Thin client - what it is and what it is used with (using WTWare as an example). Informatization and education

As a rule, when we talk about the features of a created program, we mean the language in which it was compiled, as well as the system requirements required to run it. But there are also a number of other, less well-known definitions. One of them is thin clients. What is it and why are they being developed?

What is a thin client?

These are computers or programs that operate as part of a network with a client-server or terminal architecture. However, they work there for a reason. Many data processing tasks are transferred to servers to which thin clients are connected. As an example, consider the browser used to process network applications. To ensure system functionality, a server designed for thin clients is required. Otherwise, the implementation of the idea itself is impossible.

What are they for?

Simply put, a thin client is a full-fledged computer that can load a lightweight operating system and also connect to a terminal server. It is used only to save on software and hardware. An ordinary thin client is a system unit that does not have hard drive, however, there are shortcomings in the hardware required to run the operating system. Thus, the connection of the power supply, manipulator, keyboard, monitor, as well as network cable. In addition, other devices may be present, but use is only possible if they are identified and information about them is transmitted to the terminal server.

It is also worth noting that the required level of software costs is reduced. There is no need to purchase a license for each device. Operating personnel costs are also reduced since only one terminal needs to be administered. In practice, it has been proven that it is quite difficult to harm a thin client. However, this increases the requirements for service personnel. This is especially related to issues of transferring data from one administrator to another. In this case, it is necessary that the intercessor understands everything well, since potentially any problems can harm the entire system. After this, the value of thin clients will be lost.

Main differences between thin and thick clients

What are we talking about when we talk about thick and thin clients? The differences between them are as follows: thick clients are a type of programs that are able to function autonomously on a separate terminal; they do not need a remote server designed to perform their own work efficiently. The thin client was described above.

What is the principle of operation and what types of downloads exist? Information about the job can be described in three points:

1. The thin client is loaded onto the computer using one of the possible sources. The main options you can consider are: LAN, CD, HDD.
2. During download thin client network card The computer gets its own IP address.
3. After completing the swapping of everything that is necessary, a connection to a terminal session with the server specified in the settings is provided through the desktop.

In this case, access may already be given or a password and login may be required. The connection of a thin client due to the local network of the enterprise must be allowed in the server settings. Thus, the principle of operation is already a little clear. The most important step is loading, which all thin clients have.

The following possibilities are worth noting:

1. Download via network. It must have TFTP and DHCP servers running. The computer must have a network card with the BootROM property, or special drivers that emulate it. It is necessary to check the presence of all pointers, obtain settings and load the operating system.
2. Boot the system from DVD\CD\Flash\IDE, preloaded.

Web client

Thin client technology is very popular. Moreover, does the user use it constantly? A greater role must be given to the most common thin clients today. If it's not clear yet, we're talking about browsers. They act as ideal examples of working according to these principles. Separately, the browser is practically useless. However, the possibilities that it opens up for a computer that is connected to the global network are quite great. The device can have a fairly modest resource software, however, having received the required data from remote servers, it is quite possible to count on the development of a multi-purpose object high quality. To do this, it is enough to formulate your own request, and then the required data will be obtained from external sources.

Working in terminal mode

In addition to the cases described above, you need to pay attention to one more hardware feature of the thin client. It includes a special device that differs in design from personal computer. This mechanism does not provide for the presence hard drive, uses a special local operating system. In addition, it does not have special moving parts, is offered in special housings and is completely different passive cooling. Next, it’s worth giving a specific example to clearly see where else a thin client can be used. IN in this case you should consider the 1C program. So, it is based on the work of two parts. One of them is the platform itself, which is necessary for work. The second part is an extension that fulfills individual purposes. However, it is not able to work without a platform.

