[launchd-dev] An agent with Keep-Alive set to true (in this agent's plist)

[Nick]

Hi Jerry,
Thank you for the response.
But what differs an application from a command line application? How launchd
realizes it's an application? By presence of an application bundle? Of a
plist? Instantiating NSApplication object? Some other ways?


2011/6/10 Jerry Krinock <jerry at ieee.org>

>
> On 2011 Jun 09, at 14:04, Nick wrote:
>
> > Is there any way to solve this issue?
>
> This may not be a "solution", but just to clarify, I think the problem
> comes about because the process you're keeping launched all the time is an
> *application*.  I use "KeepAlive" for a command-line tool and don't have
> this problem.
>
> It's possible that Apple designed it this way on purpose; indeed it would
> be quite odd to have an *app* which the user could not quit.  And if your
> app is, as you say,
>
> > (this is a kind of child protection system)
>
> it seems that it might be better off as a background process which the
> child does not see.
>
> Alternatively, you could write a little command-line tool which would do
> what launchd does, watching for your app to quit (this can be done by
> registering for NSWorkspaceDidTerminateApplicationNotification and entering
> a run loop) and then relaunching your app whenever it quits.  Then you would
> have launchd launch this command-line tool instead of your app.
>
> I've written such a tool which watches for apps to quit.  Here is its
> main():
>
> int main(int argc, const char *argv[]) {
>    NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init] ;
>
>    [[NSUserDefaults standardUserDefaults] addSuiteNamed:@"com.myCompany.myApp"]
> ;
>
>    // Create a run loop
>    NSRunLoop* runLoop = [NSRunLoop currentRunLoop] ;
>
>    // Create a Quatcher, which will add an observer
>    Quatcher* quatcher = [[Quatcher alloc] init] ;
>
>    [runLoop run] ;
>
>    [quatcher release] ;
>    [pool release] ;
>
>    return 0 ;
> }
>
> The "Quatcher" class is my "Quit Watcher".  I'll post its code if you
> request it.
>
> Think about your design.  You probably don't want an app that never quits.
>  What you probably want is an app which sets some user defaults, loads a
> launchd task to "KeepAlive" a helper tool, and is then quit.  Your app's
> package will contain the kept-alive background helper tool which will do the
> work 24/7 as directed by the app's preferences.  It's a little more tricky
> design.  Read the message I posted yesterday in answer to a similar question
> on cocoa-dev:
>
> http://lists.apple.com/archives/Cocoa-dev/2011/Jun/msg00245.html
>
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