Internet
The internet, which is the largest computer network in the world, is actually a network of networks. These interconnected networks exchange information seamlessly by the same open, nonproprietary standards and protocols. They are connected via high-speed, long-distance, backbone networks.
The internet is a new communications dimension-an electronic, virtual world where time and space have almost no meaning. The internet is an open and environment that is remarkable free of censorship, a tribute to its roots in the academic and research communities.
Evolution of internet
The internet began as one network, called the ARPANET. The ARPNET was a 1969 U.S government experiment in packet-switched networking. ARPA was the Department of defense Advanced Research Projects Agency.
The ARPANET originally linked a largely technical audience composed of the military, government agencies, and academic researchers and scientists. The original ARPANET split in to two networks in the early 1980’s the ARPANET and Milnet, but connection between the two networks allowed communication to continue.
The infrastructure of the internet
Although internet began as a government project, currently the U.S government pays only a small percentage of internet costs. Commercial communication companies now largely provide the physical network backbone of the internet.
The U.S government continues to contribute some funds to essential administrative process, such as standards development and domain name system (DNS), through contracts with private organization that perform these functions. The National science Foundation NSF) also pays for certain high-performance potions of the network backbone.
Network service providers, such as UUNET, an MCI WORLDCOM COMPANY, GTE Internetworking, sprint, and others, supply the internet these and other smaller inter service provider may be large backbone providers; in other cases, it will be smaller (often local) company connecting to the larger network service provider. Both backbone and access providers are referred to as Internet Service Providers (ISPs).
Backbone providers must be connected to one another and to access providers, and this is done over backbone networks. The various the various backbone networks that makes up the Internet transmit information to another on a reciprocal basis, meaning that each carrier aggress to transport traffic originating on another carrier’s network.
Operations of the internet:
The set of rule used to send and receive packets from one machine to another over the internet is known as the Internet Protocol (IP). The IP and TCP protocols re so commonly used together that are referred to as the TCP/IP protocols used by the internet applications.
The internet, a packet-switching network, breaks each message in to packets. Each packet contains the address of the sending and receiving machines, as well as sequencing information about relative to other packets in the message.
Each packet can travel independently across various network interconnections. Therefore, packets may utilize different paths across the Internet and arrive out of sequence. When all packets arrive at the receiving computer, they are reassembles in to complete message.
Address on the internet
Each computer on the internet as an assigned address, called the IP address that uniquely identifies it from the other computer. The IP numbers have four parts, separated by dots. For example, the IP address of one computer may be 135.62.128.91. Most computers also have names which are easier to people to remember than IP addresses, these names are derived from a naming system called the domain name system.
Domains names consist of multiple parts, separated by dots, and are translated from right to left. For example, consider the name software.ibm.computer. “Computer is the name of the top-level specification or the zone. The right most part of the Internet name is the top-level specification. “Computer” indicates that this is a commercial site.
Accessing the Internet
There are three main ways to connect to the Internet. These methods include connecting via a LAN server, connecting via SLP/PPP, or connecting via an online service.
Connect via LAN server:
This approach requires the user’s computer to have specialized software called a communications stack, which provides a set of communication protocols that perform the complete functions of the seven layers of the OSI communications mode.
Connect via serial Internet protocol/point to point protocol (SLIP/PPP):
This approach requires a modem, standard communication software, and an online information service account with an Internet service Provider.
Services provided by the internet
The internet provides three major types of service: communications, information retrieval and World Wide Web. Communication services include electronic mail, USENET newsgroup, LISTSERVs , chatting, Telnet, Internet Telephony, and Internet Fax. Information retrieval services include gophers, Archie, File transfer protocol (FTP) and Veronica. The World Wide Web, with such great importance for electronic commerce.
Communication services
The communication services available on the internet are revolutionizing both the personal and business communication. A tremendous variety of data can be accessed through the Internet.
