Transcript UNIX - SigmaNet

Unix GUI
Guntis Barzdins
Girts Folkmanis
Exception: MacOS X uses a proprietary Aqua
windowing system (more efficient than X11)
Classic X11
[Guntis-Computer:/usr/X11R6/bin] guntis% ls
X
luit
xbiff
Xmark
makedepend
xcalc
Xnest
makeg
xclipboard
Xprt
makepsres
xclock
Xquartz
makestrs
xcmsdb
Xvfb
mergelib
xconsole
appres
mkcfm
xcursor-config
atobm
mkdirhier
xcutsel
bdftopcf
mkfontdir
xditview
bdftruncate
mkfontscale
xdm
beforelight
mkhtmlindex
xdpyinfo
bitmap
oclock
xedit
bmtoa
proxymngr
xev
ccmakedep
pswrap
xeyes
cleanlinks
quartz-wm
xfd
cxpm
resize
xfindproxy
dpsexec
revpath
xfontsel
dpsinfo
rman
xfs
dumpkeymap
rstart
xfsinfo
editres
rstartd
xft-config
fc-cache
sessreg
xfwp
fc-list
setxkbmap
xgamma
fontconfig-config
showfont
xgc
freetype-config
showrgb
xhost
fslsfonts
smproxy
xinit
fstobdf
startx
xkbbell
gccmakedep
sxpm
xkbcomp
glxgears
texteroids
xkbevd
glxinfo
twm
xkbprint
iceauth
ucs2any
xkbvleds
ico
uxterm
xkbwatch
imake
viewres
xkill
lbxproxy
x11perf
xload
listres
x11perfcomp
xlogo
lndir
xauth
xlsatoms
[Guntis-Computer:/usr/X11R6/bin] guntis% man xwud
xlsclients
xlsfonts
xmag
xman
xmessage
xmh
xmkmf
xmodmap
xon
xprop
xrandr
xrdb
xrefresh
xset
xsetmode
xsetpointer
xsetroot
xsm
xstdcmap
xterm
xtrapchar
xtrapin
xtrapinfo
xtrapout
xtrapproto
xtrapreset
xtrapstats
xvidtune
xvinfo
xwd
xwininfo
xwud
Topics
 X Windows
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X Protocol
Classic X apps
Starting X apps
Window managers
Desktop environments
Desktop applications
X Window
 The X Window system was developed as part of
Project Athena at MIT. In 1987, X Version 11 is
released. X is now controlled and maintained by the
Open Group.
 The X Windows System, also referred to as ‘X’ or
“X11”, is the standard graphical engine for Unix and
Linux.
 It is largely OS and hardware independent, it is
network-transparent, and it supports many different
desktops.
The Graphic User Interface in X
 X Window uses a bit-mapped display where each pixel
can be manipulated individually.
 The entire display is known as the root window, and
individual applications are displayed as windows on this
root window.
 X is started with the startx or xinit commands.

X can also be invoked during system startup
X Protocol
The X Protocol provides a client-server architecture at
the application level:
The X client is the processing part of the application
and often runs on a remote machine.
The X server is the display and interaction system.
X Protocol cont’d
The X Protocol is also divided into device dependent and
device independent layers.
X Server Design
 Device Dependent Layer
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It is this layer that is responsible for localizing the X server to
the native environment, be it Windows NT or Solaris.
This layer swaps bytes of data from machines with differing
byte ordering. Byte ordering (MSB and LSB) is noted in each X
request.
This layer hides the architectural differences in hardware and
operating systems.
Maintains device driver dependencies for keyboard, mouse and
video.
Networked Windowing
 X Window designed to allow apps to run on
remote machines
 Uses client-server model
X Server
std system software
User
Network
Client
app software
X architecture
The client-server nature of the X Protocol allows a single X
server to support many clients (applications) on several hosts.
Client-Server Window System
Client Application
Programs
Application 1
Application 2
Application n
Virtual
display 1
Virtual
display 2
Virtual
display n
Server
Could be
Window
Manager
Resource
allocator
Device-independent abstraction level
Translates abstraction into reality:
one per terminal type
Devices
Keyboard Mouse
Device
driver
Window
1
Window
2
Window
n
(After Fig 10.2, Dix, Finlay,
Abowd and Beale)
X Protocol messages
Requests – client sends requests to the server (e.g. create window)
Replies – server response to client requests
Events – server forwards events (such as mouse clicks or keyboard
entry) to the client
Errors – server reports errors to the client
X Server
The X server therefore:
 displays drawing requests on the screen.
 replies to information requests.
 reports an error in a request.
 Manages the keyboard, mouse and display device.

