Basic X Concepts

The underlying engine of X11 is the X protocol, which provides a system of managing displays on local and remote desktops. The protocol uses a client/server model that allows an abstraction of the drawing of client windows and other decorations locally and over a network. An X server draws client windows, dialog boxes, and buttons that are specific to the local hardware and in response to client requests. The client, however, does not have to be specific to the local hardware. This means that system administrators can set up a network with a large server and clients and enable users to view and use those clients on workstations with totally different CPUs and graphics displays.

Note

What better way to demonstrate the capability of X to handle remote clients than by using its capabilities to produce this chapter. Although the OpenOffice.org file for this chapter resided on a Mac mini (running Xubuntu), the display and keyboard used were actually part of an Acer Ferrari notebook running Ubuntu 6.06, via an ethernet connection. Revisions were done using a Logitech keyboard and mouse of a desktop machine running Kubuntu, again connected to the Mac mini via X, but this time using a wireless connection.

Because X offers users a form of distributed processing, this means that Ubuntu can be used as a very cheap desktop platform for clients that connect to a powerful X server. The more powerful the X server, the larger the number of X-based clients that can be accommodated. This functionality can breathe new life into older hardware, pushing most of the graphical processing on to the server. A fast network is a must if you intend to run many X clients because X can become bandwidth-hungry. X is hugely popular in the UNIX and Linux world for a variety of reasons. The fact that it supports nearly every hardware graphics system is a strong point, as well as strong multiplatform programming standards give it a solid foundation of developers committed to X. Another key benefit of X is its networking capability, which plays a central point in administration of many desktops and can also assist in the deployment of a thin-client computing environment. Being able to launch applications on remote desktops and also standardize installations serve to highlight the versatility of this powerful application.

More recent versions of X have also included support for shaped windows (that is, non-rectangular), graphical login managers (also known as display managers), and compressed fonts. Each release of X brings more features designed to enhance the user experience, including being able to customize how X client applications appear, right down to buttons and windows. Most office and home environments run Linux and X on their local machines. The more enlightened companies and users harness the power of the networking features of X, enabling thin-client environments and allowing the use of customized desktops designed specifically for that company. Having applications launch from a single location makes the lives of system administrators a lot easier because they have to work on only one machine, rather than several.