Ch. 6
Understanding DSS Architecture, Networking and Security Issues

The fundamental purpose of computer networks is to provide access to shared resources, including storage for decision support data and information. One type of network for providing shared resources is a Local Area Network (LAN). A LAN has several primary components:

• A network interconnection and hubs (for example, copper wire, fiber optic cable, infrared, or radio).
• Network Interface Circuitry (NIC) in the individual personal computers connected to the network.
• The shared resources like a database server, each with their own NIC connected to the network.
• Software on a personal computer that uses the NIC to access the shared resources. This software is typically arranged to present the appearance to the rest of the operating system that these resources are directly connected.
• Software on the shared resource that coordinates with the software on the individual machines to provide access to the shared resources for users. This type of software is called a multi-user operating system. UNIX is a common operating system for DSS, but Windows NT is used in some architectures and for implementing some DSS packages.

The most common network design is for the server in a local area network (LAN) to be the same sort of personal computer hardware as the individual personal computers on the network. In this case, the operating system is called a "network operating system" or NOS to emphasize the difference from the single-user operating system of the personal computer. Novell Netware is an example of this approach. A NOS is an operating system that manages network resources. The NOS is like a traffic cop, controlling the exchange and flow of files, electronic mail, and print jobs. It manages multiple requests concurrently and provides the security needed in a multi-user environment.

A Local Area Network (LAN) is a communications network that serves users within a confined geographical area. It is made up of servers, workstations, a network operating system and a communications link. A Wide Area Network (WAN) is a much larger network than a LAN and all machines are not directly connected. A group of LANs are often connected and form a WAN. LANs and WANs can be directly connected to the global Internet.