ABSTRACT : How a thin client computing works?Thin-client computing offers a solution tothe increasingly unmanageable costs of How a thin client looks like?todays IT infrastructure. Thin-clientcomputing moves user data and Thin client’s relation with cloud orapplication management from the desktop grid computing? Grid computing vs. utilityto centralized servers in professional- computing vs. cloud computing?managed data centres. Application serviceproviders (ASPs) are using thin-client 2. HISTORYcomputing to enable desktop machines, 3. ARCHITECTUREweb browsing terminals, and other low- 4. CHARACTERISTICScost embedded devices to function as Single point of failuresimple user interface devices for accessing Cheap client hardwarecomputational services over the Internet. Client simplicityASPs have the potential to deliver easier- Thin client securityto-maintain computational services with 5. TRENDS IN THIN CLINETreduced total cost of ownership. COMPUTINGA key enabling technology in thin-client 6. RECENT TRENDScomputing is the remote display protocol. Ultra-thin clientsThe protocol allows graphical displays to Web thin clientsbe served across a network to a client 7. APPLICATIONSdevice, while applications and even 8. COMPONENTS OF THIN CLIENTwindow systems are executed on the COMPUTINGserver. Using such a protocol, the client Thin client hardwaretransmits user input to the server, and the Thin client softwareserver returns screen updates to the client. Network connectivity The host serverTo assess the viability of the thin-client Thin client protocolscomputing model, we are conducting a 9. ADVANTAGESseries of detailed experiments to quantify 10. DISADVANTAGESthe performance of thin-client platforms 11. CONCLUSIONfor various application workloads. We 12. REFERENCESfocus on the network performance ofremote display technologies. Our 1.INTRODUCTION:experiments include measurements ofpopular thin-client platforms such as WHAT IS THIN CLIENT?AT&T VNC, Citrix Metaframe, MicrosoftTerminal Services, Sun Ray, andTarantella. . A thin client can refer to either a software program or to an actual computer thatCONTENTS: relies heavily on another computer to do1. INTRODUCTION most of its work. A thin client is part of a network, and the client software or What is thin client? computer acts as an interface, while the network server computer does all the real work. In the case of a computer, a thin
client is unable to perform many functions Thin clients are also relatively easy toon its own. A thin client computer may be secure. A thin client user has restricteda machine designed only for online use, access to programs or functions that couldsending and receiving email, and surfing breach security. Restricting all the realthe net. A thin client computer may also be computing power to a single networkpart of a larger network, at a company or server also means that all the security canschool for example. be focused in one place.The thin client computer contains enough HOW A THIN CLIENT COMPUTINGinformation to start up and connect to a WORKS?more powerful network server, and theserver computer provides the rest of the A thin client can be a low-powered PC (forcomputing horsepower. The thin server example, a 486-based computer runningmay not even have a hard drive. If the thin Windows 3.x to access a Windows 2000client computer needs to use a program or desktop through a Win2K terminal server),save a file, it will connect to the network a terminal that boots from and downloadsserver computer to do so. its operating system from a boot server, or a device running Windows CE or anotherIn software terms, a thin client is a embedded operating system. Client (orprogram which is mostly interface. The terminal services client) software can alsouser of the thin client software sees all the be run on DOS, Linux, and Macintoshdata, tools, and features they would on a systems.normal piece of software, but anotherprogram running on a remote server doesall the work. The reasons someone mightuse a thin client, both hardware andsoftware versions, include reduced cost,ease of maintenance, ease of use, andsecurity.A thin client is much more simple than acomplete computer. In a situation in whichmany people need to perform a similartask, it is more cost effective to have onenetwork server computer and many Individual “sessions” or virtual machinesinexpensive thin client computers, than to are created on the server, so that multiplehave many complete computers. Because users can access their individual desktopsthin clients are relatively simple, it is much simultaneously. Printing, audio output, etc.easier to diagnose problems and repair can be redirected to the local clientthem. A standard computer has a lot of machines.parts, and a thin client only has a few.Fewer parts mean fewer things can go HOW THIN CLIENT IS LOOK LIKE?wrong.People who are not as computer literatewill have an easier time using a thin clientthan a standard computer or softwareprogram. With fewer features andfunctions, a thin client means a person hasfewer things that they need to learn about.
