第4章 Computer Network Knowledge
4.1 Computer Networking Concepts
4.2 The OSI Reference Model
4.3 Internet Overview
4.4 Internet Security
4.5 E-commerce
4.1 Computer Networking Concepts
? Computer network can be used for numerous services, both for companies and for individuals.
? Networks can be divided up into LANs, MANs, WANs, and Internet works, each with their own characteristics, technologies, speeds, and niches.
? Network software consists of protocols, or rules by which processes can communicate.
? Network establishes communication among computers. This system is especially helpful when people work on different place.
Local Area Networks (LANs)
? A local area networks, or LAN, is a communication network that is privately owned and that covers a limited geographic area such as an office, a building, or a group of building.
? The LAN consists of a communication channel that connects either a series of computer terminals together with a minicomputer or, more commonly, a group of personal computers to one another.
? Two common applications of local area networks are hardware resource sharing and information resource sharing.
Wide Area Networks (WANs)
? A wide area network, or WAN, is geographic in scope (as opposed to local) and uses telephone lines, microwaves, satellites, or a combination of communication channels.
? Telephone company deregulation has encouraged a number of computers of companies to build their own wide area networks.
Network Configuration
? The configuration, or physical layout, of the equipment in a communication network is called topology.
? Communication networks are usually configured in one or a combination of three patterns.
? These configurations are star, bus, and ring networks.
Star Network
? A star network contains a central computer and one or more terminals or personal computers connected to it, forming a star.
? A star network configuration is often used when the central computer contains all the data required to process the input from the terminals, Such as an airline reservation system.
? A star network can be relatively efficient, and close control can be kept over the data processed on the network.
Bus Network
? When a bus network is used, all the devices in the network are connected to a single cable.
? Information is transmitted in either direction from any one personal computer to another.
? An advantage of the bus network is that devices can be attached or detached from the network at any point without disturbing the rest of the network.
Ring Network
? A ring network does not use a centralized host computer. Rather, a circle of computers communicate with one another.
? A ring network can be useful when the processing is not done at a central site, but at local sites.
? An advantage of a ring network is that less cable is usually needed and therefore network cabling costs are lower.
Connecting Networks
? Sometimes you might want to connect separate network. You do this by using gateways and bridges.
? A gateway is a combination of hardware and software that allows users on one network to access the resources on a different type of network.
? A bridge is a combination of hardware and software that is used to connect similar networks.
4.3 Internet Overview
Web Service
? The short-form of a Web Services definition is: “A set of standards that allow applications to talk to each other over the net.”
? The “Services” part of Web Services is indicative of the service-oriented nature of application communications.
? A service can combine multiple back-end application functions into what is known as a “composite application interface”.
? Web Service interfaces are defined using XML in the form of a “schema” that describes the request and response data formats, types, and relationships.
? Web Services technology supports increased operational efficiencies and improved service by allowing multiple applications to interoperate.
? Now that we know a little more about Web Services, lets look at the two different scenarios mentioned above: intra-enterprise, where internal applications are involved; and inter-enterprise, where applications of different trading partners are involved.
How To Use Internet
? Most people connect to the Internet by using network connection or Internet service provider (ISP).
? An ISP supplies a service number that you can dial from your computer to log on the Internet server.
? With the communication tools included in Windows 2000, you can use your computer to send e-mail, handle phone calls, send a fax, or conduct a meeting with a video conference.
? With Internet Explorer and an Internet connection, you can search for and view information on the World Wide Web.
? You can use Phone Dialer to place telephone calls or participate in video conference calls from your computer.
? The Windows 2000 Telephony API (TAPI) allows you to configure dialing rules for all telephony applications.
4.5 E-commerce
? E-commerce is doing business through electronic media.
? It means using simple, fast and low-cost electronic communications to transact, without face-to-face meeting between the two parties of the transaction.
? Electronic commerce is featured by these characters: fairness and freedom, high efficiency, globalization, virtualization, interactivity, autonomy, personalized service.
? Electronic commerce will change the environment in which enterprises compete with each other and reduce costs which would otherwise be high in traditional market structure.
? To ensure security of electronic commerce, an electronic certification center should be established.
The features of Electronic Commerce
? Space-time concept will change.
? The nature of market and the behavior of consumers change.
? Corporate credit and brand become treasured resources.
? Structure of enterprises will change from “pyramid” type to “flattened” type.
? Business mode in enterprises will change.
? Higher requirement of workers’ quality and technique.
? Material flow will be more important in electronic commerce than in usual commerce.
? New recognition of information resource and attention resource.
E-Commerce Strategies
? The Web is adding new dimensions to conventional business practice and creating new types of business strategies.
? As computer network facilitates information exchange in a speedy and inexpensive way, Internet now penetrates into almost every corner of the world.
? Small and medium sized enterprises (SMEs) can forge global relationships with their trading partners everywhere in the world.
? Businesses can sell goods to customers outside traditional markets, explore new markets and realize business opportunities more easily.
? Companies must take advantage of customer information in their commerce models.
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