In computer networking , a thin client, sometimes called slim client or lean client , is a simple (low- performance ) computer that has been optimized for establishing a remote connection with a server -based computing environment. They are sometimes known as network computers , or in their simplest form as zero clients . The server does most of the work, which can include launching software programs, performing calculations , and storing data . This contrasts with a rich client or a conventional personal computer ; the former is also intended for working in a client–server model but has significant local processing power, while the latter aims to perform its function mostly locally.
50-957: Thin clients occur as components of a broader computing infrastructure, where many clients share their computations with a server or server farm . The server-side infrastructure uses cloud computing software such as application virtualization , hosted shared desktop (HSD) or desktop virtualization (VDI). This combination forms what is known as a cloud-based system, where desktop resources are centralized at one or more data centers . The benefits of centralization are hardware resource optimization, reduced software maintenance , and improved security . Thin client hardware generally supports common peripherals , such as keyboards, mice, monitors , jacks for sound peripherals, and open ports for USB devices (e.g., printer, flash drive, webcam). Some thin clients include ( legacy ) serial or parallel ports to support older devices, such as receipt printers, scales or time clocks. Thin client software typically consists of
100-455: A command-line interface to a full graphical user interface , as is common on modern advanced thin clients. The prototypical multi-user environment along these lines, Unix , began to support fully graphical X terminals , i.e., devices running display server software, from about 1984. X terminals remained relatively popular even after the arrival of other thin clients in the mid-late 1990s. Modern Unix derivatives like BSD and Linux continue
150-667: A data section (the payload data for the application). The UDP datagram header consists of 4 fields, each of which is 2 bytes (16 bits): The use of the Checksum and Source Port fields is optional in IPv4 (light purple background in table). In IPv6 only the Source Port field is optional. If not used, these fields should be set to zero. The method used to compute the checksum is defined in RFC ; 768 , and efficient calculation
200-407: A graphical user interface (GUI), cloud access agents (e.g., RDP , ICA , PCoIP ), a local web browser , terminal emulators (in some cases), and a basic set of local utilities . In using cloud-based architecture, the server takes on the processing load of several client sessions, acting as a host for each endpoint device. The client software is narrowly purposed and lightweight; therefore, only
250-500: A carry-out (17th bit) is produced, swing that 17th carry bit around and add it to the least significant bit of the running total. Finally, the sum is then ones' complemented to yield the value of the UDP checksum field. If the checksum calculation results in the value zero (all 16 bits 0) it should be sent as the ones' complement (all 1s) as a zero-value checksum indicates no checksum has been calculated. In this case, any specific processing
300-436: A challenge for thin clients. These use cases might include applications like photo editors, 3D drawing programs, and animation tools. This can be addressed at the host server using dedicated GPU cards, allocation of vGPUs (virtual GPU), workstation cards, and hardware acceleration cards. These solutions allow IT administrators to provide power-user performance where it is needed to a relatively generic endpoint device such as
350-411: A combination of TCP and TLS to ensure reliability and security respectively. This means that HTTP/3 uses a single handshake to set up a connection, rather than having two separate handshakes for TCP and TLS, meaning the overall time to establish a connection is reduced. Transmission Control Protocol is a connection-oriented protocol and requires handshaking to set up end-to-end communications. Once
400-480: A different header layout, the method used to compute the checksum is changed accordingly: Any transport or other upper-layer protocol that includes the addresses from the IP header in its checksum computation must be modified for use over IPv6, to include the 128-bit IPv6 addresses instead of 32-bit IPv4 addresses. When computing the checksum, again a pseudo header is used that mimics the real IPv6 header : The checksum
450-540: A high degree of reliability, a protocol such as the Transmission Control Protocol may be used instead. Most often, UDP applications do not employ reliability mechanisms and may even be hindered by them. Streaming media , real-time multiplayer games and voice over IP (VoIP) are examples of applications that often use UDP. In these particular applications, loss of packets is not usually a fatal problem. In VoIP, for example, latency and jitter are
500-433: A local drive. However, "thin client" can be a misnomer for slim form-factor computers using flash memory such as compactflash , SD card , or permanent flash memory as a hard disk substitute. In 2013, a Citrix employee experimented with a Raspberry Pi as a thin client. Since then, several manufacturers have introduced their version of Raspberry Pi thin clients. Server farm A server farm or server cluster
550-558: A project codenamed "Hydra". Windows NT then became the basis of Windows 2000 and Windows XP. As of 2011, Microsoft Windows systems support graphical terminals via the Remote Desktop Services component. The Wyse Winterm was the first Windows-display-focused thin client (AKA Windows Terminal) to access this environment. The term thin client was coined in 1993 by Tim Negris, VP of Server Marketing at Oracle Corporation , while working with company founder Larry Ellison on
