Point-to-Point is a form of communication that provides a direct path from one fixed point to another. A point-to-point wide area network WAN consists of two end nodes connected by a leased line.
In a typical configuration, a router on the network is connected using a serial transmission interface such as V. An identical setup is configured at the remote customer premises. Users can collaborate by communicating over their LAN. This collaboration may be facilitated by groupware that runs on a LAN. Users can access other networks within a firm or outside of it via bridges and routers.
There are two principal LAN designs :. Peer-to-peer - peripherals are located at terminals and system administration is largely left up to the users. Server-based networks - shared resources are placed a dedicated server that manage a given resource on behalf of user workstations sharing the resource file server, printer server, gateway, optical disk server. Most of the servers are dedicated to their task; using them as workstations degrades the performance of the net.
A company with a large number of telephones from 50 to over 10, often elects to own a computer-based private branch exchange PBX , an electronic switchboard that interconnects its telephones and provides connections to the public network. Characteristics of a PBX:. Gives a company control over the usage of its telephone system and offers a variety of features, such as call forwarding or voice messaging.
Maybe employed as a switch for data communications. Many newer PBXs use digital technology, eliminating the need for modems, and perform conversions needed to ensure connectivity between various equipment and telecommunications links. Easy to connect a new workstation to the net. Speeds of PBX-based networks are limited. An important current development in organizational computing is downsizing - moving from platforms based on mainframes and minicomputers to a microcomputing environment.
The processing of a given application is split up among a number of clients - serving individual users - and one or more servers - providing access to databases and doing most of the computing.
Main objective of a client is to provide a graphical user interface to a user. Main objective of a server is to provide shared services to clients. Two-Tier Architecture. Three-Tier Architecture. Characteristics of Two-Tier Architecture: [Figure 7. Client performs presentation services. It displays the GUI and runs the program that determines what happens when the user selects a menu option.
Server manages the accesses to the database. Clients send remote procedure calls to activate specific applications logic on a server. Characteristics of Three-Tier Architecture: [Figure 7. An application server runs most of the application logic, with the user workstation responsible for the display at the front end and the database server providing database servers at the back end. Objective is to distribute application so as to reduce the overall hardware costs while minimizing the network traffic.
Is attractive in terms of their acquisition price as related to their performance. Is moving computing control out of the data centers and into the end-user areas. Software is complex, and is expensive to maintain. Generate significant traffic on the firm's backbone network that connects clients and servers.
Wide area networks are the fundamental infrastructure of organizational computing. These long-distance telecommunications networks employ a variety of equipment so that the expensive links may be used effectively. The offerings of common carriers and of providers of value-added services may be combined with private networks to create an overall organizational network.
WANs include equipment that controls message transfer and makes it possible to share the links among a number of transfers. A WAN has a powerful host computer. The host runs a system program, called a telecommunications monitor, which processes incoming messages, passing them to the appropriate application programs, and accepts outgoing messages from the applications in order to transmit them into the network.
Front-End Processor. Relieves the host computer of most of the tasks involved in network control. Under the control of its own software, the front-end processor accepts messages coming from the network and routes outgoing messages to their destinations. It performs the necessary code conversions, encrypts and decrypts secure messages, and performs error checking so that the host deals with Aclean messages.
Cluster Controller. Manages several terminals, connecting them to a single telecommunications link, and performs communication tasks for them, such as screen formatting, code conversion, and error checking. A cluster controller may also allow the terminals to share a high-speed printer and may handle electronic mail among the cluster terminals.
Combines the data that terminals send to it over local low-speed links into a single stream. This stream is then transmitted over a high-speed telecommunications channel and is split by another multiplexor on the opposite end of the channel. Combines transmission from several slower terminals that operate in a burst mode into a single transmission stream that requires a link of lower speed than the sum of the speeds of all the terminals combined.
A concentrator stores messages from terminals and forwards them when warranted. Establishes connections between nodes that need to communicate. Include a variety of dumb terminals, with no processing capacity and intelligent terminals with processing capacity, such as personal computers.
Some network facilities are owned by user organizations, others can be leased by them, or simply used on a pay-as-you-go basis. Among the typical facilities owned by user firms are workstations, host computers, and front-end processors. The essential providers of telecommunications links and services are common carriers and the vendors of enhanced services on value-added networks. These include:. Providers of value-added networks.
