Application as Singleton

Hi,
Sorry if this has been answered before, I just couldn't find it.
What are the available choices for ensuring that the user cannot open
two instances of my application?
Which is the recommended one?

Any help woulb be appreciated.

Regards,
Daniel

Hi


take a look at
SessionManager>> allowDuplicate
allowDuplicate
 "It would appear that the image associated with this session is already
open. Take action
 appropriate to the policies of the receiver. Answer whether to continue the
session.
 The default is to carry on brazenly."

 ^true


off course you would make your own  suclass off  RuntimeSessionManager
  and reimplement  allowDuplicate


Best regards
Marcelo Diaz Cortez

"Daniel Rozzeta" <[hidden email]> escribió en el mensaje
news:[hidden email]...

Daniel

You wrote in message news:[hidden email]...
> Hi,
> Sorry if this has been answered before, I just couldn't find it.
> What are the available choices for ensuring that the user cannot open
> two instances of my application?
> Which is the recommended one?

Simply override #allowDuplicate in your SessionManager subclass to answer
false, which will cause the second instance to exit immediately. See
DevelopmentSessionManager for a slightly more sophisticated example.

Regards

Blair

Hi,

Blair McGlashan wrote:
>
> Simply override #allowDuplicate in your SessionManager subclass to
> answer false, which will cause the second instance to exit
> immediately. See DevelopmentSessionManager for a slightly more
> sophisticated example.

FWIW: I was playing around with this recently and wanted to stop the same
user from running a second instance, but allow XP fast switching between
different users.

According to MSDN, "Fast user switching is implemented using Terminal
Services sessions.", and from:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/termserv/te
rmserv/kernel_object_namespaces.asp

I use the following for the event name:

sentryEventName
| eventName |
"#pathFromCSIDL is implement in the Shell packages"
eventName := (ShellFolderLibrary default pathFromCSIDL: CSIDL_APPDATA)
copyReplacing: $\ withObject: $/.
(OSVERSIONINFO current isNT and: [OSVERSIONINFO current isNT4 not])
ifTrue:
  [  "This is 2k, XP or 2003
         The name can have a Global\ or Local\ prefix to explicitly create
         the object in the global or session name space. The remainder of
the name can
         contain any character except the backslash character (\). "

      eventName := 'Global\' , eventName].
^eventName! !

Would this be a better default for applications that only write to user
paths?

Thanks,
Steve
--
Steve Waring
Email: [hidden email]
Journal: http://www.stevewaring.net/blog/home/index.html

Whoops,

> (ShellFolderLibrary default pathFromCSIDL: CSIDL_APPDATA)

should be:

(ShellFolderLibrary default pathFromCSIDL: CSIDL_APPDATA) , self
imageFileName

(or something the identifies the app per user)

Steve
--
Steve Waring
Email: [hidden email]
Journal: http://www.stevewaring.net/blog/home/index.html

Blair and Marcelo,
Thanks.  It was right in front of my nose, wasn't it?

Great community and product,
Daniel


"Blair McGlashan" <[hidden email]> wrote in message news:<bge9fi$ntit5$[hidden email]>...

"Steve Waring" <[hidden email]> wrote in message
news:bgell5$mtr3o$[hidden email]...
Steve, I must be missing something here because by default "global" (small
G) kernel object names are actually session local unless specifically
prefixed with "Global\" (big G). In other words the Win32 Event name that
Dolphin uses (a canonicalized "image" name) will be unique within each user
session for a particular application (or image), and so it should prevent
the same user running a second application instance, but not prevent another
user from doing so. Certainly this is demonstrably the case with the
development environment, although ironically in that case it should perhaps
be using a Global event name to prevent conflict over the change log and
image files. Perhaps this is the sort of thing you are getting at, and in
fact I'm not sure there is one policy here that would suit all applications.
I'd rather stick with TSTTCPW in the base and in the next patch level we'll
refactor out the generation of the sentry name so that it is easier to
specialise.

Regards

Blair

Hi Blair,

> Steve, I must be missing something here because by default "global"
> (small G) kernel object names are actually session local unless
> specifically prefixed with "Global\" (big G).

Yes, you are right. However, while prefixing the name with "Global\" may not
be necessary for XP fast-user switching, it may be necessary for Terminal
sessions. Without being able to test this, I assume the same user could be
running multiple sessions, and using the "Global\" prefix would stop the
application from running in more than one of those sessions.

> In other words the
> Win32 Event name that Dolphin uses (a canonicalized "image" name)
> will be unique within each user session for a particular application
> (or image), and so it should prevent the same user running a second
> application instance, but not prevent another user from doing so.

OK, I see this now. This would be what that MSDN page describes as:

   "Note that the more common case of running the
   "application once per session is supported by
   " default since the named object is created in a
   "per session namespace."

> and in fact I'm not sure there is one policy here that would suit all
> applications. I'd rather stick with TSTTCPW in the base and in the
> next patch level we'll refactor out the generation of the sentry name
> so that it is easier to specialise.

That would be handy, but after reading your message, I think I have made a
mountain out of mole hill :) I had a user tell me that they were running
my application on 2003 using terminal sessions and I came across that
"Kernel Object Namespaces" MSDN page researching the implications of that.
Using my sentry name would only be necessary in the case of the same user
name being active in multiple sessions, and I dont know enough about
terminal services to know if that is a rare or impossible case.

Thanks!
Steve
--
Steve Waring
Email: [hidden email]
Journal: http://www.stevewaring.net/blog/home/index.html

Steve and Blair,
"Steve Waring" <[hidden email]> wrote in message
news:bgpb2g$r8ssu$[hidden email]...
[...] Without being able to test this, I assume the same user could be
> running multiple sessions [...]
That is indeed possible.  In Windows Server 2003, there's a checkbox for the
feature; by default, users aren't restricted to a single session.  I think
it's also possible on 2000 and using Citrix Metaframe.  Nevertheless,
considering that most organizations use Terminal Server (or Citrix Systems'
enhanced version) to save resources, it seems unlikely that many would allow
users to log on to multiple sessions.  Of course, we do with ours, but we're
different--and I'm the only one who uses it ;^).

Don