Network - Running A Standalone Application From A Network Server

[Frank D. Engel, Jr.]

On Dec 17, 2004, at 6:08 AM, Ben Rubinstein wrote:

> on 17/12/04 10:44 am, John Miller wrote
>
>> 1. Can a standalone stack, running on a server, actually be used by
>> more than 1 person at a time without problems?
>
> Probably not.  There may be a difference between operating systems 
> here.  On
> Mac (classic) an app can only be once; the file on disk corresponding 
> to the
> application is locked while the application is open.  On Windows (in
> general) apps are loaded into (at least virtual) memory, and an app
> corresponding to a file on disk can be open multiple times.  On MacOS 
> X I'm
> not sure; I know that an application writing to itself, possible on Mac
> Classic but not on Windows (which corresponds to their respective 
> positions
> as to whether the running app uniquely owns the file it sprang from) 
> is not
> possible on X; however, it doesn't appear that an X app can be open 
> twice.
> Someone who knows what they're talking about may be able to give more 
> detail
> here.

An OS X program can have multiple running instances.  Additionally, 
Fast User Switching in OS X 10.3 allows several users to be logged in 
simultaneously on the same computer.  Having one user running a 
particular program does not prevent other users from running it at the 
same time.  It's partially due to the UNIX clone sitting under OS X.

Note that in general, trying to start a second instance of the same 
program within a single user login session from the GUI doesn't work: 
the behavior is the same as for OS 9.  But you can start a new instance 
from a terminal window just fine.

>
>> 2. Related Question: When somebody opens this stack on the server. Is
>> it actually running on the stack, or does the program run on the
>> indivual's computer?
>
> Not quite clear about your situation.  Two possibilities:
> - there is a standalone on the server.  User has a share mounted from 
> the
> server, and launches the standalone from that network drive.  In that 
> case,
> it's running on the individual's computer; but it may be still 
> accessing the
> network drive (the operating system may not simply load everything 
> into the
> memory of the user's computer, it may still read some parts off the
> (network) disk).
> - there is a stack on the server, and the users have either the 
> revolution
> app, Dreamcard Player, or a simple 'launcher' standalone on their 
> machines.
> In this case, it's simpler; the app (whichever of the three) is 
> running on
> the user's computer: when the app opens a stack from the server, the 
> whole
> stack is read into memory (on the user's computer).
>
>> 3. Related Question: When a person is working on an estimation 
>> project,
>> all the values for that project are temporarily stored in various
>> fields within revolution. This info is later saved on a server as a
>> text file. Am I correct in assuming that if more than 1 person is
>> running the app off the server, if indeed this is possible, that it
>> could create quite a mess?
>
> Fields within a stack shouldn't be a problem.  This always takes place 
> in
> memory, which will always be on the user's computer.  (I'm assuming 
> you're
> not doing anything exotic like Citrix in all of the above, btw.)
>
> When you save the data to the server, you obviously need to take 
> precautions
> against one user overwriting another user's data, or one user being 
> locked
> out by another.

In other words, if the same file is always used, you've got some 
potential issues.  If a different file is used each time (or for each 
user, perhaps), there shouldn't be a problem here.

>
>> 4. Related Question: Since this is a new program, I am coming up with 
>> a
>> new version at least twice a week. If having several people running 
>> the
>> stack off the server is not possible, is there a way to quickly update
>> the stack on everybody's individual computers with a newer version?
>
> I don't think the stack off the server should itself be a problem.
> Revolution, or any standalone built round it's engine, will read a 
> stack
> into memory completely and operate on it there.  Problems may be if 
> you're
> not talking about a stack off the server, but about a standalone off 
> the
> server; and when it comes to saving data.
>
> In terms of quickly updating the stack, you can build a 'shell' 
> standalone
> which doesn't do much except start up, and open a stack containing all 
> the
> good stuff of your app.  (These are sometimes referred to as 'splash 
> screen'
> standalones, since they often display a splash screen and then pretty 
> much
> hand over to the stack with the real stuff.)  Depending on your setup, 
> this
> could be a stack loaded each time off a file server; a stack loaded 
> each
> time from a web server; or a stack loaded from a local copy, with some
> provision to check for updates, and download and replace the local 
> copy.
>
> HTH,
>
>   Ben Rubinstein               |  Email: benr_mc at cogapp.com
>   Cognitive Applications Ltd   |  Phone: +44 (0)1273-821600
>   http://www.cogapp.com        |  Fax  : +44 (0)1273-728866
>
> _______________________________________________
> use-revolution mailing list
> use-revolution at lists.runrev.com
> http://lists.runrev.com/mailman/listinfo/use-revolution
>
>
-----------------------------------------------------------
Frank D. Engel, Jr.  <fde101 at fjrhome.net>

$ ln -s /usr/share/kjvbible /usr/manual
$ true | cat /usr/manual | grep "John 3:16"
John 3:16 For God so loved the world, that he gave his only begotten 
Son, that whosoever believeth in him should not perish, but have 
everlasting life.
$



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