

Check out the sys_id_enum() function in the documentation. There is an example showing how to do exactly what you want, if I am understanding correctly.

Good luck,
Jim

[martinwcole]

RE: Restricting Multiple Sessions of A5

Yes, Jim, I like that, but you have to decide what you want to close. If you leave in the sys_focus_put you will close the existing copy that was already open, but if you omit it, you close the copy that is trying to open.

Personally, its the 2nd one I want to close.

[Raymond Lyons]

RE: Restricting Multiple Sessions of A5

Martin,

Sorry for my comment above. I failed to take the time to grasp what your code was doing. Should have known better (you are not in the habit of posting things I "can't imagine" the reason for!).

Ray

[martinwcole]

RE: Restricting Multiple Sessions of A5

hi Ray.

There is a minor problem with my script, and the one Jim was referring to - namely, that if you have some other something with the same name as your alpha window (like a word document) the script fires, and you cannot open the first copy ogf your app if the other document is already open, as the "window name" is what is being opened twice - thus I have to be sure that the name I use is unlikely to be used again.

If I could figure out how to distinguish whether the window is an "alpha" window or not, it would be perfect.

[Raymond Lyons]

RE: Restricting Multiple Sessions of A5

Yes, I can see that now, and it would be good if there is a way because with a large number of users the chance of someone naming an open doc with the same name goes up--though still not very likely. Anyway, the method I posted (as well as other ways using a flag in a table) does not have the same problem, is simple and quick. However, it does make use of something some might not like--users having to come back to a startup menu form in order to close A5. On the other hand, I find that "feature" to be a good one because otherwise users (including me) have a tendency to accidentally close A5 by clicking on the wrong X. But of course the latter "feature" can be implemented even under the code you posted. Maybe v6 will provide a better way.

Ray