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#1732772235071600-443: A server farm. The power used by each rack of equipment can be measured at the power distribution unit . Some servers include power tracking hardware so the people running the server farm can measure the power used by each server. The power used by the entire server farm may be reported in terms of power usage effectiveness or data center infrastructure efficiency . According to some estimates, for every 100 watts spent on running
650-644: A thin client. To achieve such simplicity, thin clients sometimes lag behind desktop PCs in terms of extensibility. For example, if a local software utility or set of device drivers are needed in order to support a locally attached peripheral device (e.g. printer, scanner, biometric security device ), the thin client operating system may lack the resources needed to fully integrate the required dependencies (although dependencies can sometimes be added if they can be identified). Modern thin clients address this limitation via port mapping or USB redirection software. However, these methods cannot address all scenarios. Therefore, it
700-425: A third party. Thin client computing is known to simplify the desktop endpoints by reducing the client-side software footprint. With a lightweight, read-only operating system (OS), client-side setup and administration is greatly reduced. Cloud access is the primary role of a thin client which eliminates the need for a large suite of local user applications, data storage, and utilities. This architecture shifts most of
750-404: A very low total cost of ownership , but some of these initial savings can be offset by the need for a more robust cloud infrastructure required on the server side. An alternative to traditional server deployment which spreads out infrastructure costs over time is a cloud-based subscription model known as desktop as a service , which allows IT organizations to outsource the cloud infrastructure to
800-423: Is a connectionless protocol meaning that messages are sent without negotiating a connection and that UDP doesn't keep track of what it has sent. UDP provides checksums for data integrity , and port numbers for addressing different functions at the source and destination of the datagram. It has no handshaking dialogues and thus exposes the user's program to any unreliability of the underlying network; there
850-414: Is a collection of computer servers , usually maintained by an organization to supply server functionality far beyond the capability of a single machine. They often consist of thousands of computers which require a large amount of power to run and to keep cool. At the optimum performance level, a server farm has enormous financial and environmental costs. They often include backup servers that can take over
900-415: Is a common use of a server farm; such a system is sometimes collectively referred to as a web farm . Other uses of server farms include scientific simulations (such as computational fluid dynamics ) and the rendering of 3D computer generated imagery (see render farm ). Server farms are increasingly being used instead of or in addition to mainframe computers by large enterprises. In large server farms,
950-431: Is computed over the following fields: Lacking reliability, UDP applications may encounter some packet loss, reordering, errors or duplication. If using UDP, the end-user applications must provide any necessary handshaking such as real-time confirmation that the message has been received. Applications, such as TFTP , may add rudimentary reliability mechanisms into the application layer as needed. If an application requires
1000-403: Is discussed in RFC 1071 : Checksum is the 16-bit ones' complement of the ones' complement sum of a pseudo header of information from the IP header, the UDP header, and the data, padded with zero octets at the end (if necessary) to make a multiple of two octets. In other words, all 16-bit words are summed using ones' complement arithmetic. Add the 16-bit values up. On each addition, if
1050-414: Is documented in RFC 768 . Although UDP provides integrity verification (via checksum ) of the header and payload, it provides no guarantees to the upper layer protocol for message delivery and the UDP layer retains no state of UDP messages once sent. For this reason, UDP sometimes is referred to as Unreliable Datagram Protocol . If transmission reliability is desired, it must be implemented in
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#17327722350711100-414: Is generally transmitted using UDP. Real-time video and audio streaming protocols are designed to handle occasional lost packets, so only slight degradation in quality occurs, rather than large delays if lost packets were retransmitted. Because both TCP and UDP run over the same network, in the mid-2000s a few businesses found that an increase in UDP traffic from these real-time applications slightly hindered
1150-538: Is good practice to perform validation tests of locally attached peripherals in advance to ensure compatibility. Further, in large distributed desktop environments, printers are often networked, negating the need for device drivers on every desktop. While running local productivity applications goes beyond the normal scope of a thin client, it is sometimes needed in rare use cases. License restrictions that apply to thin clients can sometimes prevent them from supporting these applications. Local storage constraints may also limit
1200-531: Is identified by the port number , a 16-bit integer value, allowing for port numbers between 0 and 65535. Port 0 is reserved but is a permissible source port value if the sending process does not expect messages in response. The Internet Assigned Numbers Authority (IANA) has divided port numbers into three ranges. Port numbers 0 through 1023 are used for common, well-known services. On Unix -like operating systems , using one of these ports requires superuser operating permission. Port numbers 1024 through 49151 are
1250-460: Is little or no user data to be compromised. Modern thin clients have come a long way to meet the demands of today's graphical computing needs. New generations of low energy chipset and central processing unit (CPU) combinations improve processing power and graphical capabilities. To minimize latency of high resolution video sent across the network, some host software stacks leverage multimedia redirection (MMR) techniques to offload video rendering to
