9. Client-Server Thin-client Architecture

A school may elect to install a Client-Server based system. This means that you have a very smart and fast server that serves out to the machines on the network, everything that they need. The computers on the network, when in the client server mode, don't process data at all other than sending each keystroke and command to the server. This requires both a very fast server with lots of RAM and also a very fast network. However it also means that you do not have to upgrade your machines in the classroom. The machines in the classroom can be Pentium 100's or less but will operate at the specifications of the server.

In practice what results is the computers in the classroom doing some stand alone activity and some in the client-server mode.

The two main contenders for supplying the software required for this type of network are Citrix Metaframe and Windows Terminal Server. Both software packages sit on the server and although the Citrix option is a bit more expensive it does process data more efficiently. The limitation is that you cannot move high bandwidth data around the network. This means that in general, multimedia and sound are out. BUT for general office applications and internet HTML based application there is no problem. You need to predetermine the future use of the computers before opting for this approach. It would be ideal for the suite of computers used for "office" type applications. Other advantages of the Citrix option are the ability to dial into the school computer from home and use the school resources and the speed of the school server from your limited and possibly much older home PC.

Citrix licences are concurrent which means that if you purchase 50 licenses then only 50 people can access the server at one time. However if students are working on their own work using the power of the computer in front of them then 50 licenses may be sufficient for 70 students, depending on the work being done. You can change from working in client mode to working as a stand alone computer quickly and simply.