StudentControlPanelSpec

Revision 6 as of 2006-11-06 18:52:24

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Summary

Roadmap for bringing more functionallity into student-control-panel

Rationale

Student control Panel is an application to control LTSP client conections on a standalone edubuntu server. It was first introduced in edgy on the edubuntu CD and is installed by default in the edubuntu classroom server. The spec for edgy done in paris wasnt completely implemented and additional requirements have come up from the users. this spec describes the advanced needs for the program like working with multiple servers, filter options for the userlist, screen sharing and deep vnc integration as well as removing the edubuntu branding to make it a rather generic LTSP connection control tool.

Use cases

Dr. Miller teaches biology in an LTSP equipped class. He has several students he suspects to secretly browse the web while he is not looking. Using the "Class overview" button in student-control-panel he is able to get a fullscreen view of tiled small VNC windows for the whole class to monitor the students desktops.

Miriam teaches about free software in a class that uses a LTSP setup. She wants to demonstrate several free software apps she wants to start up on all students desktops. She hits Ctrl-a to select all students in student-control-panel and clicks on the execute button which brings up a dialog to execute a command on all selected desktop simultaneously.

Anselmo is school administrator and has several classes that connect to the LTSP server at the same time. He gets a call from the biology teacher who wants all his students to be locked out. To be able to administer only a single class, he uses the predefined filter from the pulldown filter menu in the gui he has set up earlier and manages the task.

Michael has several students who are not listening in his lesson, he presses Ctrl-a to select all students, clicks the lock button from within student-control-panel and the students desktops are all locked with a blank screensaver.

Scope

Easy handling of student LTSP connections on a single LTSP server.

Design and Implementation

WIP below, please do not edit !

  • multiple server control
  • filter functionallity of the userlist
  • forced filter per teacher

  • sharing screen -> exec vnc on the clients desktop connected to your session

  • mini vnc preview in the userlist
  • tiled vnc overview of the complete class on demand

Plugin framework upgrade

  • The current student-control-panel plugin framework allows for server side only plugins. It would be advantageous to provide both server side and client side plugin components. The current framework uses a single class with a register function stored in a python module file. The proposed idea would be to modify the dbus routines to allow information to be passed back from the client to the server. This would then allow much more complex plugins to be created, such as chat programs and initiation of simple file transfers.
  • Many of the new proposed features could then be implemented over this plugin frame work

Assistance Applet

  • Creation of a gnome applet that will act as an assistance helper for users. They will be able to click and ask for assistance. Possibly also used to drag and drop answers for a teachers specified question.

Blank / Lock Workstations

  • A system for locking keyboards and mice, as well as blanking a workstation would be a good idea. This could simply be achieved by starting the xscreensaver program on the clients machine but running as a different user. This would allow the password to be unknown to the client and the process could then be killed automatically by the server on removing the blank/lock restriction.

Generalisation of SCP

  • It has been recognised that SCP has applications outside of the school/education setting. It is proposed to rename the package and give it a more generic feel.

Remote desktop access

  • Student Control Panel will use vnc for remote desktop access. A function using the vncclient package is already completely implemented in the current student control panel code but disabled in the GUI since the handling on the LTSP client side wasn't clear yet; we will now fix that by adding a vnc server application (x11vnc) to the LTSP client chroot.
  • For the client implementation the x11vnc package will have to be installed in the client chroot.
    • The package will get a preseedable debconf option (suggestion: ltsp-client-mode), if this option is set to true, the postinst script installs an initscript which starts x11vnc connected to localhost:0 at boottime of the client and makes it read a custom password from a file thats located in the client chroot.
    • Student Control Panel will generate this password dynamically on every startup of the Student control Panel GUI (using PASSWORD=$(pwgen -c -n -s 20 1) should suffice here) and rewrite the password in the file. Since x11vnc reads the password on every new connection from that file it *could* affect existing Student Control Panel sessions. Because of this Student Control Panel will not start if there is already a running instance but spill a warning to first close the old one.
  • Since we dont want to run apt-get install from Student Control Panels postinst script in the LTSP client chroot, we can't just install x11vnc at install time of the student-control-panel package.
    • A "first start popup window" will be added to the GUI, with a checkbox "Dont show this window again" and a button "Install remote desktop access".

    • Choosing the latter option will execute a script /usr/share/student-control-panel/install-client-vnc.sh which will run  apt-get install x11vnc  in the LTSP client chroot with the above described option preseeded.

Outstanding issues

  • Determine the best default options (compression, scaling of the windowsize etc) for x11vnc to be added to the initscript by user feedback during developent.

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