1300-404: Is no guarantee of delivery, ordering, or duplicate protection. If error-correction facilities are needed at the network interface level, an application may instead use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP) which are designed for this purpose. UDP is suitable for purposes where error checking and correction are either not necessary or are performed in
1350-463: Is not required at the receiver, because all 0s and all 1s are equal to zero in 1's complement arithmetic. The differences between IPv4 and IPv6 are in the pseudo header used to compute the checksum, and that the checksum is not optional in IPv6. Under specific conditions, a UDP application using IPv6 is allowed to use a zero UDP zero-checksum mode with a tunnel protocol. When UDP runs over IPv4,
1400-402: The registered ports used for IANA-registered services. Ports 49152 through 65535 are dynamic ports that are not officially designated for any specific service and may be used for any purpose. These may also be used as ephemeral ports , which software running on the host may use to dynamically create communications endpoints as needed. A UDP datagram consists of a datagram header followed by
1450-501: The 2010s, thin clients were not the only desktop devices for general purpose computing that were "thin" – in the sense of having a small form factor and being relatively inexpensive. The nettop form factor for desktop PCs was introduced, and nettops could run full feature Windows or Linux; tablets , tablet-laptop hybrids had also entered the market. However, while there was now little size difference, thin clients retained some key advantages over these competitors, such as not needing
1500-621: The ability to turn off both computer parts, processor parts, and entire computers ( WoL and virtualization ) according to demand without bringing down services. The network connecting the servers in a server farm is also an essential factor in overall performance, especially when running applications that process massive volumes of data. The EEMBC EnergyBench, SPECpower , and the Transaction Processing Performance Council TPC-Energy are benchmarks designed to predict performance per watt in
1550-486: The application; UDP avoids the overhead of such processing in the protocol stack . Time-sensitive applications often use UDP because dropping packets is preferable to waiting for packets delayed due to retransmission , which may not be an option in a real-time system . The protocol was designed by David P. Reed in 1980 and formally defined in RFC 768 . UDP is a simple message-oriented transport layer protocol that
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1600-445: The checksum is computed using a pseudo header that contains some of the same information from the real IPv4 header . The pseudo header is not the real IPv4 header used to send an IP packet, it is used only for the checksum calculation. UDP checksum computation is optional for IPv4. If a checksum is not used it should be set to the value zero. The checksum is calculated over the following fields: As IPv6 has larger addresses and
1650-405: The cost, power consumption (heat, noise and vibrations), making them affordable to own and easy to replace or deploy. Numerous thin clients also use Raspberry Pis . Since thin clients consist of fewer hardware components than a traditional desktop PC, they can operate in more hostile environments . And because they typically don't store critical data locally, risk of theft is minimized because there
1700-437: The critical design parameter for both large and continuous systems tends to be performance per watt rather than cost of peak performance or (peak performance / (unit * initial cost)). Also, for high availability systems that must run 24/7 (unlike supercomputers that can be power-cycled to demand, and also tend to run at much higher utilizations), there is more attention to power-saving features such as variable clock-speed and
1750-410: The data center. Servers must be sized correctly in order to deliver adequate performance to end users. In a cloud-based computing model, the servers can also represent a single point of failure risk. If a server fails, end users lose access to all of the resources supported by that server. This risk can be mitigated by building redundancies, fail-over processes, backups, and load balancing utilities into
1800-419: The desktop device. Video codecs are often embedded on the thin client to support these various multimedia formats. Other host software stacks makes use of User Datagram Protocol (UDP) in order to accelerate fast changing pixel updates required by modern video content. Thin clients typically support local software agents capable of accepting and decoding UDP. Some of the more graphically intense use cases remain
1850-479: The emphasis heavily on graphics – which became obsolete as a distinguishing characteristic in the 1990s as text-only physical terminals themselves became obsolete, and text-only computer systems (a few of which existed in the 1980s) were no longer manufactured. The term "thin client" also conveys better what was then viewed as the fundamental difference: thin clients can be designed with less expensive hardware, because they have reduced computational workloads. By
1900-503: The failure of an individual machine is a commonplace event: large server farms provide redundancy , automatic failover , and rapid reconfiguration of the server cluster. The performance of the largest server farms (thousands of processors and up) is typically limited by the performance of the data center's cooling systems and the total electricity cost rather than by the processors' performance. Computers in server farms run 24/7 and consume large amounts of electricity. For this reason,
