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Autumn 2001
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Axel Technologies believe there must be a significant difference in pricing between a thin-client terminal and a PC. Also thin-clients must have the robust qualities terminal users have come to expect whilst still being able to run Windows and Unix applications.
The Ax3000 does not have an embedded operating system, nor does it swamp the network by booting a remote operating system. On power-up the Ax3000 immediately runs an embedded telnet client and connects onto the server over ethernet LAN/WAN. (Windows connectivity is covered later)
There are many advantages in not running a local operating system and running
the application on the server. There is no requirement for local memory, CPU,
or the operating system itself, reducing administration overhead and cost. As
all software is held on the server, upgrades and backing up are centralised
and simple
By comparison traditional ‘fat’ thin-clients often have an embedded
Windows derived operating system which requires significant hardware resources
even before any ‘useful’ application is run.
Axel’s approach has been to take the proven character based terminal and increase its functionality, as opposed to taking a low cost PC and removing the CD-Rom and floppy drives and claiming it to be something new. We believe that a thin client should be more than a dumbed down PC.
There is no technical reason why a terminal should require an operating system. Indeed this is the main differentiating factor between a PC and a terminal.
Graphics Support
The philosophy that a thin-client should not require an embedded operating system presented a real challenge when faced with today’s GUI based MS Windows dominated office applications.
After investigating several technologies Axel decided that AT&T’s VNC (Virtual Network Computing) technology was the way forward. VNC is a remote frame buffer technology that works in conjunction with a Unix/Linux server. The GUI image is built and maintained within the memory of the Linux server, and only the pixel and keyboard/mouse data is transmitted across the LAN to the Axel terminal. A default, generic Linux or SCO server is used, with one further program installed, the VNC server, so there is no administration to be performed on the Linux server. The VNC client is embedded in the Axel terminal, and can co-reside with the character based emulations.
The VNC server and client software are available free of charge (GPL License) from AT&T’s website (http://www.uk.research.att.com/vnc/ ) in both source code and compiled for most common environments. Axel supply the same programs with Axel specific documentation.
Performance
As the application is physically run on the Linux server and only displayed on the terminal, there will need to be a certain amount of memory in the Linux server per VNC terminal (user). The amount of memory varies depending on the size of the program being run. A Linux based ICA or RDP (Citrix/Microsoft) client requires less than 8 Mb per user, Star Office or a browser will require around 32 Mb per user.
The GUI display is divided into a matrix 16x16 bit tiles and only the tiles that have changed are encoded and sent across the LAN, not the entire screen, so LAN traffic is not a major consideration.
The configuration described above results in each AX3000 terminal having its own Linux/SCO graphics desktop that any graphics program executable under X can be run. The most common applications include Citrix ICA, Microsoft RDP clients, various browsers and StarOffice.
Running Microsoft Applications (under RDP)
Rdesktop is an open source RDP client that runs on all versions of Linux and SCO. It opens an RDP connection to a Windows2000, NT4 TSE or Citrix server providing a genuine Microsoft desktop on the VNC terminal. The application is run on the Microsoft Server and displayed on the VNC terminal. Although the Linux server is an integral part of this solution, the users will not need to log onto it – or indeed be aware of its existence.
The Axel terminal has four concurrent sessions, so for example ‘Session1’ can ‘telnet’ onto the Linux/SCO server and run the character based unix application, and ‘Session 2’ will immediately offer the user a Microsoft login prompt, from where after logging in, any Microsoft application can be run. The user can then hot-key between these two sessions.
Other features
Cost
Cost is the driving force behind the thin-client revolution, both capital and cost of ownership. Personal computers are relatively expensive to buy, to maintain, and often obsolete in a couple of years.
By comparison the Ax3000 is based on a small custom built circuit board that is designed specifically for running terminal emulations. There is an enormous cost saving made possible through not having an embedded operating system or the hardware required to support it.
Axel
Axel is a European manufacturer with offices in France, Germany, UK and USA. We have been manufacturing terminals for over 12 years and offer a full family of terminals from serial terminals, TCP/IP terminals and thin-client graphic VNC terminals.
In conclusion the Ax3000 is a low cost, robust, silent, colour terminal in a stylish metal case, with no moving parts (except the on/off switch) that can simultaneously run applications on a Linux/Unix server and a Windows server without needing an embedded operating system.
This is Axel’s definition of true thin-client multi-platform computing.
Retail prices start from about £200.
For more information, contact Matthew Stones at Axel Technologies.
Last Updated: 29 Nov 2001