x-window

了解x window 架構及過程

更新記錄

item	note
20160712	第一版
20170222	增加x-windows

X Windows由三個部分組成
- X Server：主控台
- X Client: 應用軟体
- Window Manager：視窗管理軟体
GNOME及KDE為Desktop Manager
X Server
- 1個Linux中可以同時存在好幾個X Server
- 因此，要先給所執行的X Server 一個編號，像「X：2」
- X啟動時，預設的編號會從0開始計算(並以第7個console,也就是Ctrl+Alt+7)產生第一個X Server
X Client
- X Client就有非常多的軟體可以使用，最簡單的就是xterm
- xterm –display:0，就可以將該xterm軟體在編號為0的X Server上執行

由於X只是工具套件及架構規範，本身並無實際參與運作的實體，所以必須有人依據此標準進行開發撰寫

item	description
1984	麻省理工學院 (MIT) 與 DEC(Digital Equipment Corporation) 進行 Athena 計劃發展 X Window System (根據史丹佛大學的 W 視窗系統為基礎)；同年間，第一個版本 X1 發行
1987	X.Org所用的協定版本，X11，是在1987年9月所發佈
1995	X協會公司接手了UNIX系统的Motif工具箱和CDE（Common Desktop Environment）共通桌面環境。而原有的X協會在发布了最后一个版本的X11R6.3后，于1996年末解散
2004	最常见的X变体是XFree86 (它源于X的386兼容的PC机的移植)
2012	X.Org基金会所領導 , 最新的參考實作（參考性、示範性的實作體）版本則是X11 Release 7.7（簡稱：X11R7.7）

X Window 源於1984年的麻省理工學院（目前所發佈的 X11 發表於1987年9月）

來源:X Window System core protocol
The X Window System core protocol is the base protocol of the X Window System, which is a networked windowing system for bitmap displays used to build graphical user interfaces on Unix, Unix-like, and other operating systems.
X Window System
- client–server model
- a single server controls the input/output hardware, such as the screen, the keyboard, and the mouse
- all application programs act as clients
only four kinds of packets are sent, asynchronously, over the network: requests, replies, events, and errors

item	description
X server	X.Org Server , Cygwin/X , XFree86
client 可使用的library	Xlib , XCB
X 顯示管理器	顯示管理器在本機電腦上執行一個或多個 X 伺服器，並接受來自遠端電腦上執行的 X 伺服器的新連線
	1- GNOME显示管理器 (GNOME Display Manager，GDM)
	2- KDE 顯示管理器 (KDM)
	3- LightDM 顯示管理器 (LightDM)
	4- XDM 是 X Window 系統所提供最基本的顯示管理器
	5- twm (Tab Window Manager)
使用者界面元件	1- Motif (CDE)
	2- GTK+ (用於GNOME)
	3- QT (用於KDE)

Xlib appeared around 1985
The XCB library is an attempt to replace Xlib
Xlib (also known as libX11) is an X Window System protocol client library written in the C programming language
Xlib functions to provide widget toolkits
- X Toolkit intrinsics (Xt)
- Athena widget set (Xaw)
- Motif
- FLTK
- GTK+
- QT(X11 version)
- SDL (Simple DirectMedia Layer)
Xlib does not provide support for buttons, menus, scrollbars, etc. Such widgets are provided by other libraries , which in turn use Xlib
- libraries built atop of the X Toolkit Intrinsics library (Xt), which provides support for widgets
- libraries that provide widget sets using Xlib directly, without the Xt library, such as the X versions of GTK+, Qt, FLTK and fpGUI.

XCB (X protocol C-language Binding) is a library implementing the client-side of the X11 display server protocol
The project was started in 2001 by Bart Massey and aims to replace Xlib
The main goals of XCB are to
- Reduce library size and complexity
- Provide direct access to the X11 protocol

item	description
display server	1- libxserver : x.org, Xfree86, X-win32
	2- libwayland-server: Wayland Compositor
system daemons:	1- systemd
	2- D-Bus-Daemon
User Interface Toolkits	libwaylan-client: GTK+ , QT, SDL