Thin
Client, Server Based Computing, Network Computing
A
thin
client is a simple client
program or hardware device which depends primarily
on the central
server for processing activities because it
has little or no application logic. In contrast
to a thick or fat client,
which does as much processing as possible and passes
only data required for communications and archival
storage to the server,
a thin
client is a network computer without a hard
disk drive, which, in client/server
applications, is designed to be especially small
so that the bulk of the data processing occurs on
the server.
The word "thin" refers to the small boot
image which such clients
typically require.
When
designing a client-server
application, the decision as to which parts of the
task should be done on the thin
client, and which on the server
can crucially affect the cost of thin
client and servers,
the force and security of the application as a whole,
and the flexibility of the design to later modification
or porting.
How
application-specific the client
software should be is another question. Using
standardized thin
client software
such as a Web browser or X11 display can save on
development costs, since one does not need to develop
a custom client—but one must accept the limitations
of the standard client.
Application
Program
A
thin
client as an application program communicates
with an application
server, relying on a separate piece of software
for the most significant elements of its business
logic. A thin
client does most of its processing at the central
server based computer (server
based computing), the thin
client with as little hardware and software
as possible, and as much as possible at some centralized
managed site.
However,
a great deal of software
today is typically included in the base boot image
of a thin
client, specifically to support various user
applications running at the server
based computing , so that it need not be reinstalled
on every computer. Often, a departmental boot image
is prepared to include applications specific to
a department.
User-Interface
Device
The
thin
client device is specifically designed to provide
just those functions which are useful for user-interface
programs. Because they may become corrupted by the
installation of misbehaved or incompatible software,
often such devices do not include hard disk drives.
But instead, in the interests of low maintenance
cost and increased mean-time between failures, the
thin
client device will use read-only storage such
as a CD-ROM, Network Virtual Drive, or flash memory.
The user will have only a screen, a keyboard, a
pointing device (if needed), and enough computer
to handle display and communications.
Thin
Client Software
Most
thin
clients are software-only and run on standard
PC hardware. One example of this software-only thin
client is Applica ThinWorks,
a smaller thin
client on the market, running in conjuction
with ApplicaServer
and offering the best solution in network computing.
ThinWorks
offers UXVGA graphics ports, with usb and audio,
capable of running real time movies from the ApplicaServer.
The system is based on RDP protocol and represents
the best remote desktop available in the maket.
ApplicaServer
thin
computing from Applica offers the total solutions
to run multiple thin
client remote desktops on Windows XP.
Examples
of Thin Client and Thick Client Usage
A
few situations may clearly call for one or the other
two approaches. Distributed computing projects such
as the big offices (whose whole point is to pass
off computationally intensive analysis to a large
collection of remote computers) are applications
that require thick clients. On the other hand multicasting
entertainment or educational material to a number
of clients
might best be done with thin
clients since exactly the same material is to
be presented at each.
Some
technologies such as Network Virtual Disks or Disk
Drive Images are aimed to provide central management
and security/reliability/affordability comparable
to what is found in thin
client devices: the OS that operates the client
is stored on a shared virtual disk image (a disk
image file) that is housed on a server
in the clients'
LAN. This virtual disk drive is "write protected"
and shared by several clients
at the same time. The content of this virtual disk
drive is streamed on demand to the clients.
Yet, all the computing is done by the client
itself. Instead of centralizing a complete computer
(centralize the storage, CPU, memory, devices etc)
this approach centralizes only the hard disk drives.
Because the virtual disk drives can be shared and
protected, the aim to reduce TCO is also achieved
with this technology. This technology can be used
to run typical Embedded Operating Systems such as
Embedded Linux and Windows XP Embedded, but also
to run desktop operating systems such as Microsoft
Windows XP Pro, FreeBSD or Linux. Organizations
that develop and market Network Virtual Disks include
Linux Terminal Server Project, IBM (iBoot technology).
Network ffBlock Device support is another kind of
Network Virtual Disk embedded in Linux.
Advantages
of Thin Clients
Obviously,
boot image control is much simpler when only thin
clients are used - typically a single boot image
can accommodate a very wide range of user needs,
and be managed centrally, resulting in:
Lower
IT Admin Costs - Thin
clients are managed almost entirely at the server.
The hardware has fewer points of failure and the
local environment is highly restricted (and often
stateless), providing protection from malware.
Easier
to Secure - Thin
client can be designed so that no application
data ever resides on the client
(it is entirely rendered), centralizing malware
protection.
