Unit 6

Internet and www

Introduction to internet and its applications

Internet History:

The US department of Defence developed the first version of Internet during 1970s to allow quick communication among researchers working on the department projects in about 30 locations. The department also saw as a way to continue communications among these important defence sites in the event of a worldwide catastrophe such as nuclear attack. Since these projects were funded by the department‘s Advanced Research Projects Agency(ARPA), the Network was originally called ARPAnet.

In the 1980‘s just as Desktop computers were becoming common, the National Science Foundation funded a high speed connection among University centre based on the ARPAnet structure. • By connecting their individual network, Universities could communicate and exchange information in the same way. However, these new connections had an additional, unexpected benefit. • A person accessing a university network from home or school could also get access to any site connected to that network. • This is how the Internet was born. It is also called as information super highway or cyberspace.

WWW History:

 English scientist Tim Berners-Lee invented the World Wide Web in 1989. He wrote the first web browser in 1990 while employed at CERN near Geneva, Switzerland. The browser was released outside CERN in 1991, first to other research institutions starting in January 1991 and then to the general public in August 1991. The World Wide Web has been central to the development of the Information Age and is the primary tool billions of people use to interact on the Internet.

Web resources may be any type of downloaded media, but web pages are hypertext media that have been formatted in Hypertext Markup Language (HTML). Such formatting allows for embedded hyperlinks that contain URLs and permit users to navigate to other web resources. In addition to text, web pages may contain references to images, video, audio, and software components which are displayed in the user's web browser as coherent pages of multimedia content.

Internet Definition:

The internet is the largest computer network in the world, connecting millions of computers. A network is a group of two or more computer systems linked together.

Internet Applications:

1.    The World-Wide Web (WWW) :

The World Wide Web (WWW), commonly known as the Web, is an information system where documents and other web resources are identified by Uniform Resource Locators (URLs, such as https://www.example.com/), which may be interlinked by hypertext, and are accessible over the Internet, The resources of the WWW are transferred via the Hypertext Transfer Protocol (HTTP) and may be accessed by users by a software application called a web browser and are published by a software application called a web server.

2.   Electronic Mail (E-Mail) :

 • The transmission of messages over communications networks.

 • It is a fast and efficient way to communicate with friends or colleagues.

 • You can communicate with one person at a time or thousands; you can receive and       send files and other information.

 • Basic email functions: – send and receive mail messages – save your messages in a       file – print mail messages – reply to mail messages – attach a file to a mail message.

 • The email address has three parts: – a user name – an "at" sign (@) – the address of       the user's mail server

 • Example Harris@ftms.edu.my

i.                 Email Client

• An email client is a computer program used to manage a user's email. • Popular email clients include Microsoft Outlook, Pegasus Mail, Mozilla's Thunderbird, and Apple Inc.'s Mail.

ii.               Web-based mail

• Is an e-mail service intended to be primarily accessed via a web browser.

• Very popular webmail providers: – Gmail – Yahoo! Mail – Hotmail • Web mail is popular as it allows you to send or receive e-mail from anywhere.

3.   File Transfer Protocol (FTP) :

• The protocol for exchanging files over the Internet.

• Used for moving files between two hosts on a TCP/IP network.

• FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server.

• To do FTP, a user invokes one of two commands: – get - the command for transferring a file from another server to your own computer. – put - the command for moving a file from your computer to another one.

4.   Search Engine:

• A search engine is designed to search for information on the internet. • Search engine presents the search results in the form of a search results list.

• The search results can be web pages, images, videos, and other type of files.

• Example: – Google – Bing

5.   Chatting :

• Chatting is the other method for Internet conversation. • It enables people connected anywhere on the Internet to join in live discussions. • Chat sessions allow many users to join in the same free-form conversation.

Examples:

• MSN Messenger • Yahoo Messenger • IRC • Pidgin

6.   Video Conferencing:

 • A videoconference or video conference is a set of interactive telecommunication technologies which allow two or more locations to interact via two-way video and audio transmissions simultaneously.

The other components required for a videoconferencing system include:

• Video input and output

• Audio input and output

• Data transfer

7.   E-Commerce:

• Electronic commerce or E-Commerce consists of the buying and selling of products or services over electronic systems such as the Internet and other computer networks.

• It includes the entire online process of developing, marketing, selling, delivering, servicing and paying for products and services.

