Introduction to
NX technology

A brief introduction to NX motivation and technology

NX Distributed Computing Architecture is a suite of Open Source technologies and commercial tools, designed to make network computing as easy and widespread as browsing the web. It consists of a thin layer of server software that enables any Unix computer to work as a terminal server. Clients are also available for a wide range of platforms and operating systems. NoMachine has chosen to build the foundations of its NX Distributed Computing Architecture on the well known and widely used X-Window System - the windowing system that's behind the Graphical User Interfaces of Linux and the Unix Operating System.

Most network computing solutions seem to be designed to work as surrogate tools. It appears that the architects behind their design did not intend them to be the primary means by which users access their desktops. This is the problem, for example, with VNC and RDP. Both these protocols are much simpler than X (and so very well suited for thin clients), but their simplicity does not compensate for their lack of efficiency and functions. These protocols, for example, draw the remote screen by transferring huge amounts of image data over the network. Even if RDP is of a much higher level and a much more efficient protocol than RFB, it has not been designed for everyday use of computing resources, but as an add-on to the underlying operating system.

X-Window is the graphical subsystem ,and not an extension, of the host OS’s subsystem. X applications communicate with X-Window using the X protocol, so that the operating system does not have to add a layer to translate screen updates into a network protocol.

X-Window System is an open and extensible client-server protocol, designed to offer a layer of separation between the application logic (running on application servers) and the presentation (taking place at clients). In other words it has been designed for network computing. The native X protocol requires high bandwidth and low latency networks to work at its best. Over the years, though, evolution of Graphical User Interfaces has increased the demand for network and computing resources. Instead of layering X applications to adapt to available network resources, X client and X toolkit designers have relied on users giving up X-Window's networking capabilities to simply access applications running on their own computers. Over the last few years, the X-Window system has completely lost its original characteristics of network computing protocol, being perceived as a mere display driver even by the most informed and technological users.

The main goal of the NX project, since the beginning, has been to develop X compression technology that would enable any user to run unmodified versions of the most widespread X desktop environments on a standard X server, over any type of network connection. This is, according to us, what is first needed to allow X-Window system regain its function of networking protocol.

NoMachine has developed exclusive X protocol compression techniques and an integrated set of proxy agents that make it possible to run complete remote desktop sessions, even at full screen, using narrowband Internet connections, at speeds as low as those offered by a 9600 band modem.

NX compression operates at three levels on the X protocol:

• It compresses the network traffic by a variety of means, including -per message- differential algorithms, advanced caching methods, lossless and lossy image compression.
• It reduces network round-trips nearly to zero, maximizing the throughput.
• Adapts bandwidth in real-time, according to the network conditions.

NX provides X protocol compression ratios ranging from 10:1 to 100:1 and over, depending on the application being displayed. This is obtained without penalizing performances on fast LANs, so that remote sessions can usually run at a speed that is indistinguishable by a local computer.

NoMachine has released as Open Source all the core libraries and low level software components developed to support its NX Distributed Computing Architecture. This includes the X agents, the client proxy and all the libraries implementing compressed transport of X protocol. NoMachine has chosen the GNU General Public License, the same license that drives the development of the Linux operating system. NoMachine aims to support a wide community of developers, working together to create interactive server and client software to make the Network Computing revolution possible.

Whilst being an established platform in the server operating system market, Linux is also emerging as a reality on the desktop. Desktop environments like KDE and GNOME, and the StarOffice award winning office productivity suite, use the X-Window protocol. NX support of such environments comes at zero cost and provides the best performances overall.

Although NX compression offers the best performances when running native X applications, RDP and RFB sessions can be compressed by a factor ranging from 2 to 10. NX support of foreign protocols provides further advantages. Firstly, it extends its reach to virtually any computer and secondly, NX offers to the user a unified view of any application resource available over the Internet.

NX Nodes are not intended to be dedicated computers (even if this is likely to be a common scenario in legacy contexts). Any computer on any desktop can be a node of a NX Distributed Network. An NX network is very similar to a peer-to-peer network where clients search for a song (in this case a single application or a desktop environment) and the search engine redirects the client to the appropriate server, providing, on behalf of the client, the authorization credential that will have to be submitted to let the node accept the connection.

When a user chooses to run applications inside the existing X session, windows are "floating" on the desktop and integrate perfectly with local applications. In this case, NX operates as a transparent proxy, compressing X traffic and tunnelling the add-on network services (like multimedia and SMB protocol) but without offering local resolution of X protocol's round-trips, made possible by NX agent.