From versatile desktop terminals to the next generation of mobile
phones, today’s thin client technology promises improved
reliability and manageability
Definition
A thin client is a device with limited processing power and
storage. It acts primarily as an interface between user and
applications hosted across a LAN/WAN or even the Internet. Unlike a
modern desktop PC, there are fewer components within a thin client.
The lack of hard disk and complex operating system increases system
reliability while reducing cost.
The development of the thin
computing modelAlthough the modern graphical user interfaced
terminals (WinTerm) are an improvement, the thin client concept is
essentially over two decades old. In the early 1960s, bulky
mainframe computers cost millions of pounds a year to install and
manage, while applications required thousands of man-hours to
develop and proved difficult to implement on more than one
architecture. These expensive systems often became computing
bureaus where multiple applications and users would be given an
allotted amount of computing time or connections for applications
or data processing. Each of the major mainframe manufacturers
required proprietary terminals from vendors such as RCA, IBM and
DG. This business model of low-powered dumb terminals connecting to
powerful servers was the forerunner of the modern thin client
model. When, in 1981, IBM unveiled their PC desktop computer, it
started the trend towards powerful and versatile desktop computing,
as opposed to the powerful mainframes/dumb-terminals of the
1970s.Popular graphic operating systems such as Windows and MAC-OS
further reduced the popularity of text-only terminals with their
green or amber displays. Within applications such as CAD and DTP,
the dumb terminal was no longer viable, and a wealth of new devices
such as scanners, laser printers and sound cards made this new PC
technology the preferred choice for the medium-sized
businesses.
Today's thin client solutionsThe modern thin
client has evolved immensely from the terminals of the 1960s. The
types of applications and user interfaces now resemble a hybrid of
modern desktop PC systems with the reliability of legacy dumb
terminals. The two basic types of thin client are Windows terminals
and ANSI/Console terminals. The latter are now much less popular
and generally connect to older mainframes and Unix systems. These
text-only terminals are often used in financial institutions and
data processing centres, or wherever older VAX and AS400 systems
have been deployed in depth.The newer and increasingly more popular
terminal type is the Windows Terminal. Although not exclusively
used with Microsoft Windows, these devices are able to display
text, graphics and output audio. The rise in popularity of the
WinTerm is mostly due to Citrix's WinFrame - launched in 1995 (now
Metaframe) - and Microsoft's NT terminal edition. The combination
of these two applications allows NT, Unix and Mainframe software to
run on centralised servers with only visual and keyboard
information carried over the network to each terminal. This visual
information is carried by a protocol layer, usually over ICA
(Citrix) or RDP (mostly Microsoft). Of the two common protocols,
Citrix's ICA using Metaframe is by far the most advanced, offering
many additional scalability and security features. However, it does
add further expense to any thin client solution. Another reason for
Metaframe's popularity is the large number of computing
environments it supports. As well as all the Microsoft Windows
varieties, Version 1.8 also has clients for DOS, Unix (9 Flavours),
MAC, Java, ActiveX and the popular Explorer and Netscape browsers.
RDP, on the other hand, is a more open protocol, stemming from the
T.120 international communications standard. Microsoft, and thin
client vendor, NCD, are both adding extensions to the original RDP
specification. These improvements are starting to bring the
features offered by RDP into line with the rival ICA protocol.
Unfortunately, these advances also make RDP less universally
compatible between vendors. Potentially, a VHS versus Betamax
standards war could occur which could ultimately render one type of
technology obsolete, or conversely develop a new "super" standard
with the best of both worlds. The development of the rival ICA/RDP
protocols has also provided multimedia features for thin client
systems. Applications complete with video and audio streaming is
now commonplace because of these two standards.Deploying a thin
client system is also far removed from the highly proprietary and
quirky solution of the past. Modern thin clients use standard
Ethernet connections with TCP/IP, while support for IPX/SPX and
NETBUI are also available under Metaframe. Modern applications that
are best suited to the thin client model include CRMs within call
centres, database interaction and simple office applications such
as word processing and spreadsheets. With the majority of offices
now wired for CAT-5 cabling, attaching a thin client to a LAN is
very simple. Centralised servers running NT and NetWare now offer
limited support for thin clients, straight out of the box.
Main
advantageThe main advantage that thin client manufacturers
always stress is total cost of ownership (TCO). The theory is that
simple, low-cost terminals offer increased reliability, while
having all your applications on a centralised server may also
relieve the support burden. Support is crucial. Having to upgrade
and support software in an office full of desktop PCs is a constant
worry for IT departments. Thin clients allow centralised upgrades
and support. Security again is another area where this technology
offers many significant advantages. With only a central point of
entry for possible viruses or unauthorised software, system
administrators can better focus their security efforts. As all
information must also pass through a central server for processing,
access to sensitive data and unauthorised usage can be monitored or
suspended. For end users familiar with the Windows interface and
applications, the re-training required to use Windows terminals is
minimal.
