Thin Client Computing

Thin Client Computing

ContentsExecutive Summary.....................................................................................................................................3

Introduction.................................................................................................................................................4

History.....................................................................................................................................................5

What is Thin Client?................................................................................................................................5

Architecture.............................................................................................................................................7

Typical Thin Client Architecture with J2EE framework.........................................................................9

Why Thin Client Computing?...................................................................................................................10

Hardware...............................................................................................................................................10

Centralized Support...............................................................................................................................10

Bandwidth Conservation.......................................................................................................................11

Power saving.........................................................................................................................................11

Licensing...............................................................................................................................................11

Security.................................................................................................................................................12

Protection from External Attacks...........................................................................................................13

The pros and cons of centrally managed antivirus software...............................................................13

Speed of deployment, repair and replacement.......................................................................................14

Issues with Thin Clients............................................................................................................................15

User acceptance.....................................................................................................................................15

High performance environments...........................................................................................................15

LAN/WAN resilience............................................................................................................................16

Legacy applications...............................................................................................................................16

Conclusion.................................................................................................................................................17

Appendix A...............................................................................................................................................18

Thin Client platform Characteristics......................................................................................................18

References.................................................................................................................................................19

Great Lakes Institute of Management Page 2


Executive Summary

The last two decades have seen computing shifting from Mainframe computing to the more

distributed model of desktop computing. As the Desktop computers gained prominence in the

corporate and academic organizations, the cost of maintaining and updating them in accordance

with the rapidly changing technology has proven to be a difficult and resource consuming job. In

addition to this, updating the software installed on individual machines and version monitoring

and control gets very complicated if the machines are spread over different geographies. In

response to these problems, there is a growing need being felt to return to a more centralized and

resource saving model of computing. The Thin-Client computing model is one of the results of

the effort taken in this field.



Introduction

A thin client, also called a lean or slim client, is a computer or software which depends on some

other computer to perform its traditional computational roles. This stands in contrast to the

traditional Thick Clients, computers designed to take on these roles by them. The ‘other’

computers providing support to connected Thin Client Computers are called servers. They are

designed in such a way so as to provide data persistence and actual processing on the behalf of

the client computer.

A thin client computer often has a low end terminal providing a graphical user interface to the

user along with the input/ output devices. There is a small RAM and network drive within the

terminal and the remaining functionalities including the operating systems are provided by the

server.



History

Thin Clients first came in the form of the mainframe computers which were heavy duty

machines accessed by multiple terminal computers. As technology matured, these computers

matured from providing just command line interface to a complete graphical user interface.

These machines ran on Unix and Unix type environments like BSD and Linux. After the arrival

of Windows NT, Citrix Solutions was able to provide a multi user operating system known as

WinFrame which later became Metaframe and later Xen App. The term Thin Client was coined

in 1993 by Tim Nigris and soon found place in popular usage.

What is Thin Client?

Thin clients are network-based computing devices that use the resources of servers to store

applications and data and deliver them to users. Individuals who sit in front of thin clients may

see a familiar Windows desktop environment that looks and feels virtually identical to that of a

traditional PC; thus, no user training is necessary. However, unlike many PCs used in business

environments, thin clients are in the complete control of the IT department, and all connections

to the outside world happen through a centralized, easily managed source. Therefore, unlike

traditional client PC/server IT environments, where each device has to be closely monitored for

Potential security breaches and the opportunity to create independent connections to the Internet

is a very real possibility, all Web connections, email, applications, and data for thin clients on a

given network come through a single point.

The goal of the thin-client model is to centralize computing resources, with all the attendant

benefits of easier maintenance and cheaper upgrades, while maintaining the same quality of

service for the end user that could be provided by a dedicated workstation. In a thin-client



computing environment, end users move from full-featured computers to thin clients, lightweight

machines primarily used for display and input and which require less maintenance and fewer

upgrades. Organizations then provide computing services to their end users' thin clients from

high-powered servers over a network connection. Server resources can be shared across many

users, resulting in more effective utilization of computing hardware.