Protocols used by thin clients It is worth noting the nine most famous types of protocols used in the development of this software. Their list is as follows:

1. X11 – used on Unix systems.
2. Telnet – is a multi-platform protocol. Acts as a bidirectional eight-bit byte-oriented means of communication.
3. SSH – is a multi-platform analogue of Telnet. The main difference is the security of the transmitted information.
4. NX NoMachine is a modified X11 protocol. The main advantage is data compression.
5. Virtual Network Computing is a platform-independent system. Uses a regular client-server protocol application level to gain access to the required computers connected to this program.
6. Independent Computing Architecture - is a rather imperfect method of data transfer. Such a protocol significantly affects the performance and requirements for the systems with which it operates.
7. Remote Desktop Protocol - capable of serving capabilities remote access to the desktop. It is possible to transmit a wide range of information, opening up greater possibilities for using remote devices.
8. SPICE – acts as a protocol designed for data transmission, used comfortably both on a local network and using the Internet. The main features include “software ease”, which makes it possible to quickly exchange information. This is possible due to the simplicity of data transfer processes. In addition, it is possible to work on a wide range of architectures.
9. Various closed protocols developed by programmers from various companies and organizations. They are usually used on the premises of the enterprise for which they were developed. There are many unique parameters including implementation, system requirements, architecture. In this case, the thin client is created for certain enterprises and protocols that operate in the territory.

Implementation examples As an example of a thin client implementation, it is worth giving the following:

Terminal access;
diskless station;
LTSP;
Thinstation.

The use of thin clients makes it possible to increase the speed of updating everything that is necessary for the functioning of the software.

The technical field is replete with a wide variety of terms that can be difficult to understand. Often, even using some kind of program, a person may not understand what a particular word means. For example, many people try to understand what a thin client is?

The Russian name for this concept was formed by simple translation English phrase, thin client. This word means some a device or program that may have a client-server or terminal. It is to them that the bulk of information processing tasks are transferred.

One simple example can be given. For the average user, a thin client is a regular browser through which a person works with web applications. In this case, another name is sometimes used - P2P client, if it accesses some other network nodes.

What is a thin client?

Externally, a thin client often looks like system unit without hard drive. It contains only those elements without which it will be impossible to start the operating system. Also, for example, a mouse and keyboard are connected to this kind of computer. There are other components, but only those listed above are necessary.

How it works:

• There are three main types with which the client is loaded. These are HDD, LAN and CD.
• In the case of a LAN, the connected computer receives a specific IP address before the client is fully turned on.
• In other cases, the address is obtained during the download process.
• When the download is complete, the thin client will use rdesktop to start a session according to the server settings.

Most often, such technology is used in organizations that need to perform a large volume of some similar tasks. This is often associated with the processing of databases, such as various catalogs and libraries. Thus, thin clients are used in stores, pharmacy chains, and bank terminals also operate with their help.

To operate a thin client, they usually use a fairly standard terminal server. Often they turn to the OS Windows Server, although Linux is also in use and Solaris is a little less common. Regardless of the brand, the server must have a high degree of performance and reliability.

Why do you need a thin client?

There are several main reasons why people turn to thin clients. Most of them are related to the desire to save. If the owner of an enterprise already has a powerful terminal server and clients configured for it, then he can significantly save on the purchase of a computer and components. All he needs to do is purchase the cheapest possible assembly, even a very old one, and simply connect it to the server.

• The second aspect of savings is the absence of the need to purchase any special software, such as various drivers. All that is required is a working licensed terminal server.
• The same applies to administration costs. If any problems occur with the thin client, they will be associated exclusively with the server, and by the way, it breaks down extremely rarely.
• Even ordinary electricity is saved, since the thin client consumes much less energy than full-fledged workstations.
• Unification is another advantage of a thin client. It gives everyone the same set of software and eliminates the need to configure each computer separately. Configuration also takes place centrally.
• Such equipment does not make noise and does not emit much heat, which is a priority in terms of environmental impact.

If you create such a system once, then the network can easily be expanded at any time with minimal effort. You will be able to connect as many new personal computers as you like. Finally, the absence of any local media reduces the likelihood of information leakage.

After the release of the eighth version of the 1C utility, it became possible to operate in thin client mode. This option has a lot of advantages, but has limitations in terms of capabilities. First of all, this mode is used to increase mobility. For example, a boss, having gone somewhere far away, can use any Internet network to log into a thin client and study the data available there.