Lower
Hardware Costs - Thin
client hardware is generally cheaper because
it does not contain a disk, application memory,
or a powerful processor. They also generally have
a longer period before requiring an upgrade or becoming
obsolete. The total hardware requirements for a
thin
client system (including both servers
and clients) is usually much lower compared
to a system with fat clients. One reason for this
is that the hardware is better utilized. A CPU in
a fat workstation is idle most of the time. With
thin
clients, memory can be shared. If several users
are running the same application, it only needs
to be loaded into RAM once with a central
server. With fat clients, each workstation must
have its own copy of the program in memory.
Lower
Energy Consumption - Dedicated
thin
client hardware has much lower enery consumption
than thick client PCs. This not only reduces energy
costs but may mean that in some cases air-conditioning
systems are not required or need not be upgraded
which can be a significant cost saving and contribute
to achieving energy saving targets.
Worthless
to Most Thieves - Thin
client hardware, whether dedicated or simply
older hardware that has been repurposed via cascading,
is useless outside a client-server environment.
Burglars interested in computer equipment have a
much harder time fencing thin
client hardware (and it is less valuable).
Hostile
Environments - Most
devices have no moving parts so can be used in dusty
environments without the worry of PC fans clogging
up and overheating and burning out the PC.
Less
Network Bandwidth - Since
terminal servers typically reside on the same high-speed
network backbone as file servers, most network traffic
is confined to the server
room. In a fat client environment, if you open a
10MB document that's 10MB transferred from the file
server to your PC. When you save it, that's
another 10MB from your PC to the server.
When you print it the same happens again - another
10MB over the network to your file server
and another 10MB back to the printer. This is highly
inefficient. In a thin
client environment only mouse movements, keystrokes
and screen updates are transmitted from / to the
end user. Over efficient protocols such as ICA this
can consume as little as 5Kbps bandwidth.
Advantages
of Thick Clients
Fewer
Server Requirements - A
thick client server does not require as high a level
of performance as a thin
client server (since the thick clients themselves
do much of the application processing). This results
in drastically cheaper
servers.
Better
Multimedia Performance - Thick clients
have advantages in multimedia-rich applications
that would be bandwidth intensive if fully served.
For example, thick clients are well suited for video
gaming.
More
flexibility - On
some operating systems (such as Microsoft Windows)
software products are designed for personal computers
that have their own local resources. Trying to run
this software in a thin
client environment can be difficult.
Summary
A
thin
client PC is a PC coupled with software to make
it look and function like a standard thin
client. Thin
client PCs provide all the advantages of thin
clients such as ease-of-management, reliability
and increased control while avoiding the known limitations
associated with typical thin-client
devices. The thin
client PC solution is secure by definition and
can support environments that need the locked-down
desktop control while still maintaining the flexibility
of a PC for local application and I/O support.
The
thin
client PC solution is perfect for all organizations
that require a full-function local Internet browser,
local applications and want to access the proven
benefits of server-based
computing such as greater control, scalability
and cost containment. IT teams also find this solution
ideal for terminal replacement or kiosks projects,
which can be implemented prior to investing in Microsoft
Terminal Services or Citrix MetaFrame.
Server
Based Computing
Server
based computing [SBC] model is where applications
are deployed, managed, supported and executed from
central
server farms. Screen, keyboard and mouse information
is exchanged between the client
and the server
farms. No applications actually reside and execute
on the desktop client-server
based computing delivers instant access to business-critical
applications and data at this central point
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| Applica
U2Lite
Applica
U2Lite locally supports an additional
station attached to the Host PC with USB Keyboard
and USB Mouse support. Independent audio can
be added with the Applica USB Sound Adapter.
Applica
U2Lite is the least expensive solution
for local station support such as kiosks and
home use. |
ApplicaDS
ApplicaDS
is combination of hardware and software that
allows many users to use one Windows PC simultaneously
and independently! All users have their own
Windows desktop and can work completely independent
- with no perceptible performance degradation. |
Applica
UGroup
Applica
UGroup allows the addition of 4 extra
remote users to the primary user's computer
by connecting an additional set of standard
keyboard, mouse and monitor as well as other
devices using USB technology. |
Summary
Server
based computing has been widely adopted by corporate
IT decision makers as the most efficient, flexible
and cost-effective system for application delivery
and administration. It addresses the challenges
of optimising application reach, speed and security
while significantly reducing operating costs. A
thin
client is a computer (client)
in client-server
architecture network computing which has little
or no application logic, so it has to depend primarily
on the central server
for processing activities.
