In today's fast growing community, workers are now spread around the world in branch offices, customer sites, homes, hotels and many other places. The need for organizations to access their applications and data whenever and whereever they wanted is increasing. Numerous innovative computing devices and technologies have been invented to meet the market demand, including servers, notebooks, Windows-based terminals, client/server architecture and recently 'thin' client/server technology. This white paper is going to illustrate the differences between FlexSystem's Ultra Thin-Client and alternative products available in the market.

What is Client/Server?
Client Server is a computational architecture that involves client processes requesting service from server processes.

Traditional Client/Server
In the traditional client/server architecture, most of the business logic, as well as the Graphical User Interface (GUI) generation, are executed on the client side. It requires each personal computer (PC) at the client level to be equipped with powerful processor, plenty memory and disk space to sun large applications. Apart from the hardware requirement, these applications need to be installed and maintained on an ongoing basis. Whenever there is an upgrade to the application code, it needs to be distributed to each client PC as well, imply that the consumption of network bandwidth is much higher. Therefore, the application upgrade can be expensive, time-consuming and hard to manage.

Thin Client/Server
Applications designed in the Thin-Client/Server Architecture are built in a way that almost none of the business logic resides on the client. Aside from possible user interface requirements, the client logic will be concentrated on the server or host system, while the client acts as a very "lightweight/thin" process that only needs to display the screen and accept input through the user interface. Thus, minimal processing power is required, and application upgrades are not necessary at the client level. Normally, Thin-Client applications require less network bandwidth than the traditional client/server model, so that remote client able to access the information via Internet/Intranet.

Mainly, there are two kinds of end product under Thin/Client/Server Architecture:
- Web based client/server
- Terminal emulation products

Web Based Client/Server
Web Based Client/Server computing uses web browser to access and manipulate information, stored in a centrally controlled Database Management System (DBMS), in the internet, WBCS generated HyperText Mark-up Language (HTML) pages on the fly to the browser for access the information via the www.

How It Works

1.	A user runs a web browser on an Internet-enabled PC. The browser sends a request for a particular HTML text file over the Internet to an Hypertext Transfer Protocal (HTTP) web server. The Web browser responds by sending the requested file to browser.
2.	The web browser sends displays the file according to the HTML text and provides options for the user to choose further action after reading the document.
3.	The browser sends the web server a request for a specific document that corresponds to the option that the user selected. The request might include parameters, such as entry data, which are specific to the action the user chose.
4.	The web server interprets the request as a command to run a particular server-side process.
5.	The server-side process logs into the DBMS and executes a data manipulation or query command that corresponds to the action chosen by the user.
6.	The command might select records based on certain search criteria or even change values for a certain record, depending on the action the user chose. The server-side process merges the results of the DBMS with a pre-defined set of HTML tags, thus building an HTML page on the fly.
7.	The server-side process passed the new HTML page to the web server.
8.	The web server sends the new HTML page to the web browser to show the result for the end user.

The important aspect in the WBCS is that the HTML page sent by the web server to the web browser is generated dynamically upon request. IT has a mot of overhead for presenting, sending and manipulating the HTML pages over the Internet, therefore it is difficult to build an efficient large scale application system.


Shortcoming of Web-Based Client/Server

Slow Internet Speed
WBCS works, but works slowly. The application speed in Intranet does not show any drastic different when compared with those to tradition client/server.

Among many reasons for the Internet speed problem is that HTTP passes individual files back and forth between machines over telecommunication lines, so it takes time for the web browser to interpret and display each file to the user. To improve the speed of WBCS application on the Internet, eliminate unnecessary graphics from WBCS applications, pay for faster Internet access methods, and deploy multiple web servers and application instances can be the solutions to disperse network traffic.

Eventually, the enormous growth in demand for a better, faster Internet will bring about solutions for the speed problem. Ironically, grown in demand also plays a major role in the slow down. It stands to reason that until the growth f Internet access demands slows down enough for supply to catch up, speed will continue to be a problem for WBCS applications.

Limitation of HTML
In its current state, WBCS applications cannot provide users with the highly interactive interfaces of applications constructed with other GUI development tools. Applications designed with GUI tools can be customized to complete transactions from a single screen. Although WBCS application still so the job right, complex transactions may require the user to navigate several simple screens rather than use a single comprehensive screen.

To the web browser, everything entered in HTML from is text, which means a server-side process must perform data validation after the entry has already been submitted from the browser. If there is a validation error, the server-side process must send an HTML page back to the browser to inform the user about the error. Thus the efficiency will be affected since it does not have a client-side process perform the validation before the data is submitted to the server.