Private lines and private networks. Are companies licensed by a country's government to provide telecommunications services to the public. The vast majority of common carriers provide telephone service. These carriers offer the use of a wide-area telecommunications infrastructure, that is, facilities for the transmission of voice and data messages. Common carriers offer a service called virtual private network where a user firm can purchase guaranteed access to facilities with specified capabilities, such as transmission speed and access points.
Providers of Value-Added Networks. Value-added vendors lease facilities from the common carriers and provide telecommunications services to their own customers. These vendors add value to the basic infrastructure furnished by the common carrier. The value-added networks VAN provided by the vendors furnish services over and above those provided by common carriers.
Private Lines and Private Networks. Instead of using a service that has to be shared with others, a firm may lease its own private lines or entire networks from carriers. This can have economic advantages as compared with VAN use, as well as provide faster and more secure communications.
The Internet has changed the face of individual and organizational computing. Driven by the possibilities offered by the Internet and the Web, electronic commerce is expanding its reach. Present and Future of the Internet. The Internet is the global network of computer networks without a centralized control that has become the contemporary Ainformation highway. Characteristics of the Internet:. It is run in a decentralized fashion by a number of voluntary organizations, the principal of which is the Internet Society.
It is a medium of communication, a source of information, and a developing means of electronic commerce. A major obstacle to its development has become the limited capacity of the links interconnecting the networks.
Facilities for Communication and Information Access. The Internet provides several essential facilities that organizations can use for internal as well as interorganizational information sharing and communication. The principal categories of Internet use include:.
Electronic mail E-mail facilitates quick exchange of information and ideas, and is the Internet facility in widest use. E-mail can be used for one-to-one communications or to participate in larger communications forums newsgroups.
Information Access:. The Internet provides access to the largest organized loosely repository of information on earth: the collection of electronic documents stored on sites all over the world.
The main problem is finding the information. To help with this problem Web search engines have been developed. The World Wide Web or simply, the Web is an information service available over the Internet, providing access to distributed electronic documents via hyper links.
Characteristics of the Web:. Grew out of the need of scientists who wanted to share information and to collaborate from geographically dispersed locations. The Web is a collection of electronic sites stored on many thousands of servers all over the world. Each site consists of a home page and often other pages stored with it.
Pages contain hyperlinks to related pages, usually stored on other sites. Access to the Web is through a client program, known as a browser. The browser sends out for the needed page into the Internet, interprets the formatting directions on the retrieved page, and displays the page accordingly on the screen.
A search engine is a Web facility that maintains its own information about the documents available on the Web. Electronic commerce is sharing business information, maintaining business relationships, and conducting business transactions by means of telecommunications networks.
In simple words, electronic commerce is doing business electronically, replacing most of the paper and telephone work with computer-mediated information and transaction exchange. The Internet, and the Web in particular, are emerging as the principal means for this new way of doing business. Some potential uses include:. Establishing an electronic site on the Web to promote your business. On-line marketplaces. Advertising at frequented Web sites. Establishing newsgroups.
One of the biggest drawbacks for the use of the Internet for conducting electronic commerce is the lack of financial security. The framework of electronic commerce is summarized in three levels:. They can work on a small battery for many years, as long as they are put into deep sleep to optimize power consumption. Based on this nomenclature, three types of terminal equipment can be distinguished: — class A, — class B, — class C. Class A devices are devices that consume the least energy compared to other classes.
This is due to the fact that they can only receive information Downlink after sending their own data Uplink. Class A devices are suitable for transmitting data at a specific interval, e. Class B nodes Class B allow to receive more messages than in the case of class A. This reduces message delays, but at the cost of lowering the energy efficiency of the device.
Finally, Class C devices Class C can still receive messages, except when they are sending data themselves. It is therefore the least energy efficient class and typically requires the use of a permanent power source for operation. Gateways are also known as modems and access points. These messages are often converted into packets that can be sent over traditional IP networks.
The gateway is therefore connected to a network server to which it forwards all messages. The gateways are transparent by design and have limited computing power. All complex operations and intelligent algorithms are implemented on a web server. Depending on the application, gateways can be divided into two types: — for use inside buildings, examples of which are devices such as The Things Gateway, — for outdoor use, such as Kerlink IoT Station and LoRiX One.
All messages sent through gateways are forwarded to the web server. It is here that more complicated processes related to data processing take place. It is primarily responsible for:.
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