• This reduces the load on the connection. It is used in a narrow direction, only for data transmission, so it is not necessary to have a very strong connection throughput.
• Using this mode in the program does not require powerful software. Serious resources are not needed, everything works quite well on weak PCs.
• All this significantly reduces the company's costs.

From the point of view of use in the 1C program, there are a couple of negative aspects of the thin client. The key one is the need to have a powerful server. The rest are purely related to ease of use. Limited functionality does not allow you to use some aspects of the program, such as the Configurator mode.

In general, the advantages of the thin client significantly outweigh its disadvantages. It facilitates many work processes and reduces company costs. If she already has a suitable server or terminal, and they, accordingly, know very well what a thin client is, then practically no problems arise at all.

Video instructions

Workplaces in the office. The client communicates with the server via terminal access and receives all data for work in the same way. A typical example of a thin client is a computer with a browser that works with remote applications.

For the most part, a simple low-power computer without a hard drive running specialized versions of the operating system (for example, Linux WTWare) is used as a thin client. Otherwise, the thin client is not much different from the standard one workstation– there is a system unit, display, input devices, network access (via LAN or using a modem).

The principle of operation of a thin client provides for a continuous terminal connection with a special server, which not only stores the working data of each user, but also runs working programs with which the client interacts. The client can be downloaded using external media(for example, CD or Flash drives), as well as via a LAN network if the network card supports the BootRom option.

Options for implementing thin clients in the office

Most often, a thin client is a computer with reduced functionality - without a hard drive or other storage device. Such workstations can be purchased ready-made or assembled yourself. To start, you also need to set up a terminal server - it is to it that clients will be connected, and on it basic calculations will be performed, as well as data will be stored. Previously, in offices they preferred to install a physical terminal server, but today, with the development of cloud technologies, it is increasingly being moved to the cloud. The role of a terminal server can be either a separate powerful computer with the appropriate OS and running application programs, or an entire cluster, if the needs for information processing are large, as is the number of simultaneous connections.

To set up an office based on thin clients, you need to achieve uninterrupted access to the network, because without a direct connection between work machines and the terminal computer, work will be completely impossible - autonomous thin clients are most often inoperable. Quality provider cloud solutions with high uptime usually completely solves this problem.

Main advantages of terminal access

Initially, the principle of terminal access and thin clients was developed for one single purpose - to save money. This infrastructure model allows for significant savings on equipment - the cost of workstations is much lower compared to full-fledged PCs for work. In addition, there is an opportunity to save on software - there is no need to buy licenses for each workstation, you can buy one license and install it on the server. The cost of system administration is also reduced, since maintenance is mainly required only for the terminal server.

Over time, with the development of technology and the decentralization of work, other advantages of this solution became obvious:

• the ability to work remotely from anywhere in the world with an Internet connection;
• simplicity and scalability – the configuration of the working environment can be easily changed without affecting performance;
• saving all data in one place guarantees its safety and accessibility for each employee;
• security and data protection - in most thin client implementations, the user does not have the ability to locally save or copy working files and data. To this you can add traffic encryption and the ability to completely disable the server if necessary.

This solution has practically no disadvantages. The only thing is the requirement for a constantly working and serviceable network connection, however, today this is not a difficulty.

Where are thin clients used?

The simplicity and convenience that terminal access provides quickly won a significant number of fans in various fields of activity:

• increased security and closedness of the system have been actively used in banking sector– for example, working with ERP systems, online banking;
• the convenience of teamwork, the safety of work results and the speed of access to software have made thin clients indispensable in large offices - here terminal interaction with office packages, 1C accounting system, various additional programs, Internet access, corporate mail etc.;
• In the educational environment, terminal clients are also used - they allow you to effectively organize educational process, reduce the cost of computer lab equipment, simplify remote education and testing;
• The technology has also been used in medicine - safe storage data on the clinic’s servers and convenient access to the database allows you to quickly resolve emerging issues and make management more efficient;
• Warehouses and especially large warehouse complexes are increasingly being transferred to terminal access with control and accounting programs uploaded to the cloud.

In addition, potential areas for the development of thin clients include systems for interaction between government and the population (“ e-government", housing and communal services authorities, online document management, etc.).