Therefore, the core idea of modern Thin Client platforms is the use of a remote display protocol.

This technology enables graphical displays to be served across a network to a client device while

all application processing is performed at the server. The client transmits user input to the server

and server returns screen updates to the client.



Architecture

The fundamental approach behind thin-client computing dictates that; instead of running

applications locally on individual PCs with all of their associated challenges and costs. The

typical thin-client platform consists of a client application that executes on a user's local desktop

machine and a server application that executes on a remote system. The end user’s machine can

be a hardware device designed specifically to run the client application or simply a low-end

personal computer. The remote server machine typically runs a standard server operating system,

and the client and server communicate across a network connection between the desktop and

server. The client sends input data across the network to the server, and the server returns display

updates.

There are many design choices to be made within this basic framework, and as the results of our

testing demonstrate, these can have a dramatic impact on the performance of these systems. We

studied a wide range of current systems to reach our conclusions, including Citrix Metaframe

and Microsoft Windows Terminal Services (both the Windows NT and Windows 2000 versions

of these systems), AT&T , VNC, Sun Ray, and LapLink.

In Thin client system, applications run centrally with only keyboard, video and mouse (KVM)

updates transmitted across the network. Bandwidth usage is minimal compared to traditional

PC/server environments, with wireless LAN being ideal for the clients. The server backbone

linking the terminal servers, data servers, mail servers, and so on is the only LAN connection

that needs high capacity.



Thin Client model is geared towards a centralized system of computing with the benefits of

easier maintenance and economical and uniform upgrades, while maintaining the same quality of

user experience and computing capacity. Thin Client terminals are lighter machines with input

and output devices and small flash memory, connected via the network to highly powered

servers. Keystrokes and mouse clicks go to the server where the computing is done and output is

sent back to the terminal. All data is stored not locally but at Centralized data centers. Thus

connectivity to a User’s virtual desktop becomes independent of the physical machine being

used. The upgrades etc are done at the server level and there is hardly any need to make any

changes in the client terminals. It also helps in implementing Standardized Desktop policy across

large organizations.


Application Server

Internet enabled UIClient browser IE 6.0 or above

EJB

Oracle 9i,10g server / DB2 ver8.0 server

2nd tierApplication

1st tierThin client

3rd tierDatabase layer

Web Server

JDBC 2.0


Typical Thin Client Architecture with J2EE framework

Because of its so many potential cost and convenience benefits of Thin Client, many large

corporate and academic organizations across the world have started transitioning from Thick

Client to Thin Client machines. Some of the players providing Thin Client Services in the market

are: Wyse, Citrix, AT & T, IBM etc. A lot of application platforms have been developed for this

technology which provides a Virtual Windows/ Mac like Desktop environment to the user. Some

of these Application Servers are Citrix Metaframe, Xen App, Microsoft Terminal Service etc.

These Application servers are accessible over the Internet using Internet browsers and are quite

easy to use.



Why Thin Client Computing?

Hardware

Constant innovations in the Computing technology have made it a big challenge for the

corporations and academic institutions alike to cope up with the rapid advancement in hardware.

The average accepted life of a PC is 2 years, although often depreciated over 3 years. As a PC is

getting obsolete for a particular need, it is reallocated, often needing new hardware and software

build.

Thin Client computing tackles this issue by integrated updating. PCs are replaced by dumb

terminals for their useful life and all the Software/ hardware upgrades are done at the Server end,

later delegated to the thin terminals.

Centralized Support

Thin Client helps in centralizing the support process, especially for the software. This is even

more cost saving when the user base is widely spread over different geographies.

Thin Clients come with the Remote Takeover or Shadowing ability wherein Support personnel

can control the desktop of a user and resolve the issues. In a usual remote takeover, performance

is very slow if the machines are not on the same physical server. In Thin Client computing,

however, there is no performance drop issue as all the users are running on the same network.



The provision of having Centralized servers and support means not having the need to keep

support staff at the remote sites for server support. This reduces the cost of maintenance to a

great extent.