Some common applications related to electronic commerce are the following:

• Domestic and international payment systems

• Group buying

• Automated online assistants

• Online shopping and order tracking

• Online banking

• Shopping cart software

• Electronic tickets.

Client Server Technology

A client-server network is designed for end-users, called clients, to access resources such as files, songs, video collections, or some other service from a central computer called a server.

Client/ Server technology is a means for separating the functions of an application into two or more distinct parts.

Client/ server describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. The client presents and manipulates data on the desktop computer.

The server acts like a mainframe to store and retrieve protected data. It is network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.

ISP Defination with example:

An Internet service provider (ISP) is a company that provides customers with Internet access. Data may be transmitted using several technologies, including dial-up, DSL, cable modem, wireless or dedicated high-speed interconnects.

Typically, ISPs also provide their customers with the ability to communicate with one another by providing Internet email accounts, usually with numerous email addresses at the customer’s discretion. Other services, such as telephone and television services, may be provided as well. The services and service combinations may be unique to each ISP.

An Internet service provider is also known as an Internet access provider (IAP).

Example: Nepal Telecom, NCELL, Worldlink, Techminds, web surfer,Classic Tech etc.

Domain Name server:

Domain Name Servers (DNS) are the Internet's equivalent of a phone book. They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses. This is necessary because, although domain names are easy for people to remember, computers or machines, access websites based on IP addresses.

Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6).

Internet Address:

An Internet address uniquely identifies a node on the Internet.  Internet address may also refer to the name or IP of a Web site (URL). The term Internet address can also represent someone's e-mail address.

For example: Any address used to identify a place or resource on the Internet, such as a URL, an IP address, or a domain name.

Like: www.tu.edu.np

Internet vs Intranet vs Extranet

Types of (Internet/communication) Protocol

1.     Transmission Control Protocol (TCP): TCP is a popular communication protocol which is used for communicating over a network. It divides any message into series of packets that are sent from source to destination and there it gets reassembled at the destination.

2.     Internet Protocol (IP): IP is designed explicitly as addressing protocol. It is mostly used with TCP. The IP addresses in packets help in routing them through different nodes in a network until it reaches the destination system. TCP/IP is the most popular protocol connecting the networks.

3.     User Datagram Protocol (UDP): UDP is a substitute communication protocol to Transmission Control Protocol implemented primarily for creating loss-tolerating and low-latency linking between different applications.

4.     Post office Protocol (POP): POP3 is designed for receiving incoming E-mails.

5.     Simple mail transport Protocol (SMTP): SMTP is designed to send and distribute outgoing E-Mail.

6.     File Transfer Protocol (FTP): FTP allows users to transfer files from one machine to another. Types of files may include program files, multimedia files, text files, and documents, etc.

7.     Hyper Text Transfer Protocol (HTTP): HTTP is designed for transferring a hypertext among two or more systems. HTML tags are used for creating links. These links may be in any form like text or images. HTTP is designed on Client-server principles which allow a client system for establishing a connection with the server machine for making a request. The server acknowledges the request initiated by the client and responds accordingly.

8.     Hyper Text Transfer Protocol Secure (HTTPS): HTTPS is abbreviated as Hyper Text Transfer Protocol Secure is a standard protocol to secure the communication among two computers one using the browser and other fetching data from web server. HTTP is used for transferring data between the client browser (request) and the web server (response) in the hypertext format, same in case of HTTPS except that the transferring of data is done in an encrypted format. So it can be said that https thwart hackers from interpretation or modification of data throughout the transfer of packets.

9.     Telnet: Telnet is a set of rules designed for connecting one system with another. The connecting process here is termed as remote login. The system which requests for connection is the local computer, and the system which accepts the connection is the remote computer.

10. Gopher: Gopher is a collection of rules implemented for searching, retrieving as well as displaying documents from isolated sites. Gopher also works on the client/server principle.

11. WAIS (Wide Area Information Servers) is an Internet system in which specialized subject databases are created at multiple server locations, kept track of by a directory of servers at one location, and made accessible for searching by users with WAIS client programs. WAIS (pronounced "ways") uses its own Internet protocol , an extension of the Z39.50 standard (Information Retrieval Service Definition and Protocol Specification for Library Applications) of the National Information Standards Organization