Solutions for organizing a remote office from Tucha

Trying to keep up with current trends in the market, we offer a ready-made package for organizing your own terminal access in the office -. This is a completely turnkey solution for implementing infrastructure with access through thin clients. The server has everything you need - high level uptime, ease of scaling, secure data transmission channel and others. We also offer assistance in migrating applications and give you the opportunity to install your own software. We guarantee high uptime, data safety, the ability to create backup copies And quick recovery of them. Connection is possible using any device - PC, thin clients, mobile devices.

Try it and you will never go back to your old work organization again.

Starting with version 8.2, the 1C program gained the ability to work in thin client mode, which has limited functionality. Despite the fact that quite a lot of time has passed since the update was released, a large number of users still do not fully understand why this innovation is necessary, in what situations it is effective to use and what is its difference. In this material we will talk in detail about what the 1C thin client is, its advantages and disadvantages, as well as how to work with it.

What is a “thin client”?

In order to understand the functionality of this client program, you need to figure out why it is called “thin”. The answer to this question is quite simple and is that this mode The work is very limited in its capabilities compared to the “thick” version.

The application's "thin client" has a more limited set of built-in language types, which is intended exclusively for transferring data and changing it. Everything related to working with the database is executed on the server in this case. Using this version of the application, a managed 1C interface is developed, which allows you to optimize the company's work.

1C “thin clients” are capable of receiving ready-made data via a web connection, which has already been prepared in advance on the server side.

In addition, the use of this type of application is possible using one of three technologies:

• Via the web (using an Internet connection);
• Via TCP/IP protocol (client-server type);
• Directly with the database.

Internet connection

The Thin Client has the ability to interact with the 1C: Enterprise program using a web connection to the Internet. In this case, work occurs with a specially configured web server using the http data transfer protocol. However, the web server itself works with the 1C: Enterprise program via the TCP/IP protocol or directly.

Important: you must use one of the following systems as web servers:

• Apache;

Client-server connection

In this case, thin clients connect to servers directly using the TCP/IP data transfer protocol.

Direct database connection

In this case, there is direct interaction between the client and the application database. To organize this work scheme, a special environment is created on the computer on which the client is installed, which is perceived as a server from the program’s point of view. In order to organize it, you need to:

• Download the required server files to a computer;
• Load application configuration.

Benefits of a thin client

If we put the process technology aside and move on to the immediate advantages that using this version of the 1C client provides, we can highlight several serious advantages. These include:

• Mobility;
• Reducing the load on the communication channel;
• Minimum system requirements;
• Reducing company costs.

Mobility

A hardware “thin client” allows the user to be anywhere in the world, as long as there is an Internet connection. For example, suppose that the head of a department is on vacation abroad. In order to make any important decision, he needs to familiarize himself with the latest reporting data. Full version applications require a local network connection, which is why in this case a “thin client” comes to the rescue. It allows you to work with the database with a regular Internet connection.

Another example. Sometimes, when making transactions in a branch that does not have a connection to the local network, for example, in a company warehouse, it is necessary to download data from the warehouse database for subsequent loading into the accounting department.

Of course, such manipulations take time and cause inconvenience. “Thin clients” are precisely used to simplify such tasks. If you have a web connection, you can easily transfer data to a common 1C database directly from the warehouse.

In addition, “thin clients” use a network channel exclusively for data transfer. The full version of the application also uses it to transmit service data necessary for the operation of the software, which reduces the useful bandwidth of the channel.

Thus, “thin clients” allow you to work in the 1C program where there is no web connection with good bandwidth.

Low system requirements

The situation is similar with the system requirements of the program. To run the full version you need more than powerful computers, since the application uses the system's processor and RAM. “Thin clients” 1C are much less demanding on the resources of a personal computer. This is what allows it to be used even on weak systems.

Reducing company costs

This point follows from all the previous ones. Due to the fact that the development of a managed interface allows you to optimize the workflow, save time and resources of the company, this leads to a reduction in the company’s overall costs for accounting.

