X Windows/X protocol

X Window/X protocol: X Window System Protocol for UNIX and Linux graphics display (X Window or X protocol or x System)

X Windows System Protocol, that is, X Windows or X protocol, is a graphical structure used in UNIX and Linux graphics systems. Windows X systems are rarely used in systems such as VMS, MVS and MS-WINDOWS. It provides an inherent Client/Server-oriented basis for displaying window images. X Windows provides a public protocol that allows you to query and update information on X servers. X Windows System (X protocol) allows processes on different computers in the network to display content on other network monitors.

X Windows System (X protocol) defines the following client and server roles:

X Server is a program running on the user's desktop to manage video systems, including interactive I/O devices, such as the mouse, keyboard, and some special devices. Main functions:

1. Display graphical requests on the screen
2. Reply request information
3. Report errors in the request
4. Manage keyboard, mouse, and display devices
5. Repeat the keyboard and mouse input to the network connected to the respective X client (x event ).
6. Create, map, and delete windows
7. Write and draw in Windows

The X client is an application running on another host that connects to the X server to display graphics. A client usually runs on a powerful Unix/Linux platform, that is, a common "server". Main functions:

1. Send request to server
2. Receive events from the server
3. Receive error from server

System x divides various components into separate subsystems. The main components of the X Windows System (X protocol) framework include:

• Windows administrator-controls the occurrence of an event when the mouse pointer points out of the screen controlled by a specific application.
• Programs/file administrators-typically a program that displays application icons and allows users to run these programs.
• Internal Program Interface-x standard mode for client communication, which is called ICCCM. CORBA is also used to provide more sophisticated and complex methods for X-window communication. The implementation of communication is based on the TCP/IP network.

X Windows System (X protocol) includes two basic versions: x10 and X11.

Protocol Structure

The X protocol has the following main communication information between the client and the server:

Request

• The X client sends a service request to the X server, such as creating a window.
• To improve performance, the X client generally does not expect or wait for a response. Requests are retained to a reliable network layer for transmission.
• X requests are any multiple of 4 bytes.

Reply

• X server responds to an X client request. Note: not all requests need to be responded.
• X replies any time of 4 bytes, but the minimum is 32 bytes.

Event

• The X Server forwards the event to the X client. It may include keyboard or mouse input. To reduce network traffic, only the expected events are sent to the X client.
• X events are 32 bytes.

Error

• X Server Reports errors in response to client requests. Errors are similar to events, but they are handled differently.
• X errors are the same size as events, which are used to simplify their processing. They are sent to the X client (32 bytes) error handler.

Related Protocols: IP, TCP, and CORBA

Organization Source: X Window/X protocol was introduced by X. org (http://www.x.org.

Link: http://www.x.org/X11_protocol.html:The X protocol.