History and Evolution of the Internet

Introduction to the Internet

• The Internet is the world's largest computer network.
• It interconnects millions of businesses, government agencies, educational institutions, and individual networks.
• Access to global information and instant communications at any time and anywhere is available through the Internet.

History of the Internet

• Developed by US academic institutions.
• Funded as a research network by US defense agencies.
• In 1969, the initial network was built under the name ARPANET (Advanced Research Projects Agency Network).
• ARPANET initially linked just 4 computers together.
• In the early 1970s, there was a need to develop a standard Internet protocol.
• A standard Internet protocol was needed for connecting diverse technologies.
• The Internet Protocol (IP) is still in use.
• IP data packets are datagrams, analogous to postal letters.
• Each IP data packet functions independently of the others packets.
• A problem with the IP datagram protocol is the potential loss or the re-ordering of data in transit.
• A second standard protocol developed in the 1970s was Transmission Control Protocol (TCP).
• TCP establishes a logical connection from source to destination.
• A numbered sequence of packets may flow over that connection.
• Cerf and Kahn designed TCP/IP protocol, which divides messages into packets at the sending computer.
• The packets reassemble at the receiving computer.
• In 1984, ARPANET had more than 1,000 individual computers linked as hosts.
• NSF connected NSFnet to ARPANET in 1986.
• After the connection, the network became known as the Internet.
• NSFNet terminated its network on the Internet in 1995 to resume status as a research network.
• Internet2 was founded in 1996.
• More than 550 million hosts connect to the Internet today.

Circuit Switch

• Used for phone calls.
• Electronic signals pass through several switches for a connection to be established.
• During a call, no other network traffic can use those switches.
• A Telco provider creates a dedicated circuit and connects the caller's phone to the recipient's telephone.
• The circuit remains for as long as the line is open, and packets flow between both telephones follow the same path.
• An example of a circuit-switched network.

Packet Switch

• Packet-switched networks move data in separate, small blocks (packets) based on each packet's destination address.
• Packets are reassembled in the proper sequence to make up the message when received.
• An example of packet-switching is switching on a PC and connecting to a site to download applications.
• Each packet finds its way using source and destination IP address information.
• If network congestion occurs, routers will automatically select different paths to transfer data as required.

The Internet: Benefits & ISP

• Benefits of the Internet: Communicating, Accessing & Sharing Information, Shopping, Banking & Investment, and Entertainment and leisure.
• Internet service provider (ISP) is an organization.
• ISP is an organization such as a cable company or a telephone company, that supplies connections to the Internet for a monthly fee.

Computer Networks

• It is a collection of computers and devices connected together.
• Connections are made via communications devices and transmission media, allowing computers to share resources.

Classification of Networks

• Local Area Network (LAN) covers a limited geographical area, such as a home, lab, or office.
• Metropolitan Area Network (MAN) connects LANs in a metropolitan area, such as a city or town.
• Wide Area Network (WAN) covers a large geographical area, such as a city, country, or the world.
• The Internet is the largest WAN.

Architecture of Networks

• Client-server architecture uses a server which is any computer that accepts requests from other connected computers.
• The server shares resources (files, printers, programs) with those computers.
• Clients are the other computers or devices on the network that rely on the server for its resources.
• Peer-to-peer architecture gives Each computer (peer) equal responsibilities and capabilities.
• Peers share hardware (such as a printer), data, or information with other computers on the network.
• Each computer stores files on its own storage devices.
• Each computer on the network contains both the server operating system and application software.

Network Communication Devices

• Dial-up Modems convert digital signals to analog signals so data can travel along an analog telephone line.
• A cable modem (aka a broadband modem) is a digital modem that sends and receives digital data over cable television.
• An ISDN modem sends digital data and information from and to a computer on an ISDN line.
• A DSL modem sends digital data and information from and to a computer on a DSL line.
• Other network communication devices: Wireless Modems, Network cards, Wireless Access Points, and Routers.

Network Transmission Media

• Physical, Wired Media uses Twisted-Pair Cable (e.g. LAN cable), Coaxial Cable (e.g. Cable television (CATV) network wiring) and Fiber-Optic Cable.
• Wireless media are Infrared; Broadcast Radio (e.g. Bluetooth, UWB, Wi-Fi, and WiMAX); Cellular Radio (e.g. wireless modems and cell phones).
• Microwave transmission (aka fixed wireless) sends signals from one microwave station to another using line-of-sight transmission.
• Microwave transmission is commonly used in wide-open areas such as deserts or lakes, or between buildings, or to communicate with a satellite.
• Communication Satellites receives microwave signals from an earth-based station and amplifies/strengthens them.
• The satellite broadcasts the signals back over a wide area to any number of earth-based stations.

How to Identify Devices in the Internet

• Internet Protocol address (IP address).
• Domain names like Host machines.domain names (ucsi.edu.my).
• In the mid 80s, a collection of different protocols with its own user interface proliferate.
• Examples of those protocols ate telnet, FTP, Usenet, mailto.
• Users had to learn how to use each protocol.
• The solution was the creation of WWW.
• An IP address is a number that uniquely identifies each computer or device connected to the Internet.
• A domain name is the text version of an IP address
• A top-level domain (TLD) falls under domain name.
• A DNS server translates the domain name into its associated IP address.

