Features/SystemWideDesktopNotification

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System Wide Desktop Notification

Summary

Currently there is no standard way for system (or LAN) wide messages to be delivered to users in a desktop environment. The traditional utilities "wall" and "rwall" only work for users who have open shell windows. While there are a variety of ways of delivering desktop notifications, none of these are convenient for system level notification.

Owner

  • Name: Ian Dall


Current status

  • Targeted release: Fedora 21
  • Last updated: 12 Dec 2009
  • Percentage of completion: 00%


Detailed Description

The traditional "wall" works by trawling through utmp and finding the tty's of logged in users, then writing a message to that tty. The same mechanism is apparently used by "shutdown" and "syslog". There needs to be a way for shutdown, syslog and admin scripts to send a message which is almost guaranteed to be seen by all logged in users.

Benefit to Fedora

Currently "wall" is effectively broken in all unix based systems due to the paradigm shift from terminal interaction to graphical desktops. Programs such as "shutdown" send messages which are expected to be seen by all logged in users, but are not. This deficiency has been hidden to some extent by the common practice of having leaving terminal windows open. However as this becomes less common, the impact of the deficiency becomes greater. This feature will allow users of graphical desktops to see critical messages which they might currently miss. The need to deliver this messages is especially relevant in multi-user or enterprise environments, which might include multiple users on graphical desktops via thin clients.

Scope

Many of the elements exist. There are several ways of actually displaying a message on the desktop, but xfce4-notifyd works pretty well and is used for desktop notifications within a session.

Currently xfce4-notifyd only listens to the d-bus session bus. If it listened to the d-bus system bus as well, and libnotify were modified to optionally use the system bus then the feature would mostly be implemented. Additionally the "notify-send" utility would need an option to use the system bus. The "shutdown" utility and the "rsyslog" daemon would need to be modified to send notifications on the system bus as well. Possibly "wall" should be modified as well so that scripts which already use wall can reach graphical desktop users without change.

How To Test

  1. Log in to a default fedora desktop
  2. Ensure /etc/rsyslog.conf has the line *.emerg *
  3. Enter logger -p emerg "Just Testing"
  4. Observe graphical notification message
  5. Enter shutdown -k now "Just Testing"; shutdown -c
  6. Observe graphical notification message
  7. Enter notify-send --system "Just Testing"
  8. Observe graphical notification message
  9. Enter wall "Just Testing"
  10. Observe graphical notification message

User Experience

Users will, when critical system events happen, see an alpha blended message box, which fades as it times out.

Dependencies

This would not be a new package but would requires coordinated changes across several packages. With the proposed implementation, these would be: xfce4-notifyd, rsyslog, upstart, libnotify and sysvinit-tools.

Contingency Plan

These changes should be able to be introduced without disrupting existing behaviour. In the event that a change does disrupt exiting behaviour, revert the change.

Also the changes can be phased. For example: change xfce-notifyd and libnotify first, then change rsyslog, shutdown etc.

Documentation

Release Notes

Comments and Discussion