Multiplexes keyboard and mouse input onto the network (or via
local IPC) to the respective X clients. (X events)
 creates, maps and destroys windows.

writes and draws in windows
X Client
 sends requests to the server.
 receives events from server.
 receives errors from the server
Protocol Messages
Requests
 X clients make requests to the X server for a
certain action to take place. i.e.: Create Window
 To enhance performance, the X client normally
does not expect nor wait for a response. The
request is typically left to the reliable network
layer to deliver.
Protocol Messages
Replies
 The X server will respond to certain X client
requests that require a reply. As noted, not all
requests require a reply.
Protocol Messages
Events
 The X server will forward to the X client an event
that the application is expecting. This could
include keyboard or mouse input. To minimize
network traffic, only expected events are sent to X
clients.
 X events are 32 bytes
Protocol Messages
Errors
 The X server will report errors in requests to the X
client. Errors are like an event but are handled
differently.
 X errors are the same size as events to simplify
their handling. They are sent to the error handling
routine of the X client.
X Windows Protocol Overview
X Windows is the predominate windowing system on UNIX computers, developed by the X Consortium, lead by M.I.T. An X server manages
the display on the workstation. Clients can connect to server via TCP/IP and perform graphics operations. This makes X Windows much
more network capable than Microsoft Windows, for example, which can only be accessed via a local API.
X Windows operates over TCP, typically using server port numbers starting with 6000. The X server for a system's first display listens on
port 6000; if the system has a second display, its server listens on port 6001; a third display would listen on 6002; etc. The protocol used
over this reliable stream connection is essentially request/reply, and it's reputation is as a fat protocol that consumes a lot of bandwidth.
Lightweight X (LWX), introduced in X11R6, attempts to reduces X's bandwidth needs to the point where it can be run over dialup modem
connections.
The X Protocol, documented in a postscript file, defines dozens of messages that can be exchanged between a client and a server. They
can generally be classified into four categories: Requests, Replies, Events, and Errors. Typical requests include Draw PolyLine, Draw Text,
Create Window, Fill. Replies are matched to particular Requests. Events are asynchronous occurances such as keystrokes and mouse
clicks. Errors are matched to particular Requests.
If a window is partially or fully obscured by another, overlapping window, the server has two options available to it. The server can allocate
additional memory, called backing store, to record to contents of the obscured window. This is purely optional, however. The server can
simply ignore the obscured part of the window. Later, when that part of the window becomes visible again, the server sends an Expose
event to the client, which must then redraw the affected area. The client, therefore, must be prepared to redraw any part of its windows at
any time.
Applications do not need to access the X Windows protocol directly. X Windows supports several APIs. The most basic of these is Xlib,
which interfaces fairly directly to the underlying network protocol. Most X client applications are linked against Xlib, which allows them to
operate on either a local or remote X server, simply by adjusting either an environment variable or a command-line argument.
Widgets layer on top of Xlib and provide X Windows with an object-oriented programming model. A widget is an X window capable of
handling most of its own protocol interaction. The most popular widget sets are Athena Widgets (aw) and Motif.
X Window's security model is all-or-nothing. Either an application can perform any operation on an X desktop, or it can perform none. There
is no concept of limiting an application to a single top-level window, for example. Although there is power in this model, such as allowing the
window manager to be a normal X client, there are also serious performance implications. A hostile X client could connect to an X server
and arrange to capture any screen image, or even to capture keystrokes as a password is being typing in one of the windows. For this
reasons, X servers are typically fairly restrictive about which clients they will accept connections from. Two major security models are
available. Host-based security (traditionally controlled by the xhost program), permits or denies connections based on their source IP
addresses. Authentication (traditionally controlled by the xauth program), requires the connecting program to possess a secret password ,
typically stored in a UNIX file and subject to standard UNIX access controls. Kerberos-based authentication is also available.
Starting X Windows
On a local PC or workstation, you can usually start the
X server with the “xinit” (“startx”) command or it may
be started automatically by “xdm” (graphical login
display).
Configuration stored in /etc/XF86Config
Usually edited with utility /usr/X11R6/bin/xf86config
or /usr/X11R6/bin/xf86cfg
xf86cfg
Configuring X Windows
 mouseconfig

Command used to configure a mouse for use by X
Windows
 xconfigurator
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A program that is used to configure video adapter
card and monitor information for use by X Windows
redhat-config-xfree86 used in recent
Red Hat & in Fedora
Configuring X Windows
 Fedora and X Windows configuration
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
Fedora has greatly improved video & monitor
detection
Not included in Fedora (Red Hat only):
SuperProbe
 Xf86config
 Xconfigurator

Starting X applications
To launch an X client from a remote host for display on the
local X server, you need to set two things:
1) Permission for the remote host to display X clients on the
local machine.
xhost +remotehost
2) The target display for the remote application.
setenv DISPLAY=server:display
[hostname]:displaynumber[.screennumber]
not needed,
if same host
“0” in most cases
defaults to “0”
/etc/X11/xinit/xinitrc (xinit)
or /home/g/.xsession (xdm)
#!/bin/sh
# $Id: xinitrc,v 1.2 2003/02/27 19:03:30 jharper Exp $
xrdb -load $HOME/.Xresources
xsetroot -solid gray &
xclock -g 50x50-0+0 -bw 0 &
xterm &
loads resources: default fonts,
colours, window sizes
# start the window manager
exec twm
xinit exceutes this script
last line: replaces shell-script with window
manager, will terminate all background
processes on exit
Window managers
One can use X11 without a window manager.