Grid computing links disparate computers to form one large infrastructure, harnessing unused resources. Utility computing is paying for what you use on shared servers like you pay for a public utility (such as electricity, gas, and so on). With grid computing, you can provision computing resources as a utility that can be turned on or off. Cloud computing goes one step further with on-demand resource provisioning. This eliminates over- provisioning when used with utility pricing. It also removes the need to over- provision in order to meet the demands of millions of users. GRID COMPUTING VS. UTILITY COMPUTING VS . CLOUD C OMPUTING:THIN CLIENT’S RELATION WITH CLOUDOR GRID COMPUTING? Grid computing is a collection of servers that are clustered together to attackTo get cloud computing to work, you need a single problem. For a period of time, thethree things: entire resources of the grid are available to an user to tackle a particularly difficult thin clients (or clients with a thick- compute problem. The engineering of such thin switch). a grid requires complex inter-cluster grid computing. networking, and usually the tuning of a grid is not for the faint of heart. utility computing. Utility computing and cloud computing are similar in terms of the customer value proposition. Both are about a shared compute resource, where users can get more or less resource on-demand. The critical difference vis-a-vis a grid is
that a single user at a given point only gets relatively popular thin clients in the 1990s.a small portion of the utility or the cloud. Modern Unix derivatives like BSD and GNU/Linux continue this multi-user Architecturally, IMO they are tradition.fundamentally different, though both try toprovide similar customer benefit. Cloud Windows NT became capable of multi-infrastructure (compute or storage) is user operations due primarily to the effortsabout leveraging commodity hardware, of Citrix Systems, which repackaged NTand using the power of software to slice, 3.5.1 as the multi-user operating systemdice and scale-out capacity and Win Frame. Microsoft licensed thisperformance, while delivering a service technology back from Citrix andover a network(internet or intranet). Utility implemented it into Windows NT 4.0computing as popularized by the goliaths Terminal Server Edition, under a projectin the industry was really pretty much the codenamed "Hydra." Windows NT thensame infrastructure from the familiar firms became the basis of Windows 2000 andwith 3-letters (EMC, Sun, IBM etc.) but Windows XP. Today, Windows allowswith a bill-on-demand front-end. You graphical terminals via its Remote Desktopwheeled in the same racks, except the Services component.billing-engine only made capacityavailable on-demand. The term thin client was coined in 1993 by Tim Negris, VP of Server Marketing at Ultimately utility storage, proved Oracle Corp., while working withto be ho-hum, as the solutions were company founder Larry Ellison on thestovepiped and closed, and the economies launch of Oracle 7. At the time, Oraclewere not quite there, and the promise wished to differentiate their server-remained undelivered. For example, Sun oriented software from Microsoftsshuttered its utility compute business in desktop-oriented products. NegrissDecember of last year, with Sun’s cloud buzzword was then popularized by itsbusiness subsuming the same value frequent use in Ellisons speeches andproposition. interviews about Oracle products. With commodity economics, 3.ARCHITECTURE:shared access over the internet or theintranet, highly flexible software basedmanagement, cloud computing(andstorage) looks set to deliver on what utilitycomputing promised.2. HISTORY:Thin clients have their roots in multi-usersystem, traditionally mainframes accessedby some sort of terminal computer. Ascomputer graphics matured, theseterminals transitioned from providing acommand-line interface to a full graphicaluser interface, as is common on modernthin clients. The prototypical multiuserenvironment along these lines was Unix,and fully graphical X terminals were 4.CHARACTERISTICS:
very low-power and might not even require cooling fans, but the servers are higher-power and require an air- conditioned server room. On the other hand, while the total cost ofSingle point of failure: ownership is low, the individual performance of the clients is also low.The server, in taking on the entire Thin clients, for example, are not suited toprocessing load of several clients, forms a any real form of distributed computing.single point of failure for those clients. The costs of compiling software, renderingThis has both positive and negative video, or any other computationallyaspects. On the one hand, the security intensive task will be shared by all clientsthreat model for the software becomes via the server.entirely confined to the servers: the clientssimply dont run the software. Thus, only a Client simplicity:small number of computers need to berigorously secured, rather than securing Since the clients are made from low-costevery single client computer. On the other hardware with few moving parts, they canhand, any denial of service attack against operate in more hostile environments thanthe server will harm many clients: so, if conventional computers. However, theyone user crashes the system, everyone else inevitably need a network connection toloses their volatile data; if one user infects their server, which must be isolated fromtheir computer with a virus, then the entire such hostile environments. Since thinserver is infected with that virus. clients are cheap, they offer a low risk of theft in general, and are easy to replaceFor small networks, this single-point of when they are stolen or broken. Since theyfailure property might even be expanded: dont have any complicated boot images,the server can be integrated with file the problem of boot image control isservers and print servers particular to its centralized to the central servers.clients. This simplifies the network and itsmaintenance, but might increase the riskagainst that server.Cheap client hardware:While the server must be