Electronic mail (e-mail):
The internet is the most important e-mail system in the world because it connects so many people and organizations. E-mail is an application that allows an electronic message to be sent between individuals through telephone wires or over wireless networks. E-mail is not limited to simple text messages. Users can embed sound and images in their messages, and attach files that contain text documents, spreadsheets, graph, or executable programs.
USENET is a protocol that delineates how groups of messages can be stored in and sent between computers. Following the USENET protocol, users send e-mail server to read messages or have the computer automatically download messages to be read at the user’s convenience.
Chatting
Chatting allows two or more people who are simultaneously connected to the internet to hold live (real-time), interactive, written conversions. Internet relay chat (IRC) is a general chat program for the Internet. Chat groups are divided in two channels; each assigned its own topic of conversion.
Telnet
Telnet allows users to be on one computer while doing work on another. Telnet is the protocol that establishes an error-free link between the two computers. Users can log on to their office computers while travelling or from their homes.
Internet Telephony
Internet vendors are providing products that emulate traditional public switched telephone network (PSTN) applications. Internet telephony lets users talk across the internet to any personal computer equipped to receive the call-even around the world-for the price of only the internet connection.
Telnet fax
The use of the internet for real-time fax transmission for emerging as an application that may signal a shift of traditional analog communications from the telephone companies to the packet-switched Internet. This application is useful because faxes can send long distance at local telephone rates, and delivery can be guaranteed through store and forward mechanisms.
Streaming Audio and video
Streaming allows Internet users to see and hear data as it is transmitted from the host server instead of waiting until the entire file is downloading.
Streaming audio enables the broadcast of radio programs, music, press conferences, speeches and news programs over the internet. In the future, streaming audio and Internet use will overlap and complement one another.
Information retrieval allows users to access through the Internet thousands of huge library catalogs that are online, as well as thousands of databases that have been nonprofit organizations. In addition, many users download free download free, high quality software made available by developers over Internet.
Information retrieval services
File Transfer protocol (FTP)
Ftp enables people to access a remote computer and retrieve file from it. After users have on to the remote computer, they can search the directions that are accessible to FTP, looking for the files they want to retrieve.
Archie
Archie is a tool that allows users to search the file at FTP sites. It regularly monitors hundreds of FTP sites and updates databases (called an Archie server) on software, documents, and data files available for downloading. If users click on a listing from an Archie server, it will take them to another computer system where relevant files are stored.
Gophers
Most files and digital information that are accessible through FTP are also available through gophers. A gopher is a computer client tool that enables users to locate information stored on internet gopher servers through a series of hierarchical menus. Each gopher server contains its own system of menus listing subject-matter topics, local files and other relevant gopher sites.
Veronica
Veronica (very easy Rodent – Oriented Net wide Index to computer Achieving provides the capabilities of searching for text that appears in menus. When the user enters a keyword, veronica will search through thousands of gopher sites to find titles containing that keyword.
The World Wide Web
The internet functions as the transport mechanism and the World Wide Web(called the Web, WWW or W3) is an application that uses those transport functions. Other applications also run on the Internet, with e-mail being the most widely used.
The Web is a system with universally accepted standards for storing retrieving, formatting, and displaying information via client/server architecture. The Web handles all types of digital information, including text, hypermedia, graphics, and sound.
It uses graphical user interfaces, so it is very easy to use. The technology underlying the World Wide Web was created by Timothy Berners-Lee, who in 1989 proposed a global network of hypertext documents that would allow hysics researchers to work together.
Offering information through the Web requires establishing a home page which is a text and graphical screen display that usually welcomes the users and explains the organization that has established the page.
All the pages of a particular company or individual are known as a Web site. Web pages provides a way to contact the organization or the individual. The person in charge of an organization’s Web site is called Webmaster.
To access a Website, the user must specify a uniform resource locator (URL), which points to the address of specific resources on the Web. For instance, the URL for Microsoft is http://www.microsoft.com HTTP stands for hypertext transport protocol, which is the communications standard used to transfer pages across the WWW portion of the internet. HTTP defines how messages are formatted and transmitted and what actions Web servers and browsers should take in response to various commands. WWW.microsoft.com is the domain name identifying the Web server storing the websites.