Disadvantages of the thin client

Of course, any medal has reverse side. The "thin client" also has some inconveniences and limitations, which cannot be ignored. These include:

• Requirement of a powerful server;
• Limited functionality;
• Unusual interface.

Requires a powerful server

In the event that a large number of “thin clients” interact with the main server via a web connection, it is enough to rely on it heavy load, which imposes certain technical requirements. However, using the full version of the program does not load much less, so this disadvantage is very relative.

Limited functionality

As already stated above, light version The application has very limited functionality. For example, it is not possible to work in the “Configurator” mode.

Interface

This disadvantage Over time and with the release of updates, it gradually fades away, but at first many companies refused to use “thin clients” or tried to avoid it precisely because the application interface was extremely inconvenient and very different from the full version.

Part one: Some lyrics

The following text by the author does not pretend to be the ultimate truth and should not be used to judge the average statistical level of IT infrastructure in small companies in our vast country. The article was written based on conversations with numerous familiar IT people (mostly at the “student” and “just out of college” level), who began their careers as IT specialists in small companies.

Let's imagine an average office of a small trading company from an IT point of view:

• several dozen weak computers for the secretary, managers, accounting department and, of course, the main Boss;
• one, two or three machines performing the following roles:
  • windows domain controller (there are often cases when there is not even a domain in the company’s network, and all computers work in a peer-to-peer network);
  • file server;
  • mail server (instead, external free mail servers are sometimes used, ranging from mail.yandex.ru and gmail.com to ten-dollar hosting for N mailboxes);
  • http proxy for filtering access to external resources and logging “where anyone goes” (often missing)
  • router/firewall on the border with the external network to restrict access to the outside and vice versa (often any SOHO router is used as a border router entry level priced up to $100, it also acts as a DHCP server (for dynamically distributing IP addresses to employee workstations);
  • other things, the list of which can be quite large;
• several printers, often connected locally to employee workstations and shared over the network using standard Windows tools (alternatively, printers can be networked initially or connected through hardware print servers).
• in advanced cases - one terminal server (under Windows) for accounting (1C runs on it and there is also a database thereof, and accountants, connecting to the terminal server via standard means Windows (remote desktop), they work with it on a terminal server (locally), which, firstly, gives more convenience, and secondly, speeds up the work of 1C itself (usually 1C with the database is installed on the computer of one of the accountants, and the rest connect to it from their computers, working with a database shared over the network).

All this equipment is connected into a single local network through one/several cheap 100Mbit switches. And this works in a single NT/Active directory domain (although there are options for peer-to-peer workstations without any domains).

All Windows machines usually have some kind of antivirus installed (although there are exceptions). Often there are non-network versions of these programs (the same Avast), although, again, in more advanced (from an IT point of view) offices, there are network versions of antiviruses with centralized management and updating of anti-virus databases.

The above situations vary from case to case, since the configuration of the network, hardware and software is influenced by both the knowledge/skills/desires (and, importantly, laziness) of the system administrator(s), and the understanding of the authorities (represented by the main Boss) " what exactly is this our system administrator engaged when everything is already working perfectly” (from the latter it follows how much money is allocated for IT equipment and the salary of the future specialist). If little money is allocated (and this is usually the case - managers of trading companies are usually far from IT and have little understanding of what is happening there), then the Enikey employee who has gained enough knowledge leaves for another company. Another student takes the place of the one who left and everything repeats all over again.

I think it is unnecessary to say that in such offices the system administration department consists of one person who also combines the installation/maintenance engineer office network, the system administrator as such (i.e. the very person who is responsible for the performance of the server park at the software and hardware levels and the introduction of new functionality) and the Enikeishik - the “errand boy” who is involved in solving problems for users, wiping mice, changing printer cartridges and similar things.

As a result, small companies often have a fairly diverse fleet of user machines ranging from pentium2/128Mb ram/5Gb hdd to P4 Celeron/1Gb ram/80Gb hdd. On all machines, of course, Windows (98, 2000 and XP Home/Pro) and different versions software (the machines were installed at different times). It comes to the point that the anti-virus software on machines is also from different manufacturers.