Typically, one writes a session script which starts an "xterm" at a "-geometry" location.
One then starts other X11 clients by giving their "-geometry" explicitly, because there is
no window manager
The window manager is a special X client that controls the placement and movement
of applications, provides title bars and control buttons, menus and taskbars. Some
support virtual desktops and very fancy graphics.

When a window manager is running, some of interaction between the X server and its
clients is redirected through the window manager.
Classic window managers include:

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TWM
MWM - Motif Window Manager
Nowadays, KDE (kwm) and GNOME (sawfish) are two widely used window managers
in Linux.
The Tab Window Manager (TWM)
xterm
The most important X application is, rather ironically, the
terminal program xterm.
Old school xterm:
xterm: The Main Client
 You can invoke all UNIX commands and X programs form the
UNIX command line available in an xterm window.
 xterm can also be used with a scrollbar
(-sb), and the number of lines saved can be specified (-sl).
 You can position and specify the size and position of a window (geometry) and its foreground and background color
(-fg and -bg).
 You can start a program as an icon (-icon) and provide a name (name) or title (-title).
Some classic X apps
xclock – pretty self-explanatory
Some classic X apps
xeyes – ok, this is really the most important
xnest
XFree86
“In short, XFree86 is an open source X11-based
desktop infrastructure.” – xfree86.org
X.org Foundation – sucessor of XFree86
Used in most Linux distributions
Window managers,
Widget toolkits,
Desktop environments,
Desktop applications
X and the GUI
 X itself provides the back end needed
for a GUI. It doesn’t, however, provide
an interface itself.
 Window management functions – e.g.
moving or resizing windows – are
performed by a window manager,
which is itself an X client. These range
from the spartan (twm) to the complex
and graphically intensive
(Enlightenment).
 There are various different toolkits for
creating graphical applications,
providing libraries of widgets such as
buttons etc. These range from the old
and ugly (Motif) to the new and shiny
(GTK+, Qt)
 No two users can be assumed to have
the same window manager and
different applications can use different
toolkits (or even write their own).
Therefore, there’s a lack of consistency
about the average X desktop – this
makes things ugly and can be hard to
use.
Why not only a basic X11
environment?
 Most X11 applications have important shortcomings:
 Application Interoperability is too hard
 User Interface is inconsistent and of unequal quality
 Modern desktop environment brings the "glue"
 Drag & Drop, Session Management, etc...
 Consistent "look and feel"
 Unified Help System
 Easy dialog based desktop configuration
 Common application development framework (-> MFC)
 Compound document framework (-> OLE)
 New exciting possibilities:
 Hundreds of new applications (including Office)
 Powerful application development environment
Linux GUI Components
Graphical Programs (X clients)
Desktop Environment
Window Manager
X Windows
Video Adapter Card Hardware
Motif Window manager
and Widgets
KDE
 KDE is the traditional desktop environment
used on Linux systems
 K Windows Manager (kwm)

The window manager that works under the KDE
Desktop Environment
 Qt toolkit

Software toolkit used with the KDE Desktop
environment
Linux Developement
 Qt Class Library
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C++
Cross Platform
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Qt/Windows
Qt/X11 (Linux, Solaris, HPUX,
AIX, etc)
Qt/Mac
GPL – Free for non-commercial apps
Qt was used to build KDE
from Trolltech in Norway
www.trolltech.com
Gnome
 GNOME Desktop Environment


Default desktop environment in Red Hat Linux
Typically uses the Sawfish Window Manager and
the GTK+ toolkit for the C programming language

The GTK+ toolkit was originally developed for the
GNU Image Manipulation Program (GIMP)
 Ported also to MS Win, MacOS X planned
Bluecurve
 Bluecurve
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Both a visual theme and a set of modifications to
the KDE and GNOME environments
Gives both a common “look & feel”
Smooths out inconsistent behaviors between the
different WMs
The KDE Desktop Environment
The Bluecurve + KDE in Fedora
The GNOME Desktop Environment
The Bluecurve + GNOME in Fedora
KDE and Gnome architectures
What is a desktop?
 It is the top of a desk
 It is a pc cabinet for the
desktop
 It is the graphical user
interface (GUI) on a pc
 It is the graphical enviroment
for the average user on a pc
KDE and GNOME
 K Desktop Environment
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
KDE is a "complete desktop environment that try to
make linux accessible to everybody"
At present KDE 3.5
 GNU Network Object Model Environment