Bandwidth Conservation

A study done by Microsoft and NEC shows that the highest bandwidth user is the one who is

performing the same task repetitively. Switching to a thin client helps reduce the bandwidth

consumption to a great extent as the net bandwidth use is very less in thin clients as compared to

the thick clients. Far less bandwidth is required for remote and local sites, further reducing the

bandwidth costs.

Power saving

Power consumption of a thin-client device is about 15% when compared to a PC. Reduced

cooling requirements also lower the costs. Since a thin-client device will be expected to have a

useful life beyond 5 years, the power savings alone will offset 25% of the cost of those devices.

Licensing

Licensing is a major component of IT expenditure. The difficulty of supplying software when

needed has led businesses to adopt one of two approaches; deploy software to all PCs and lock

users out of those applications that they are not licensed for or purchase licenses for every PC,

regardless of whether the application will be used or not.



Security

One of the main issues with a thick-client environment is the inability to control precisely how

the information security is ensured. Data is always at a risk in this environment, with users often

taking data home to work on a document, thus putting the information at risk. With thin-clients

having no facility for local storage, this concern is almost eliminated in a thin-client computing

environment. On the contrary, if setup correctly, the security of the network can actually be

enhanced by adding levels of encryption to the network data. One other benefit is that it can be

accessed from anywhere but cannot be copied or saved on host computer. Work conducted from

outside of the office environment, for example at home, can be done through an internet

connection. The data remains at the server and is stored at the various data centers. There is

simply no need for it to ever be taken offsite, other than during controlled backup storage

routines. As long as e-mail security is addressed, the risk of potential leak for confidential data

remains minimal.





Protection from External Attacks

By eliminating the need to handle data locally, the scope of External attacks like is greatly

reduced. Since the majority of thin-client devices do not physically have floppy and CD drives,

this concern is non-existent. In common with thick-client environments, the servers must still be

adequately protected, particularly where e-mail is concerned. The lower-risk and cost benefits

come from not exposing the desktops.

The pros and cons of centrally managed antivirus software

With a centrally managed antivirus solution, there is the benefit of downloading the virus

signatures/definitions and software updates to a single server, thus requiring only one

machine to be connected to the Internet on that port. Once the update files are

downloaded, the PCs can then pull them from the server and not the Internet. This is a

better solution for organizations with limited Internet bandwidth or organizations that

don't provide downloading rights on every PC.

Despite their advantages, centrally managed antivirus solutions are not without

drawbacks. Because such systems store the virus signature/definition files in a single

location—usually a network server—this server becomes the single point of failure for

the entire system. In case of a server crash, all workstations will be without a way to

update their virus signatures. However this risk can be mitigated by having a load

balanced server and data center with Primary and Secondary servers and COB servers

connected to Load balancers



Speed of deployment, repair and replacement

Thin-client computing environments typically enjoy faster deployment times for new software

and upgrades. Fewer IT staff is required to track and ensure successful distribution. In a thick-

client managed environment, an application is tested in a lab, packaged, scripted and then

advertised to clients for automatic delivery. The clients will pick up the advertisement at an

interval predetermined by the administrator with due regard to bandwidth issues. Regardless of

the delivery software used, it is difficult to get all the systems upgrades in the first go itself. It

takes some time for a package advertisement to start being collected by PCs, a couple of hours at

an average. Without manual intervention from IT support staff, remote sites will take even

longer. For critical, security or virus related updates, this delay can be unacceptable.



Issues with Thin Clients

User acceptance

One of the major challenges to thin-client computing is getting the user acceptance, before,

during and after deployment. Outside a managed environment, users will have had access to their

disk drives along with the ability to install software on their own PCs or add screensavers. Whilst

this approach is great for employee relations, it is not so great for security and enhances

performance of the computers.