And it falls to the difficult lot of the system administrator (and part-time Enikey specialist) to support this entire zoo day and night. But iron sometimes breaks:

• the fans begin to buzz obnoxiously (they need to be cleaned and lubricated or replaced with new ones);
• power supplies fail;
• hard drives are crumbling;
• network cards (both built into the motherboard and external ones stop working and require replacement);
• the rest of the iron usually flies much less often, but nevertheless flies too

If the hard drive fails (or motherboard computer), the operating system on the restored machine often has to be rearranged from scratch in this or a very similar sequence:

• install Windows;
• put necessary drivers(the entire fleet of hardware is different - haven’t you forgotten?), having previously determined the model of the motherboard in this machine and downloaded it from the Internet latest versions drivers or by finding the ones you need on your file server;
• enter the machine into the domain (if it is configured);
• install the necessary software (office, browser, mail client, total commanders, ICQ, jabbers, punto switchers and the like) - in case domain Active Directory part of the software can be installed automatically, but not everyone has it configured, and not everyone knows its capabilities;
• install antivirus;
• plus additional dances with a tambourine, individual for specific network each organization around a new workstation;

After successfully completing all the steps (this procedure takes about two hours), we report to the Boss that the employee’s workplace has been saved and he can start working.

The happy owner of the restored computer sits down at his workplace, after which it turns out that (since the domain profiles were not movable or there was no domain at all, the “my documents” link led to local disk C:, and about the fact that everything important needs to be saved on network drive- on the server, the employee forgot):

• I had a folder here with important documents - where is it?
• I also saved photos from Turkey there, is it possible to restore them?
• there were many important shortcuts and a hundred more documents on the desktop - where did they go?
• in favorites (this is about bookmarks in the browser), my favorite sites are no longer there - where can I look for them now? and so on…

Sound familiar? It’s good if it’s not the hard drive that crashed, but just the motherboard. Or some of the information on the crumbled disk can be restored. But all these procedures take working hours system administrator, which could be spent with much greater benefit playing a network shooter or... studying IPv6 - after all, everyone is already switching to it and will switch very soon, addresses in the IPv4 space have already run out for about five years :)

As a result, supporting the IT infrastructure of a small company for a system administrator turns, for the most part, into supporting the performance of user workstations, namely:

• reinstall Windows;
• configure all the necessary software on the new machine;
• restore everything that was lost;
• install new programs for those in need;
• carry out preventative maintenance on the case (vacuum dust in the system unit);

And in the remaining time (if the system administrator is not very lazy), you need to try to learn something new, upgrade the software on the server (servers) and put a new network service into operation. Those. There is just no time left for basic duties (exactly what a system administrator should do most of the time).

How to get out of this vicious circle?

One of the options for solving the problem described above is to abandon “thick” workstations (where this can be done) and switch to .

A “thick” workstation means any computer with an installed OS, which processes the majority of user information. Those. the browser, office and everything else is executed locally on the user’s workstation, the system unit of which hums under his desk or somewhere nearby.

You need to understand that the requirements of modern operating systems (not necessarily Windows) keep pace with modern hardware - in other words, for relatively comfortable work in Windows XP, an old (but fully functional and relatively powerful) Celeron class machine 800Mgz/128Mb Ram/10Gb HDD can not enough. It is, of course, possible to work under a modern OS on such hardware, but this operating system and applications will slow down quite often, if only because of the small amount of on-board memory and the old (read slow) hard drive.

A thin client, in short, can be defined as a diskless computer, the work of which consists only of connecting to a remote server and displaying information received from the server on the screen. Typically such a server is called a terminal server or terminal server. All processing of user information occurs on it (to which many, although not an infinite number, of thin clients can be connected simultaneously).

Typically, thin clients are made on the basis of weak (and, accordingly, low-power) hardware - often this is a single motherboard on which everything is integrated. The processor and memory can also be tightly soldered to the motherboard. Some thin clients have a flash disk (inserted into the IDE connector of the motherboard), on which a specialized OS (WinCE or others) is flashed.

Comparison of the Clientron U700 thin client with a standard workstation chassis.