More Complex Security Issues
Since the nature of the Internet is open to public, security of WBCS data is a serious issue to consider. Extra steps must be taken to ensure that private information remains secure.


Terminal Services
Terminal Services revolves around Multi-User Windows NT/2000. It allows multiple concurrent users to log on and run applications in separate Windows sessions on a NT/2000 server. The session is delivered over a network to a client device where the user interface is display.

Application execution, data processing and data storage occur on the server. Applications and user desktops are displayed via "thin client" software, which acts as a terminal emulator in much the same way as X-11 does for UNIX.


Shortcoming of Terminal Services

High Bandwidth Consumption
The concept of Terminal Services is to replicate a desktop between the server and the client. All information related to the operation on desktop is transferred between the client and the server. These include the entire desktop/application screen, mouse movements, mouse clicks etc.. Thus the bandwidth requirement by each client is very high.

High Server Resources Required
Further to the replication of desktop which lead to a high consumption of bandwidth, it also leads to a high consumption on server resources, resulting in less concurrent user host in each server. Normally a terminal services server can only support 20 concurrent users effectively.


FlexSystem Ultra Thin-Client
Ultra Thin-Client Technology is solely developed by FlexSystem, which combines the latest multi-tier application server technology with effective compression and communication algorithm, to help the enterprise running its operations via Internet/Intranet in the most effective and cost saving manner. Directly embedded into ERP solutions, FlexSystem Ultra Thin-Client utilizes most of the best practices to handle different kinds of client/server communication needs, to guarantee the lowest bandwidth consumption and 10 times better performance compared with other Thin-Client products on the market.

Bandwidth Consumption
Under client/server architecture, system performance depends a lot on bandwidth consumption. The large amount of data being transmitted, the higher the bandwidth required in a given period of time.

Terminal services product has been developed in a way that any activities on the workstation (including non-command activities, such as cursor movements and page up/down) are transmitted from the workstation to the server. Once transmitted, a screen refresh will travel back to the workstation to update the display unit. Due to the excessive amount of data transmitted back and forth between the client and the server, heavy network traffic and slow system processing result.

Hardware Resources
Generic terminal emulation tools, which have to be executed several layers of applications to mimic a thin-client environment, consume a tremendous amount of server resources (i.e. CPU and RAM). Comparatively, ultra Thin-Client is built on top of FlexSystem's proprietary application server technology to cater for enterprise date computation. It requires 80% less of server resources and supports 5 times the concurrent client sessions, maximizing the server resources effectively.

Compared with others, FlexSystem Ultra Thin-Client Technology only requires the transmission of relevant information (such as action and data) between the workstation and the server, so that the date to be transmitted is minimized and user can enjoy the speedy performance even in a narrow bandwidth connection (for example 9.6kps mobile communication). In case for the broadband is available, multiple concurrent clients can share a single connection, thus effectively lowering the communication cost by over 70% than traditional thin-client products.

Scalability
Ultra Thin-Client's date cache layer is specially designed for the handling the massive data transaction. Its cache management algorithm has been fine-tuned to make the most effective usage of server memory and processing power, delivering the fastest performance and providing more concurrent access from a single server. As the server reached its fully capacity, it also support multiple application server, allowing enough room to accommodate the needs associated with the business grows.

Security
User is given the access to share directory in order to update the date in the date server under the client/server environment. Such drive mapping practice exposes the risk to endanger the data security because any user can simply log on to a local or remote client PC to gain access to all the crucial information in the PC, as well as in the network. But in case of Ultra Thin-Client, the access points are effectively controller. The client program should be installed in the client terminal to access the application server, marking the obvious difference with Terminal Services and Browser-Based Applications which use common client programs.

Virus and Hacker Protection
A virus is a piece of programming code inserted into other programming to case some unexpected undesirable event. Under the Terminal Services environment, any infected file, the host server will also be infected. And since all other workstations are connected to the host server, sharing the resources as well as the applications, the whole network will be infected within a very short period of time.

In the case of Browser-Based Applications, system might also be infected through virus web components such as virus Active X objects.

On the other hand, there is lower chance of virus attacks while using FlexSystem Ultra Thin-Client because workstations are connected to the server via its proprietary communication methods such that the server and the client workstations are totally isolated. If a single client is infected, the virus cannot infect the host server and other client workstations.

Moreover in hacker prevention, the URL or IP address of the application server is known to all client terminals for Browser-Based Applications. Although the application may have Authentication process, it is not 100% safe. Hence the high level of security is guaranteed if the server address is not disclosed to users like FlexSystem Ultra Thin-Client.