AIM: "GNOME Intends to build a complete, userfriendly desktop, similar to CDE or KDE, but based
entirely on free software"
At present GNOME 2.14
KDE
http://www.kde.org/
KDE
GNOME
http://www.gnome.org/
Render Extension Shadows
Render Extension Translucency
Render Extension –
anti-alias font
SuperKaramba dynamic background info
More GUI on Linux
 X Window server
 Window Managers
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KDE
GNOME
WindowMaker
FVWM
Enlightenment
IceWM
CorelLinux
WindowMaker
http://www.windowmaker.org/
FVWM
http://www.fvwm.org/
Enlightment
http://www.enlightenment.org/
IceWM
http://iceorg.sourceforge.net/
Corel Linux
http://linux.corel.com/
Office suites for Linux
 WordPerfect Office
 ApplixWare
 StarOffice
 GNOME Office
 KOffice
WordPerfect Officesuite
 Corel
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WordPerfect
QuattroPro
Presentation
Paradox
(CorelDRAW)
 Danish September
 Proprietary
 ~ 2.000 Dkr
Sorry
no screenshot
available
Applixware
 Applix
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Words
Spreadsheets
Presents
Graphics
Data
 Danish spellchecker
 Proprietary
 ~ 800 Dkr
StarOffice / OpenOffice
 SUN Microsystems
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Writer
Calc
Impress
Draw
Base
 Danish in june
 Free, not Open Source
KOffice
 KDE project
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KWord
KSpread
Kpresenter
Killustrator
KChart
 Open Source
GNOME Office
 GNOME project
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AbiWord
Gnumeric
GIMP
Dia
GNOME-DB
 Open Source
Other desktop applications
 GIMP
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Image editor á la Adobe
Photoshop
Free and open
Thousands of plug-ins
 Mozilla
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Webbrowser (Firefox)
Mailclient (Thunderbird)
Office Suites
SpreadSheet
Presentation
Vector Drawing
Word Processor
Chart Drawing
Formula Editor
Image Processor
Diagram Creation
Planning Events
Calendar
StarOffice
KDE
GNOME
MS Windows
StarCalc
StarImpress
StarDraw
StarWriter
StarChart
StarMath
StarImage
Kspread
Kpresenter
Killustrator
Kword
Kdiagramm
Kformula
Kimage
Gnumeric
Achtung
Gill
AbiWord
Guppi
Excel
PowerPoint
Paint
Word
Excel Graphic Feature
Equation Editor
Ms. Image
Visio
Gimp
Dia
StarSchedule
Korganizer Gcalendar
Using X windows remotely on
a MS-Windows machine.
 You need to get a program called an “Xserver”.
Exceed works well and is free for academic use.
Cygwin is another option.
 You must allow X-forwarding through your ssh
client. Putty is good for this.
X server security configuration
xhost
xhost simply allows you to specify which machines are, or aren't allowed to connect to the X server, this is a very
simplistic security mechanism and is not really suitable in any modern environment, however used in conjunction
with other mechanisms it can help. The command is quite simple: 'xhost +example.org' adds example.org, 'xhost example.org' removes example.org from the list, you must also specify 'xhost -' to turn on the access control list, or
else everyone is let in by default.
mkxauth
mkxauth is definitely a step up from xhost. mkxauth helps create ~/.Xauthority files, and merge them, which are used
to specify hostnames and the related magic cookies (basically a token used to gain access). These cookies can then
be used to gain access to a remote X host (you essentially have a copy of the cookie on each end) and are
transferred either plain text (insecure) or DES encrypted (quite secure). Using this method you can be relatively safe
and secure. Xauthority files can also be used in conjunction with Kerberos, removing the necessity to copy
Xauthority files around and keep them in synchronization. Hosts authenticate to each other through a central
Kerberos key server(s) in an encrypted fashion, this method is most appropriate for large installations/etc. mkxauth
has an excellent man page 'man mkxauth' and more generalized details are available in the Xsecurity man page (not
sure how common this name page is) 'man Xsecurity'.
SSH tunnel
SSH or OpenSSH can be used to create a tunnel between hosts (or more specifically between two X servers), thus
encrypting the channel, providing authentication, and generally making things safer. The following web page explains
it http://csociety.ecn.purdue.edu/~sigos/projects/ssh/forwarding/.
Mac OS X
Mac OS X Architecture
Apple’s Boiled Sweets diagram
http://developer.apple.com/macosx/architecture/