As a result, when you turn on the thin client (they are also called terminals), the OS is loaded from the built-in flash disk (usually it takes less than 30 seconds to load), after which a dialog for connecting to the terminal server appears on the screen. Some of these clients can only connect to Windows Terminal Server or Citrix Metaframe, others can also connect to terminal servers of other operating systems. In any case, the price of such solutions also includes the price of a license for WindowsCE flashed onto the built-in flash drive. We talked about similar solutions earlier:

• Windows terminal
• Thin client
• Windows terminal

Of course, other companies have similar solutions. Including without a built-in OS (for which, in the case Microsoft Windows CE, you need to pay extra, and the flash drive is a penny, but it’s worth it).

Terminal clients without a built-in flash disk, when turned on, download the required OS image over the network, after which they spend the same couple of tens of seconds loading. After which they are ready to work, which means displaying a menu with a list of terminal servers to connect to or automatically connecting to one of the hard-coded terminal servers (depending on the settings) - the user will only have to enter a login and password. After entering it correctly, he gets into his session on the terminal server and can start working.

The undoubted advantages of terminal solutions on specialized thin clients or proper self-assembled computers:

• lack of a hard drive (which gets hot and breaks);
• lack of fans (only radiators are installed on the processor and power supply, which are enough to dissipate the heat generated during operation);
• low power consumption;
• theoretical low cost (when self-assembling, you can select very cheap components, since hardware performance is not required; but manufacturers will ask twice as much for specialized thin clients)
• minimal time costs for maintenance (if such a piece of hardware breaks down, it is enough to disconnect the broken one and connect a spare one for five minutes; and this is the minimum downtime for an employee’s workplace, as well as the minimum time spent on fixing the breakdown of the system administrator)
• all software for users’ work is configured centrally on one (two/three/…) terminal servers this is much simpler than maintaining a zoo of software on “thick” employee workstations

Don’t forget about user data: the terminal does not store anything locally (all user data is located on remote servers). As a result, it’s easy to set up automatic backups of everything and, if something happens, restore an “accidentally deleted” document.

In general, there are a lot of advantages, but there are also disadvantages:

• if the network fails, employees’ workstations “turn into a pumpkin” (and employees on “thick” clients can continue to type a document, for example, in OpenOffice);
• if the terminal server fails, the employees’ workplaces again “turn into a pumpkin” (but this can be solved by installing several - for example, two - terminal servers; if one of them fails, the second one will replace it, or the employees will simply reconnect to the second server manually)
• thin clients are not suitable for everyone: for example, people who constantly watch videos or work actively with graphics (in Photoshop) or do magazine layout are better off doing this on a local “thick” client (but thin clients are great for most other employees who need only a browser with the Internet, mail, creating and editing documents in Openoffice and working with 1C).

The last disadvantage, which we will not consider here, is the licensing policy (if not to say rip-off) on the part of Microsoft. Working on a terminal server running the OS of this well-known company requires a large number of different licenses:

• Windows Server license
• CAL (Client Access License) licenses for connecting to a Windows server and their number must be no less than the number of clients connecting to the server (usually the Windows server already includes a certain number of such licenses from five and above)
• licenses for working with a terminal server (their number must also be equal to the number of connected clients)

Don’t forget about separate licenses for all software used (for example, Microsoft Office) in an amount equal to the number of clients connecting to the server. If client licenses for Microsoft Office can still be bypassed by abandoning this product and installing a replacement in the form of, for example, OpenOffice, then getting rid of the terminal server itself in the form of Windows 2000/2003 TS is somewhat more difficult :) Although this is possible in some cases .

There is, however, one more “minus” (besides the fear of new things) that often stops implementation similar decisions- for some reason, many people think that these thin clients need to be bought (and they are not very cheap - from $200 and above). What should we do with the entire fleet of existing computers?

It is to answer the last question that this series of articles was written. It will cover thin client software.

