Network - Running A Standalone Application From A Network Server

[Ben Rubinstein]

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.

> 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.

> 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