robust enough tohandle several client sessions at once, theclients can be made out of much cheaper On the other hand, to achieve thishardware than a fat client can. This simplicity, thin clients are generally highlyreduces the power consumption of those integrated systems. This means that theyclients, and makes the system marginally may lag behind thick clients in terms ofscalable: it is relatively cheap to add on a extensibility and accessibility. Forcouple more client terminals. The thin example, if the server does not haveclients themselves in general have a very support for independent audio streams, orlow total cost of ownership, but some of the communication protocols dont transferthat is offset by requiring a robust server such streams, one simply cannot receiveinfrastructure with backups and so forth. audio from the server. Similarly, if theThis is also reflected in terms of power client lacks USB ports, or if there is someconsumption: the thin clients are generally communication failure of its USB signals over the network, the client might be
wholly unable to support an unexpectedUSB peripheral. As thin client implementations grew more common and more cost-effective, otherThin client security: uses were found: Users could access programsSecurity is a top priority in all aspects of provided by an external applicationcomputer networking today; thin client service provider (ASP), eliminatingcomputing is no exception. Some the need for the company to licenseadministrators are implementing thin or maintain the applicationclients as a security solution; because the software.clients require no local disk drives and Walk-up browsing stations couldbecause administrators can better control be set up in common areas of offices, hospitals, malls, etc. tosessions that run on a centralized server, provide access to designatedthin clients are by their very nature easier applications.to secure than full-fledged PCs. Thin clients could be used asEven when PCs are used as the clients, stations at Internet cafés or infeatures such as Windows 2000 Terminal libraries where a number of peopleService’s ability to limit or restrict local need access to an application suchdevice redirection and set up other as a Web browser or database.security restrictions for individual users Thin clients could be used in themake it easier for administrators to educational environment, providingmaintain control. However, the terminal Internet and application access toserver represents a single point of failure; students in the classroom at a lowif its security is compromised, the cost.desktops/computing sessions of multipleusers will be affected. Thin clients could be used as remote access solutions, allowing5. TRENDS IN THIN CLIENT users to dial or VPN into aCOMPUTING: company network from a low- powered home computer to connectA few years ago, thin client computing to a terminal server and accessconcentrated primarily on providing access network applications.to applications on a server from low-powered desktop clients within a local Thin client kiosks could be set upnetwork. For example, if a number of to provide specific information oremployees had computer needs that limited access at airports, on salesincluded typing documents with a word floors, etc.processing program, using a spreadsheet Home users who only need e-mailapplication for accounting/record keeping, and/or Web capabilities and don’tsending e-mail, and perhaps using the Web need to run a “fat” operatingfor research, these users could be provided system, or high-poweredwith thin clients at their desks rather than applications could use a thin client.traditional PCs. The users could accessapplications that were running on a server, 6. RECENT TRENDS:saving money in hardware costs, andmaking application management easier for Ultra-thin clients:the administrator.
The notion of a thin client extends directly to any client-server architecture: in which case, a thin client application is simply one which relies on its server to process most or all of its business logic. This idiom is relatively common for computer security reasons: a client obviously cannot be trusted with the logic that determines how trustworthy they are; an adversary would A Sun Microsystems stateless S270 simply skip the logic and say "Im as thin client, sometimes called an trustworthy as possible!" ultra thin client Traditionally, a thin client ran a full However, in web development in operating system for the purposes particular, client applications are becoming of connecting to other computers. fatter. This is due to the adoption of A newer trend is sometimes called heavily client-side technologies like Ajax an ultra-thin client or a zero client, and Flash, which are themselves strongly which no longer runs a full driven by the highly interactive nature of operating system: the kernel Web 2.0 applications. instead merely initializes the network, begins the networking A renewed interest in virtual private protocol, and handles display of the servers, with many virtualization programs servers output. coming to a ripe stage, means that servers on the web today may handle many different client businesses. This can beWeb thin clients: thought of as having a thin-client "virtual server" which depends on the actual host in which it runs to do all of its computation for it. The end result, at least, is the same: amortization of the computing service across many clients. Moderro Xpack Web-centric Thin Client 8. COMPONENTS OF THIN CLIENT Web thin clients (running a Web COMPUTING: OS) rely on the web-based software for the application and Thin client computing requires a basic set data storage, thus eliminating the of components: thin client hardware single point of failure and the need for OS/application/data aggregation running thin client software, a network and licensing required by connection to a host server, and a common traditional thin client. thin client protocol for communication added security. Mobile devices will between the client and server. require special protocols Thin client hardware: As we’ve seen, the thin client can take a number of hardware forms. The most7.APPLICATIONS: popular include: The Windows-based Terminal (WBT): Microsoft has released a
