8. Downsides

Even though the Client-Server type of network has many advantages, there are some disadvantages that you should be aware of.

The cost of this type of network is relatively high up front, not only must you purchase the server hardware, but most server software is very expensive, especially for larger networks since some software companies charge more for each client computer that will connect to the main server (although there are cheaper alternatives). Once the network is in place however, it is relatively easy to justify the cost since the overall cost to maintain the network becomes less expensive.

Another downside to consider is the possibility of the main server having problems. How fast must you have the network working again? If you need 24x7 operability, you should allow in your budget a second "redundant" server, so if the main server goes down, the redundant server will step in and provide services until the primary server is back up again. An experienced administrator should be able to setup redundant servers that will assume control of failing servers without user intervention.

9. Conclusion

The Client-Server network model provides important services to the network safely and securely, it also allows the convenience of allowing the users to work on their own workstation machine. However, this network model can be very expensive, not only because the software can be expensive, but you also must provide adequate hardware for both the servers and the individual workstation machines, which can become very expensive with revolving hardware updates.

If you have the funds to implement this type of network, the return on the investment is great, and you will have the knowledge that your network is well secured and archived.

10. Application-Server Network

The final network type that will be covered is the Application Server based Networks, sometimes called Terminal Server based. The idea behind this type of network is that you basically have one high-end server or mainframe, and all the network clients are "dumb terminals", meaning that none of the processing is actually done on the terminals, instead the only job the terminals have is to provide input and show the display on the monitor.

Most people equate application servers to the very old text-only terminals with no pointing devices. Today application servers are very modern, and most people running on a "dumb terminal" will think they are working on a modern standalone computer.

11. Example

Each floor has its own Application Server running a version of Linux. Each application server has basic user applications, such as Internet Browser, Word Processor, Spreadsheet Program, Email Application, Image Manipulation Program, as well as all the basic applications you should find on a computer. Each Application Server serves applications to 20 different terminals, which are older donated computers. Each terminal has the ability to run all of the above applications, print to any of the printers on each floor and has access to the main card catalog through a web-based interface.

If one of the Application Servers goes down, the network is configured so that the terminals will log into one of the other floors servers until the computer is repaired. If a terminal goes down, a replacement terminal can be installed with no downtime for the entire network, with no information loss.

All the Application Servers also share a single /home directory from a separate File Server, which allows the library the ability to offer an individual login name, email account and individual storage for a small charge. Along with the login name, email account and storage, the patron also has the ability to access any files he may have saved on the file server through a secure FTP server.