XWN740

1
XWN740

• X-Windows
• Configuring and Using
• Session / Window Managers
• Desktop Environments
• (Chapter 8 Pages 118-132)?

2
Agenda

• Session / Window Managers
• Desktop Environments
• Session Managers
• Virtual Desktops
• Desktop Environments
• Window Managers
• Running Windows Manager Alone

3
X Windows Layers

• X Windows comes in layers. Some layers are
  required - some are optional...
• A DISPLAY MANAGER allows selection of user
  (possibly type of Desktop Environment) and to
  provide authentication
• Some Display Managers are started in /etc/inittab
  file, others are started by startup scripts

4
X Windows Layers

• We will now focus on the remaining 3
  levelsSession ManagerWindow ManagerDesktop
  Environment
• We can mix and match these layers to provide the
  clients / employer with a customized graphical
  environment.

5
Session Managers

• A session manager (SM) is responsible for saving
  and restoring the session state this allows the
  user to log out and later log in, and to
  findmore or lessthe same programs running.
• The state information can include the window
  position, open files, cursor position, and so
  forth.
• If the session manager finds that no previous
  session has been saved, a default session can be
  started.

6
Session Managers

• A protocol named X Session Management Protocol
  (XSMP) specifies how applications and session
  managers interact.
• Of particular importance is that the window
  manager is able to communicate with the session
  manager, as the window manager is responsible for
  the placement of windows and the existence of
  icons.

7
Session Managers

• At the beginning of a session, the SM starts
  clients that have a saved state. To enable
  communication with the session manager, clients
  are passed a connection string in the
  SESSION_MANAGER environment variable.
• This takes one of two forms
• tcp/hostnameport
• local/hostnamepath

8
Session Managers

• When an XSMP-aware client starts, it connects to
  the SM and introduces itself. The SM assigns a
  unique ID number, and the client informs the SM
  of the command line that will start it with the
  same ID number.
• It's also possible for clients to ask to be
  restarted if they terminate unexpectedly, or to
  save their state and ask to be restarted in the
  next session even if they are not running at the
  end of the current session.

9
Session Managers

• KDE and GNOME each provide session managers.
• The standard X distribution also provides a
  session manager, known as xsm, but it is NOT
  commonly used...

10
Window Manager
msaul linux gt

• A Window Manager manages window placement and
  provides window decorations. This includes window
  title bars, borders, and controls for common
  operations such as resizing, maximizing,
  minimizing, moving, and closing windows.
• There are different window Managers available to
  the X Windows system that provide flexibility in
  terms of function versus system performance(also
  referred to as overhead).

11
Window Manager

• Examples of Window Managers include
• Metacity (Motif) Window Manager (mwm)?
• Enlightenment (enlightenment)?
• Tab Window Manager (twm)?
• Virtual Tab Window Manager (vtwm)?
• Window Maker (wmaker)?
• Ice Window Manager (icewm)?

Note Each window manager has its own set of
rules and format for window decorations...
12
Virtual Desktops

• Many of the current window managers
  providevirtual desktop or workspace
  capabilitythe ability to access a desktop space
  that is a multiple of the screen size.
• For example, a window manager configured with
  four virtual desktops would permit you to move
  with the mouse or keyboard from one of the four
  desktops to another.
• Windows managed on multiple virtual desktops do
  not take significantly more resources than
  windows managed on a single desktop

13
Virtual Desktops

• There are two different ways to create virtual
  desktops
• Mapping
• Windows are mapped (made visible) or unmapped
  (hidden) according to whether the desktop they
  are "on" is the current desktop.
• Positioning
• Windows are positioned relative to the current
  desktop if they are on a desktop to the right of
  the current desktop, then they are positioned to
  the right of the visible screen area, off the
  screen.

14
Virtual Desktops

• When the virtual desktop illusion is created by
  window positions, it is possible to have the
  current desktop positioned between virtual
  desktops, so that parts of two or more virtual
  desktops are visible simultaneously.
• It's also possible to have windowsspan virtual
  desktops.

15
Desktop Environments

• As mentioned in previous lessons, the role of the
  Desktop environment is to provide the user with
  additional features while running an X Windows
  session.
• There features that may include menus to start
  programs, trays or panels to indicate currently
  running programs, icons that represent files or
  programs on the desktop background, docked
  applets, and other useful tools and utilities.

16
Desktop Environments

• There are many Desktop environments that are
  available for download and installation
  including
• Gnome
• KDE
• Xfce
• Workbench
• Enlightenment
• Windowmaker

Most commonly used...
There is sometimes confusion between a window
manager and a desktop environment. Some desktop
environments consist of a window manager, or
bundle a suite of programs including the window
manager...
17
Starting SM, WM, DE

• By now, you should realize that rules for
  starting DM, SM, WM, DE (Desktop Environment) are
  started from a configuration file and/or a script
  file.
• The location of these files usually depends on
  the Linux distribution you are currently using,
  and the type of Desktop / Window Manager that is
  installed...
• Refer to X Power Tools Chapter 8 sections 8.4,
  8.5, and 8.6 for examples involving Gnome, KDE,
  Xfce

18
Window Manger Only

• Useful for keeping overhead down for performance
  (for example a KIOSK)
• A script can be used to specify the type of MW
  and which clients to then start.
• Refer to X Power Tools Chapter 8 section 8.7 for
  and example of creating a customized shells
  script and running startx with this script...