Browsers
Users primarily access the Web through software applications called browsers. At a minimum, a browser is capable of communicating via HTTP, managing HTML, displaying certain types, such as GIF (Graphical Interchange Format) and JPEG (Joint Photographic Experts Group) for graphics and Microsoft windows WAN for sound.
The Mosaic browser provided a graphical font end that enables users to point-and-click their way across the Web, a process called surfing. Web browsers became a means of universal access because they deliver the same interface on any operating system under which they run-windows, Windows NT, OS/2, MacOS, or UNIX.
Search engines
Search engines are programs that return a list of Web sites or pages (designed by URLs) that match user-selected criteria. To use one of the publicly available search sites, the user navigates to the search engine’s site and types in the subject of the search.
Search engines for numbers of Web pages, such as those that attempt to cover the entire Internet, do so by maintain databases that model the web’s structures. Though a combination of information – trolling robot that collect information automatically about Web pages and developer registration, search engines select a large number of Web pages and developer registration, search engines select a large number of Web pages and developer registration, search engines select a large number of Web pages and developer registration, search engines select a large number of Web sites to be indexed. Their database is then populated with information about the contents of each page deemed useful.
Search engines select pages for inclusion in their databases in two primary ways. Web crawlers traverse the Web automatically, collecting index data on one of two search principles: depths first, which follows only the links that are deemed relevant to a topic, or breath first, which follows only the links that are deemed relevant to a topic, or breadth first, which collects the entire network of links form a given starting point regardless of the page contents. Web Crawlers are variously called spiders, ants, robots, bots, and agents.
Registration is allowed by most search sits. Web developers can register in a number of their sites or pages by submitting a form. This process enables developers to ensure that their sites eventually will be included in the search index.
Metasearch engines automatically enter search engines in to a number of other search engines and return the results. Examples of Metasearch sites include all4one Met crawler, and starting point.
Push technology now makes it possible to automatically supply information to users by means of a process running on either the user’s desktop or a network server. With millions of Web sites available for browsing, the only way to guarantee that users certain content is to end or “push” it to them. Push client packages typically are given away free, and the companies that publish them rely on advertising for revenue.
Information filters are automated methods of sorting relevant from irrelevant information. These filters help people access information with more precision; that is, they help people reduce information overload. As the information available over the Internet continues to grow, users increasingly need to narrow the content through which they wish to search.
A more active method of filtering information uses intelligent agents. The goal of agents is to create applications that automatically carry out tasks for users without their intervention, other than configuration and updating with new request.
The number of publications, traditional and electronic, available online continue to increase. In digital format, publication is easily amendable to efficient or automated clipping to use of a clipping services.
HTML & its Enhancements
Enhancements and variations of HTML make possible desirable new layout and design features on Web pages. For example, cascading styles sheets (CSCs) are enhancements to HTML that add pages layout feature to Web documents. A CSS acts as a template that defines the appearance or styles (such as size, color, and font) of an element of a Web page.
Dynamic HTML (DHTML) is a set of extensions of HTML that allows Web pages to be updated in response to actions taken by the user, without the need to reconnect to the Web server to download a new version of the page.
Extensible Markup language (XML) is another method for describing the makeup of different types of documents and a data format for structures document interchange on the web. XML supports Unicode, thus providing support for most of world’s written languages. In addition XML is much better than HTML at drawing data from Heterogeneous data sources and displaying that data in a consistent format.
Voice markup language (VoxML), lets users request data through realvoice request; users do not have to push any touch – tone numbers on the phone. Once requested, the voice commands are translated in to Web requests and the response is returned to the user as common speech.
Virtual reality modeling language (VRML) is used to create three dimensional worlds through which users can navigate within Web browsers using a mouse or other device. VRML applications include virtual business or shopping districts, special interest communities and entertainment arcades.