Unix Window System

transcript

Unix Window System

October 22nd, 2007

Class Meeting 10

* Notes adapted by Lenwood Heath from previous work by other members of the CS faculty at Virginia Tech

Lenwood Heath, Virginia Tech, Fall, 2004 2

Why Window Systems?

� A window system provides a graphical user interface (GUI) based on windows, icons, and interrupt-driven interaction

� Increased usability due to

� Access to multiple environments and applications at once

� Direct manipulation of graphical objects with mice, joysticks, tablets, etc.

Window Systems and Unix

� Unix evolved before window systems and optimized use of the command line

�Modern Unix systems include a window system to combine the advantages of the window system with the availability of a command line for expert use (that means you!)

X Windows

� Practically all Unix window systems are based on X Windows (XFree86)

� Standard Version: X11R7

� X server:

� Hardware interface (display, mouse, etc.)

� Manages the screen space

� Draws simple graphics

� Assigns rectangular regions to X clients

� Local and remote clients supported

The X Client-Server Architecture

� X designed to work over a network

� X server: software that runs on the machine where the program’s output will be displayed

� X client: program running on the same or another machine

� Client sends drawing and other X commands to the server, which displays the results

Historical Use of X

� User sat at an X terminal – graphical terminal that ran an X server, but no OS

� User logged into remote computer running UNIX or other OS supporting X clients

� Separates graphical interface and manipulation from application

� Combine applications running on multiple computers

Design decisions for X11 (from Wikipedia)

� Do not add new functionality unless you can think of an application that will use it.

� It is as important to decide what a system is not as to decide what it is. Do not serve all the world's needs; rather, make the system extensible so that additional needs can be met in an upwardly compatible fashion.

� The only thing worse than generalizing from one example is generalizing from no examples at all.

� If a problem is not completely understood, it is probably best to provide no solution at all.

� If you can get 90 percent of the desired effect for 10 percent of the work, use the simpler solution.

� Isolate complexity as much as possible.

� Provide mechanism rather than policy. In particular, place user interface policy in the clients' hands.

Window Manager

�Window manager runs on top of X11 and within a desktop manager

� Place borders, sliders, and other widgets on windows to provide the interface look and feel

� Examples: � kwin— default for KDE

� metacity— default for GNOME

� mwm—Motif standalone window manager

Features of X

� Transparent remote execution

� Gives each program its own virtual screen

� Includes important windowing concepts

� Window damage

� Window reveal events

� Backing store

� X11 programs are highly portable

Desktop Environment

� Desktop environment organizes display into an integrated environment

� Includes file managers (Nautilus), icons,

panels, configuration tools, and applets

� GNOME (GNU)

� built on GIMP Toolkit (GTK+)

� KDE (uses Qt C++ libraries)

� XFce (GTK+ based)

XFCE Screenshot

Gnome Screenshot

Advanced desktop features

� Traditional 2D is rather old

� Future: OS X expose / Windows flip

� X11's answer: Compiz / Beryl

Apple Expose

Windows Flip

Compiz Features

M$ vs Unix

� One way for everyone vs choice and flexibility

�Minimalist / Heavyweight

� Interoperability with other software

� Community versus Company vision

X11 on Windows

� Cygwin can turn windows into an X11 terminal

� Start up cygwin and type startx

� You can use commands such as xclock xeyes

� Running programs from rlogin.cs.vt.edu

� Type ssh -X pid@rlogin.cs.vt.edu

� Use xclock or xeyes to verify it works

KDE on XP *shudder*

Windows on X11

� Two methods to get your Windows programs running under X11� Emulation

� WINE

� Virtualization� VMWARE / XEN

� Open source implementation of the windows API

� Can run several windows programs, not everything works

� Commercial variants� Cedega (transgaming.com)

� CrossOver (codeweavers.com)

� Free version: http://www.winehq.org/

Wine screenshot

Virtualization

� Several operating systems on one computer

� Can run windows 2k/xp/vista inside of linux or linux inside of 2k/xp/vista

� Has some overhead / doesn’t allow games (starting to change)

� VMWare (www.vmware.com)

� XEN (www.xensource.com)

Unix Window System

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