question about proposed feature for Xvnc

"Beerse, Corné" cbeerse "at" hiscom.nl
Mon, 25 Mar 2002 09:00:18 +0000


> -----Original Message-----
> We were faced with a problem of using Xvnc to provide
> a single application to a significant number of users.
> We were trying to deploy an industrial application that
> would start every time a user connects to the Xvnc
> (via inetd) without asking the user to login through
> the XDM.

Nice thinking. The general unix aproach for this is to create dedicated
users for the task: just login as the user and the task starts. This is
frequently used on terminal/telnet base.

With the -inet option, you can extend this to the windows environment:
arange the account to start the app as soon as the 'user' logs in.

> 
> In collaboration with Lee Allen <lee "at" leadtec.com>
> we have developed a patch for Xvnc. The patch adds
> a new command line option ("-startapp"), which should
> be used together with the "-inetd" option. Command
> specifies the application to be run by Xvnc once
> it starts up.

It is reasonable thinking to use a -startapp but what do you do with the xdm
options (-broadcast, -query...)? Do you need a window manager? IF the
startapp also has subwindows (show me an X11 app which has none), then you
need the windowmanager to rearange the windows within the vnc screen.

I can think of many more of these questions and to solve them, you end up
rebuilding your own windowmanager. And now I write this, the app can easily
be ~/.vnc/xstartup (even default to it?) to have the same usage as with the
vncserver startup script.

Hence: make the -startapp disable the xdm options.

> 
> In addition, code responsible for connection
> through inetd was modified to add support for
> SO_KEEPALIVE (to ensure that Xvnc shuts down once
> the peer client is gone)

What do you do once the connection is gone? Just kill the Xvnc? or also kill
the started application? (and all it's childs?) One of the not-so-nice parts
of Xvnc is that if the viewer dies, the server or one of the apps always
leaves some coredump. Hence a -trap option would also be nice: What should
be done if the viewer dies and the server goes down too?

> 
> We tested the patch on our systems
>    - Linux,
>    - SCO Open Server 5.0.6
> 
> We would like to solicit feedback about usefulness
> of this feature. If it is considered useful what
> are common ways of making this patch available?
> Is posting it to the list an acceptable practice?
> (it is only 23k).

Do not get confused on my reply, you just made me thinking in various
directions,

> 
> Best Regards,
> Anthony Oganesian
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