1950-613: The functions of primary servers that may fail. Server farms are typically collocated with the network switches and/or routers that enable communication between different parts of the cluster and the cluster's users. Server "farmers" typically mount computers, routers, power supplies and related electronics on 19-inch racks in a server room or data center . Server farms are commonly used for cluster computing . Many modern supercomputers comprise giant server farms of high-speed processors connected by either Ethernet or custom interconnects such as Infiniband or Myrinet . Web hosting
2000-606: The host server or server farm needs to be secured, rather than securing software installed on every endpoint device (although thin clients may still require basic security and strong authentication to prevent unauthorized access). One of the combined benefits of using cloud architecture with thin client desktops is that critical IT assets are centralized for better utilization of resources. Unused memory, bussing lanes, and processor cores within an individual user session, for example, can be leveraged for other active user sessions. The simplicity of thin client hardware and software results in
2050-554: The launch of Oracle 7 . At the time, Oracle wished to differentiate their server-oriented software from Microsoft's desktop-oriented products. Ellison subsequently popularized Negris' buzzword with frequent use in his speeches and interviews about Oracle products. Ellison would go on to be a founding board member of thin client maker Network Computer, Inc (NCI), later renamed Liberate. The term stuck for several reasons. The earlier term "graphical terminal" had been chosen to distinguish such terminals from text-based terminals, and thus put
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2100-496: The performance of applications using TCP such as point of sale , accounting , and database systems (when TCP detects packet loss, it will throttle back its data rate usage). Some VPN systems such as OpenVPN may use UDP and perform error checking at the application level while implementing reliable connections. QUIC is a transport protocol built on top of UDP. QUIC provides a reliable and secure connection. HTTP/3 uses QUIC as opposed to earlier versions of HTTPS which use
2150-785: The primary concerns. The use of TCP would cause jitter if any packets were lost as TCP does not provide subsequent data to the application while it is requesting a re-send of the missing data. Numerous key Internet applications use UDP, including: the Domain Name System (DNS), the Simple Network Management Protocol (SNMP), the Routing Information Protocol (RIP) and the Dynamic Host Configuration Protocol (DHCP). Voice and video traffic
2200-673: The servers can be cheaply vented or used to help heat buildings, thus reducing the energy consumption of conventional heaters. User Datagram Protocol In computer networking , the User Datagram Protocol ( UDP ) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets ) to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths. UDP
2250-730: The servers, roughly another 50 watts is needed to cool them. For this reason, the siting of a server farm can be as important as processor selection in achieving power efficiency. Iceland , which has a cold climate all year as well as cheap and carbon-neutral geothermal electricity supply, is building its first major server farm hosting site. Fibre optic cables are being laid from Iceland to North America and Europe to enable companies there to locate their servers in Iceland. Other countries with favorable conditions, such as Canada, Finland, Sweden and Switzerland, are trying to attract cloud computing data centers. In these countries, heat from
2300-519: The software execution burden from the endpoint to the data center. User assets are centralized for greater visibility. Data recovery and desktop repurposing tasks are also centralized for faster service and greater scalability. While the server must be robust enough to handle several client sessions at once, thin client hardware requirements are minimal compared to that of a traditional PC laptop or desktop. Most thin clients have low-energy processors, flash storage , memory, and no moving parts. This reduces
2350-455: The space required to install large applications or application suites. It is also important to acknowledge that network bandwidth and performance is more critical in any type of cloud-based computing model. IT organizations must ensure that their network can accommodate the number of users that they need to serve. If demand for bandwidth exceeds network limits, it could result in a major loss of end user productivity. A similar risk exists inside
2400-570: The system. Redundancy provides reliable host availability but it can add cost to smaller user populations that lack scale. Popular providers of thin clients include Chip PC Technologies, Dell (acquired Wyse Technology in 2012), HP , ClearCube , IGEL Technology , LG , NComputing , Stratodesk , Samsung Electronics , ThinClient Direct , and ZeeTim . Thin clients have their roots in multi-user systems , traditionally mainframes accessed by some sort of computer terminal . As computer graphics matured, these terminals transitioned from providing
2450-592: The tradition of the multi-user, remote display/input session. Typically, X software is not made available on non-X-based thin clients, although no technical reason for this exclusion would prevent it. Windows NT became capable of multi-user operations primarily through the efforts of Citrix Systems , which repackaged Windows NT 3.51 as the multi-user operating system WinFrame in 1995, launched in coordination with Wyse Technology's Winterm thin client. Microsoft licensed this technology back from Citrix and implemented it into Windows NT 4.0 Terminal Server Edition, under
2500-404: The user's application. A number of UDP's attributes make it especially suited for certain applications. Applications can use datagram sockets to establish host-to-host communications. An application binds a socket to its endpoint of data transmission, which is a combination of an IP address and a port . In this way, UDP provides application multiplexing . A port is a software structure that
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