Other Internet Services & Domain Name

• FTP (File Transfer Protocol) is an Internet standard.
• FTP permits file uploading and downloading with other computers on the Internet.
• Many operating systems include FTP capabilities.
• An FTP server is a computer that allows users to upload and/or download files using FTP.
• The domain name can be seen with different parts.
• http://www.nps.gov/grsm/planyourvisit/wildlifeview.html (Protocol, Domain Name, Path, Webpage Name)

The World Wide Web

• It is one of the most popular services on the Internet, often called the Web.
• Contains billions of worldwide collection of electronic documents called web pages.
• A web page can contain text, graphics, audio, and video, and built-in connections, or links, to other web documents.
• A website is a related collection of web pages (e.g.: UCSI website).
• The most common protocol is the hypertext transfer protocol, HTTP.
• HTTP provides a standard form of communication between web browsers and web servers.
• A Web server is a computer that delivers requested Web pages.
• Hypertext is text displayed on a computer with references to other text that a user can click to immediately access.
• Hypermedia is a nonlinear medium of information.
• Hypermedia includes graphics, audio, video, plain text and hyperlinks.

Web 2.0 & 3.0

• Web 2.0 describes World Wide Web sites that use technology beyond the static pages of earlier Web sites.
• A Web 2.0 site offers ways for users to interact and collaborate with each other in a social media dialogue.
• Users of Web 2.0 sites are creators of user-generated content in a virtual community.
• Web 2.0 sites allow users to do more than just retrieve information.
• A user is invited to 'write' as well, or contribute to the content available to everyone in a user friendly way.
• Examples of Web 2.0 sites or technologies: Cloud computing, social networking sites, blogs, wikis, folksonomies, video sharing sites, hosted services, Web applications, and mashups.
• Semantic Web and personalization are the most important features of Web 3.0.
• The Semantic Web is a collaborative movement led by the World Wide Web Consortium (W3).
• The Semantic Web is an integrator across different content, information applications and systems.
• Common data formats are promoted on the World Wide Web.
• Technologies providing a formal description of concepts, terms, and relationships are enabled.
• Collection, structuring and recovery of linked data are enabled by these technologies.

Web Browsers, Servers, and Home Pages

• Programs running on client machines are web browsers.
• Browsers request documents using URL.
• To display a home page, the web browser software icon on the taskbar is clicked, or name is typed in the search box, to start the menu.
• Behind the scenes, the Web browser looks up its home page setting.
• The Web browser then communicates with a server maintained by the Internet access provider.
• The server translates the domain name of the home page to an IP address.
• The server sends the IP address to the computer.
• The Web browser uses that IP address to contact the Web server associated with the home page, and requests the home page.
• The Web server sends the home page to the Web browser, which formats the page for display on the screen.
• There are thirteen types of Web sites: Portal, News, Informational, Business/Marketing, Blog, Wiki, Online Social Network, Educational, Entertainment, Advocacy, Web Application, Content Aggregator and Personal.
• A computer provides web pages to a requesting browser which is a web server.
• It delivers the content using the HTTP, over the WWW.
• (Image showing browser (client app), HTTP request and web page, ActiveX controls, Java applets and any requested file on the web server)

URLs

• A unique address for a web page.
• Used to identify web pages on the internet.
• The URL format is scheme:object-address.
• The format involves a communication protocol and fully qualified domain name/path to document.
• URL includes how://where/what and :///
• (Infrastructure diagram from Client w/ browser to ISP/Name server, to web server)
• An example of a URL is http://ucsi.edu.my/students/listing.asp.

HTTP

• TCP/IP establishes the connection to the web server.
• HyperText Transfer Protocol enables the web server and client software to communicate with each other.
• HTTP communication consists of 2 phases, the request and the response.
• Each HTTP communication consists of 2 parts: a header and a body.
• The general form of an HTTP Request is as follows: HTTP method, Domain part of the URL, HTTP ver., Header fields, Blank line, and Message body.
• The most commonly used HTTP methods are GET, POST, HEAD, PUT, and DELETE.
• GET (Fetch a document), POST (Execute the document using the data in the body), HEAD (Fetch just the header of the document), PUT (Store a new document on the server), DELETE (Remove a document from the server).
• (HTTP Request Phase Diagram)
• Server Response is in the form of: Status line (i.e. HTTP/1.1 200 OK), response header fields, Blank line, Response body.
• A status code is a 3 digit number specifying the general status.
• Status code first digit indicates category of Informational, Success, Redirection, Client Error and Server Error with the digits of 1, 2 ,3, 4 and 5 respectively.
• (HTTP Response Phase Diagram)

This lesson covers the origins of the Internet, starting with ARPANET and its funding. It explains the roles of IP, NSFNet, and Internet2. It also highlights the shift from Web 1.0 to Web 2.0 and its impact.