standard for hardware vendors who make thin client products based on There must be a network connection the Windows CE operating system. between the client and server; thus, both Network PC (NetPC): This is a machines must be running a common low-cost PC that can be used as a networking protocol (typically, TCP/IP) thin client (with the proper and each must have a physical cabled software installed) and doesn’t connection or a wireless (such as radio or have a floppy or CD-ROM drive. It infrared) connection to the same network. is capable of booting from a network server. The network connection can also be remote, over phone or dedicated leased Network Computer: This is similar lines, or through a VPN, with both to the NetPC but is based on non- machines connected to the Internet. Intel processors and runs a Java- based operating system. The host server: Wireless Tablet: This runs an The server that will run the applications embedded operating system such as must be configured to allow thin client or Windows CE, is powered by a terminal connections. For example, a battery, and uses wireless Windows server must be running Terminal technology such as 802.11 to Services and configured through Terminal connect to the network. Services Manager as an application server Computing Appliance: This is a to allow multiple connections from non device running preinstalled administrative users. software; it usually doesn’t have a hard disk and often is designed Thin client protocols: primarily for Internet connectivity. The thin client protocol provides for “Fat” client: This is a full-fledged transmission of the user interface from PC running thin client software and server to client and transmission of user protocols and connecting to a input from client to server. The most server that runs applications. popular thin client protocols are: The Remote Desktop Protocol (RDP): This runs on TCP/IP as theThin client software: underlying network protocol and is used by Microsoft for WindowsThe client software required to access the Terminal Services. The content ofhost server may be preinstalled, or it may the user interface is transmitted asbe installed as an add-on program (for bitmaps. RDP is based on the ITUexample, you can install the Windows T.120 protocol as defined by theTerminal Services client or Remote International TelecommunicationsDesktop Connection (RDC) client on a Union. RDP allows for cutting andcomputer running Windows 3.x, 9x/Me, or pasting between the local2000. Note that the RDC client is already applications and terminalinstalled with the operating system on applications and printing to a localWindows XP Professional. You can install printer from terminal applications.the Citrix ICA client on Windows, The Independent ComputingMacintosh, Linux, and DOS computers). Architecture (ICA) protocol: The ICA protocol is much more robustNetwork connectivity: and includes more functionality
than RDP and is used by Citrix for Reliability: Because administrators their Winframe and Metaframe have control over the centralized products. Unlike RDP, ICA will system, thin clients are not subject run on IPX and NetBIOS, as well to the application errors that often as IP. It also allows for clients occur when users accidentally running on non-Microsoft delete files or change settings on platforms such as Linux, DOS, individual computers. Macintosh, and JAVA-based operating systems, and Physical size/footprint: Many of performance is faster due to the use the thin client systems are small of data compression. Citrix also and easy to transport. A low- offers a security package powered laptop that doesn’t have (SecureICA) for encryption and enough memory to run Windows authentication. 2000 can still access the Windows 2000 interface through Terminal The X Protocol: X can be used as a Services thin client protocol between UNIX- based systems (X server and X terminal) but is more limited in functionality since this is not the 10.DISADVANTAGES: use for which it was designed. Entry costs are high for servers and installation expertise.In addition to the networking transport More bandwidth is required;protocols and thin client protocols, other multimedia, project-based learningprotocols may come into play. Forexample, network security protocols, such applications run very slowly.as SSH, IPSec, and SSL/TSL can be usedfor IrDA, Bluetooth) for wireless Thin-client doesn’t allow thecommunication. Bootstrap protocols are flexibility to load software on thenecessary for booting from the network. spot, constricting the “teachable moment.”9.ADVANTAGES: PC’s are coming down in costs,Thin client computing provides the and many educators believe usersfollowing advantages over running need the fully-functioningprograms locally on networked PCs: capabilities of a desktop. Cost: Hardware for thin client machines is much less expensive than a full-powered PC. Management: Because all 11.CONCLUSION: processing is done on the server, management is centralized. For Thin client solutions are becoming more example, if an application needs to popular than ever. Terminal Services is be upgraded, the administrator only included in Windows 2000 server products has to upgrade it once on the and is further improved in .NET server. server, rather than on a number of Citrix, New Moon Systems, and other desktop computers. vendors provide add-on products that lend even more functionality to Windows Terminal Services. Linux-based terminals,
Java-based terminals, and otheralternatives abound and make it easier thanever for administrators to take advantageof the cost-effectiveness andadministrative control that comes withimplementing thin clients. As wireless thinclients become more common and moreaffordable, the popularity of server-basedcomputing is sure to increase even more.12.REFERENCES:.http://en.wikipedia.org/wiki/Thin_client.http://www.thinclients.co.in/.http://www.search.com/reference/Thin_client.http://en.wikipedia.org/wiki/cloud_computing