This small, but with many capabilities and, importantly, OpenSource software, allows you to turn almost any ancient computer into thin clients. The minimum hardware described on its home site for the hardware used is a Pentium 100Mhz and 16Mb of RAM. Oh yes, a hard/flash drive is also not needed - when computers are turned on, they can download the thin client image (this is about twenty megabytes) over the network (although it is also possible to install the Thinstation client on a hard or usb disk). In our age operating systems, happily gobbling up gigabytes of disk space after installation, that's impressive, isn't it?

Thinstation is based on Linux, but to use it you do not need Linux knowledge as such - just install dhcp and tftp servers on your network and configure them accordingly (both of these servers are included in Windows products Server). Thus, even on a network where they don’t know anything other than Windows, using the Thinstation client will not cause any difficulties.

Thinstation can work with the following terminal servers:

• Microsoft Windows server via RDP or via nxclient (Windows NT4TSE, W2k Server, W2k3 Server or Windows XP in single-user mode);
• Citrix servers via ICA protocol (on MS Windows, SUN Solaris and IBM AIX servers);
• Tarantella Servers
• *nix-like servers using X11 protocol;
• connection to VNC servers (tightVNC);
• connection to SSH and Telnet servers;

In order to boot Thinstation over the network, the computer only needs a built-in or external network card that supports the PXE standard (there are other options, but, for example, all network cards built into the motherboard work using this protocol).

PXE stands for Pre-boot eXecution Environment. This standard was first implemented by Intel. The first sign of the presence of a PXE BIOS on board the built-in network card is the “Enable Boot ROM” item next to the network card activation item in the BIOS. If the built-in network card does not support booting over the network (or is absent altogether), you can use any external network card with the “Boot ROM” option (this issue will be discussed in detail below).

Now let's take a quick look at the process of downloading the Thinstation client over the network.

• The network card via the PXE protocol requests the DHCP server for the following information: IP address, subnet mask, gateway, as well as the IP address of the TFTP server (on which the images are located, in this case, ThinStation) and the name of the image that it will try to download.
• The DHCP server returns the requested information (noting that the IP address issued to the client is occupied by such and such a client)
• The client connects to the TFTP server whose IP address was just given to it and downloads the PXE boot loader file from it (the name of which was again given to it by the DHCP server)
• The downloaded PXE loader is executed and, in turn, downloads a configuration file from the TFTP server, which contains the names of the Linux kernel files vmlinuz and the image file system initrd. These files are downloaded and control is transferred to the Linux kernel
• After unpacking and loading Linux kernels with the mounted image of the file system, Thinstation again accesses the TFTP server to download the configuration files it needs (among other things, the addresses of the terminal servers to which you need to connect are written there), after which it launches the desired terminal client (in our case it will be rdesktop) and expects the user to enter his login and password to connect.

At first glance, the described scheme looks complicated. But in fact, setting it up takes half an hour to an hour and in the future it works completely autonomously. Booting the thin client from the moment of the first request to the network via PXE (this moment coincides with the moment the OS starts loading from the hard drive) takes 20...30 seconds.

As noted above, Thinstation can work with different terminal servers. But in the upcoming articles, as the easiest thing to implement (but I remind you once again about purchasing many client licenses necessary for official work), we will only consider the combination of Thinstation with Microsoft Terminal Server.

First, we need to have a configured terminal server from Microsoft. This server can operate both as part of a domain (in this case it is more convenient to manage user accounts - they are shared, especially if there are several terminal servers on the network), and outside the domain - in a peer-to-peer network. The second case differs from the first in that the necessary users will have to be created locally on each server and the current lists of users and their rights will have to be synchronized manually.

The second point of our program will be setting up DHCP and TFTP servers. The first one is in charge of the dynamic distribution of IP addresses for workstations, and also reports from which IP address (from which tftp server) and what file name the computer needs to download as a boot image of the thin client. And the second tftp server actually delivers the thin client images and configuration files for them too. These settings can be either global (for all diskless terminals on the network) or local for certain groups of machines or single thin clients.

Both of these services can be raised as part of Windows servers(by launching and configuring the corresponding services), and individual daemons as part of a *nix server we will look at this using the example of a server with Gentoo Linux installed.

And the third point is setting up client machines transferring them to boot over the network and considering standard pitfalls.

But more about this in the next articles of our series.