User acceptance begins at the top and management buy-in to this principle is essential. Problems

can also be prevented by using enterprise management tools. The rights come at a cost in terms

of infrastructure and bandwidth. Whilst dummy terminal-client devices may permit some of this

functionality to be retained, in a true thin-client environment, they will not. This is not as big a

problem it is initially perceived to be as very few users actually need to use disk drives, although

there are ways to provide access to those that do.

High performance environments

In a thin-client computing environment, all processing is done at the server and the KVM

refreshes are transferred via the network. By their very nature, CAD, terrain modeling and DTP

environments have constant screen redraws, which may increase network traffic to an

unacceptable degree thus increasing the latency.



Generally, such types of applications are not suited to a thin-client model, though a hybrid model

may be feasible. However, if Object Linking and Embedding is required, even a hybrid model

will not be able to perform optimally and Thick client should be provided for such users.

LAN/WAN resilience

Thin-client computing relies on constant connectivity between the server and the client. If this

connectivity is disturbed, clients cannot continue working, although their current session will

remain in the state it was in at the time the link was lost. Therefore, LAN/WAN resilience is

vital. In high-availability environments, best-practice recommends that alternate path and

supplier routing, particularly for WAN links, exists. This may increase year 1 costs over a fat-

client environment, although, since each of these links do not need as much bandwidth as before,

year 2 and onwards costs will be lower.

Legacy applications

With the advent of terminal services, several users will be using the same PC (the terminal

server) simultaneously to access the same application. Software certified for Windows 2000 will

adequately resolve the potential problems associated with this, by tracking registry keys and

ensuring that individual user settings do not overwrite system settings. Legacy software

generally does not do this tracking and so the scope for conflicts between settings is greatly

increased. These conflicts can normally be resolved, but it is crucial that adequate testing and

redesign takes place.



Conclusion

Thin-client computing is an important option to consider in any organization’s strategy. If

implemented correctly, it can significantly lower the operating costs and increase the quality of

support plus reducing the Information security risk. The key is assessing and planning the

deployment correctly. In order to avoid actually increasing the operating costs, it is vital that

relevant assistance from independent partners is obtained. The costs associated with this will

often be offset by the significant savings achieved.

In a nutshell, Thin-client computing is highly useful in the following cases:

Standard applications certified with Windows 2000 are in use

Currently not running a managed environment

The enterprise is very distributed, with many WAN links across different geographies

The LAN requires upgrading;

The client devices have lived their useful life and are nearing replacement date.

Thin-client computing will not be of much use in the following cases:

The workforce consists mainly of high performance users

Currently running a fully managed environment

There are many legacy applications with high migration costs



Appendix A

Thin Client platform Characteristics



References

1. Pilot Experiments for disaster Recovery in Private Cloud and Physical environment- Dr

Sunil Nakrani, Tata Consultancy Services

2. A Comparison of Thin-Client Computing Architectures - Technical Report CUCS-022-

00, November 2000

3. Thin Client Benefits – Barrie David, Newburn Consulting, 2002

4. www.thinclient.org

5. www.wyse.com

6. Boca Research, "Citrix ICA Technology Brief." Technical White Paper, Boca Raton, FL,

1999.

7. Citrix Systems, "Citrix MetaFrame 1.8 Backgrounder", Citrix White Paper, June 1998.

8. T. W. Mathers, S. P. Genoway, Windows NT Thin Client Solutions: Implementing

Terminal Server and Citrix MetaFrame, Macmillan Technical Publishing, Indianapolis,

IN, Nov. 1998.

9. T. Richardson, Q. Stafford-Fraser, K. R. Wood and A. Hopper, "Virtual Network

Computing." IEEE Internet Computing, 2(1), Jan/Feb 1998.

10. Tolly Research, "Thin-Client Networking: Bandwidth Consumption Using Citrix ICA,"

IT clarity, Feb. 2000.

11. S. J. Yang, J. Nieh, "Thin Is In," PC Magazine, 19(13), Ziff-Davis Media, New York,

NY, July 2000.

12. Evaluating Thin Client Security in a Changing Landscape – Intel Infromation

Technology, Apr 2010


Documents

Thin Client Computing