Progress on preventing multiple instances of a program fromrunning in windows

[Gordon Tillman]

Makes sense Jonathan!

I would be interested in knowing how that works out..

--gordon

On Dec 3, 2004, at 09:31, Lynch, Jonathan wrote:

> I thought about something like that - but was concerned that the app
> would not know if the value had been changed in the file, and then
> terminated. That would not matter if the program is running as a 
> visible
> window, because the user could just see that the window is not open, 
> and
> tell the program to go ahead and run anyway.
>
> However, I need to use this for a program that will run invisibly. If 
> it
> is running invisibly, then most users will not know how to check for
> running processes to determine if the program really is running.
>
> Using sockets allows for the program to see if it is running. My plan 
> is
> to make it so that if it is already running, the second instance will
> check to see that the first instance is responsive, then when it
> confirms that it is working, it will tell the first instance to make
> itself visible. Then the second instance will turn itself off.
>
> This way, the program can run invisibly, but whenever the user clicks 
> ontthe icon (which will be automatically inserted into the start menu) 
> the
> program will just appear on the screen. The user can then change
> preferences and close it, and it goes back to running invisibly. (With 
> a
> separate button for shutting down the program, so the user does have 
> the
> option to turn it off, if desired)
>
>
> -----Original Message-----
> From: use-revolution-bounces at lists.runrev.com
> [mailto:use-revolution-bounces at lists.runrev.com] On Behalf Of Gordon
> Tillman
> Sent: Friday, December 03, 2004 10:13 AM
> To: How to use Revolution
> Subject: Re: Progress on preventing multiple instances of a program
> fromrunning in windows
>
> Howdy Folks,
>
> I'm jumping in on this thread a bit late, but I wanted to let you know
> what we are doing to handle this issue.
>
> I have a preferences library that any application can use to manage,
> well, preferences.  It does the right thing and stores the preferences
> at the proper location for mac, windows, and linux.
>
> During the application startup code, before I start opening sockets but
> after having initialized the preferences, I check for the presence of a
> preference called "running" that has a value of "yes" or "no".
>
> If the preference has a value of "yes", then the application displays a
> message to the effect of "It appears that another instance of this
> program may be running.  That can also be caused if it had terminated
> abnormally before.  Do you wish to continue starting up?"  The user can
> click Yes or No.
>
> Normal operation is as follows:
>
> Application starts up.  Checks the pref.  Sets it to "yes" and saves
> preferences (to flush the updated value out to the file).  The on
> shutdown handler sets the value back to "no".
>
> --gordon
>
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