Look-Over-Your-Shoulder Tool
Dongmin Kim
Look-Over-Your-Shoulder application provides integration of the
VNC screen sharing capability
with Tango Interactive session control. It seamlessly
integrates TI event sharing collaboration model with the
ability to share a screen of arbitrary machine with
all or selected participants of a TI collaboration
or distance learning session.
VNC provides the basic functionality enabling
platform-independent screen sharing between machines.
The machine willing to share the screen and (optionally)
access to the keyboard and mouse must run VNC server.
One or many VNC clients can then connect to this
server so that their users can see the screen of the
remote machine and can use it's graphical interface
as they would be using it locally - modulo network
delay and generally lower performance (slower response
time).
VNC is typically used in two situations: (1) one can
remotely use the machine, for instance for system administration
access. This is a very important application for PC platforms
which do not support functionality equivalent to the UNIX X
Server. (2) It is possible to use VNC in the CSCW application
context, i.e., one can run an application on one machine
and have it seen or manipulated by multiple remote machines.
Our integration of VNC with Tango Interactive framework
addresses both these aspects, and it adds all necessary
session managemnt, access security, and local and remote
application startup capability to the usual VNC features.
Together, TI and VNC provide a truly break-through flexibility
in using screen sharing as a component of a multi-function
collaboratory system.
Tango Interactive supports two application modules
using VNC as a component: Look-Over-Your-Shoulder (this application)
and Share-A-Screen (find it in your application
menu!). The remainder of this help file describes
Look-Over-Your-Shoulder functionality.
Look-Over-Your-Shoulder lets the instructor, collaboration
session chairperson, or a support person to see and (optionally)
manipulate the screen of other participants of
Tango Interactive collaboration or distance learning session.
This functionality is used to (1) enable instructor or chairperson
to observe hands-on work done by students or meeting participants;
and (2) provide support personnel of the ASP site with a tool to troubleshoot
session problems or to help users to learn how to properly use
the entire collaboration or distance learning setup.
NOTA BENE: Look-Over-Your-Shoulder is ONLY available on PC
machines. UNIX support will be added eventually.
Starting the Look-Over-Your-Shoulder application session:
- Select Look-Over-Your-Shoulder from the Applications menu. You will
get a start-up window.
- Only users with certain roles in the system, or users explicitely
named in the application configuration files can start LOYS application.
If you are not authorized, the system will show a message and the session
will not ben created. Consult TI Application Server Guide for help
with setting up this functionality on your site.
- If you are authorized to start the session, you will get a start-up
window showing a list of users whose displays can be connected to.
This list is initially empty. Don't panic - this is expected behavior.
- Use the TI "Remote Join" operation to start the LOYS session
on the machines of all users your would like to monitor. The users can also
join this session on their own, using the TI "Join" operation. As the
users join (by either method), their names will be added to the list
in the LOYS startup window.
- On all machines of the users joing this session, an instance of
"tangoVNC" server is automatically started. This instance is protected
by a password known only to the application. No other users can connect
to these VNC server instances. tangoVNC server instances will be
shut down upon termination of the LOYS session. tangoVNC is a slightly modified
original VNC server. Upon startup, the VNC icon will appear in the trays
of all users connected to the LOYS session.
- Once a user joined the LOYS application session, his/her display
can be monitored by the authorized personnel. Normally, non-authorized
users cannot monitor any remote displays, although this behavior can be
overriden by modifying authorization files on the TI Application Server.
- To take "a look over somebody's shoulder", select the name of the
user from the LOYS startup window and click "Connect" button. tangoVNC
client (a Java applet) will start and it will let you monitor user's
display.
- Miltiple authorized users can concurrently monitor display
of one user. Further, authorized users participating in one LOYS
application session can monitor displays of different users. This
allows for a setup of break-up sessions, or for concurrent
troubleshooting of multiple remote machines/users.
- The startup window remains on the authorized user screen for
the entire duration of the LYOS application session. You may minimize
this window, but DON'T kill it! If you do, your Look-Over-Your-Shoulder
session participation will be terminated, or, if you are session master,
the entire LOYS application session will be removed!
- Although it is technically possible to start multiple LOYS sessions,
it is not recommended and there is no reason to do so. No new
functionality results form having multiple concurrent LOYS application sessions.
Bugs, caveats, limitations:
- If the users don't see "VNC" icon in the tray after they joined
the LOYS application session, their TI client installation may be
faulty, or they did not get the tangoVNC local module with it.
Contact us.
- VNC has a very limited scalability. An average workstation
won't be able to share its display with more than a handful
of remote users. As students workstations may be relatively
low-end, be carfull not to let too many authorized users to
monitor their displays concurrently, or the user machine will become
very sluggish. A nervous user can easily crash the system under such
circumstances.....
- All software modules used in the appliation are distributed
under GNU license. WebWisdom.com provides this software free of charge.
All sources are available
here.
TANGO Interactive support group
Last modified: Mon Mar 6 14:42:03 EST 2000