Main disadvantagesThere are several issues that need
to be considered when deploying thin client technology. Although
the claims of TCO are impressive, thin clients do involve placing
all your eggs in one basket to a certain extent, leaving users open
to the dreaded total loss of service. With no local processing
power, the thin client is totally dependent on both server
resources and network availability.With large installations, having
a switched network is essential. Considering that each connected
terminal utilising the ICA protocol will commandeer between 14k to
32k per connection, 100Mb Ethernet is often required for large
installations. For power users, or those with a requirement for
local devices such as scanners, printers or even PDA's, thin
clients are much less flexible.
Vendors and manufacturersThe
thin client market is still fairly diverse in terms of vendors.
Companies such as Wyse and IBM, who dominated the old dumb terminal
market, have flourished in the new WinTerm era. These have been
joined by a host of traditional PC vendors such as Compaq and
Hewlett Packard. Currently, Wyse is still the global leader in the
thin client market, with nearly 38 per cent market share (IDC),
combined with a considerable share of the OEM market. A major
competitor is NCD, who though having a smaller installed base, are
now trying to offer additional value through an innovative software
suite aimed at rivalling the dominance of Citrix's Metaframe. On
the software front, Citrix are still the largest player in the thin
client market, but now that Microsoft has seen the potential for
thin client computing, support is now starting to appear in Windows
2000 as standard.For the thin client market, Windows 2000 may be
the catalyst for a greater acceptance of thin clients over "fatter"
PCs. The network version of the new 2000 edition has a number of
features for smoothly implementing a thin client solution. These
include load balancing and remote administration, although these
are far less effective than dedicated systems such as Metaframe or
ThinPath.
The future of thin clientsThe future will see the
rise of the thinnest device to date - the mobile phone. At the
moment, the modern cellular telephone has most of the requirements
to qualify as a thin client: it has a permanent connection to a
network; it has high reliability and its services are provided from
a central source. Unfortunately, entering and receiving data is
still inefficient in its present form factor. Thin client
manufacturers and mobile phone companies are all working closely on
technologies such as WAP and Bluetooth, and the merging of the
cellular telephone and PDAs, coupled with advances in voice
control, should see some groundbreaking products emerging over the
next few years.One such innovative new product is Sun
Microsystems's SUNRAY 1, although SUN would prefer to forget their
previous foray into thin client computing with the ill-fated NC
(Network Computer). When in 1996, Scott McNealy (Sun CEO) unveiled
the "revolutionary" Java-based NC, he suggested that customers
should "take the money you'll save from not having to invest in
another mainframe, from not spending on the Year 2000 [problem],
and not having to upgrade your desktop PCs, and put it into the
Java-computing model". Unfortunately, they didn't. After three
years and a handful of sales, this brave product was quietly
shelved, leaving Sun several million dollars worse off.The
development work that created Java-station was still useful and
Sun's second generation NC, Sunray 1, is potentially a new
direction for thin client converts. Sunray is described as the best
of Solaris reliability with the popularity of Windows applications
such as Exchange, Access and MS Office. The individual, coffee
percolator-style appliances attach over a switched network to a
Solaris server. This server can run any Solaris application and
provide Internet connectivity. Additional NT servers can attach to
the Solaris server allowing MS applications to be served straight
to each Sunray unit. Market leader, Wyse Technologies, is also
developing several new thin client innovations. In a recent
interview with ITNetwork.com, Dave Mills, European director of
marketing outlined the new Thincard concept."Thincard is the next
evolution of silicon and firmware which will ultimately result in
all the functionality of a thin client on a single chip."Although
only in a concept stage, the Thincard looks similar to a PC
(formerly PCMCIA) card and contains a microprocessor, video chip,
RAM and operating system. To increase connectivity, Thincard will
also have USB sockets for a range of peripherals. Mills continues:
"We envisage that within five years IT professionals may well have
a Thincard in their wallet, simply plugging the card into a network
attached device to access a virtual desktop, anywhere in the
world." Already some computer monitor manufacturers are already
interested in including Thincard slots for concept displays of the
future. Whether Wyse's Thincard or another rival develops this
concept, if used in conjunction with high bandwidth cellular
technology (HSCD), it could provide a wireless and highly portable
thin client solution unlike anything seen to
date.
SummaryThin Client technology is gaining popularity.
According to International Data Corporation's August 1999 report,
thin client unit shipments in Western Europe had reached 1,800,000.
The value of this worldwide market has been estimated to grow to
$2.38billion by the year 2001, with an installed base of 14.5
million. The Gartner Group predicts that half of all applications
will be run on thin clients by the same year.This upward trend may
be a reaction to the spiralling support costs associated with
computing systems. Now that IT departments have to support desktop
applications, mobile users, network and intranet services, moving
some of their computing operations to a thin model is starting to
look very tempting. The speed of technological innovation is also
forcing many companies to upgrade hardware every three years, an
expense which combined with disruption to business is lessened
considerably by thin computing. Moving from a fat to a thin client
model is not a simple task. However, as computing environments
upgrade to Windows 2000 or businesses start to explore the ASP
markets, thin client computing will become very attractive
indeed.
Will Garside