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Sept 2001Chapter 2: Introduction to the web and internet 1 Introduction to the Web and Internet Questions Answered in this Chapter: What is the internet ? What are the characteristics of the internet that make it work? What are the content types on the web? How are websites created? What is behind the growth of the web and Internet?

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Sept 2001Chapter 2: Introduction to the web and internet 3 The Original WWW Like the internet, radio began as a communication medium Early market medium known as wireless telegraphy or telephony; radios point-to-point wireless messaging Demand for radio broadcasting surged in 1922 when it shifted from a point-to-point communication tool to a broadcast medium During the 1920s, all 48 states in the US had at least one radio station By 1925, 27 of the original 48 stations were out of business Revenue sources such as programming subsides from radio-set sales, radio taxes, generalized goodwill for corporate sponsors and advertising emerged as new revenue generation models The pay for service revenue model allowed radio to compete with telegraph and cut the price of telegraph by 30%

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Sept 2001Chapter 2: Introduction to the web and internet 5 Early networks Internets beginnings can be traced back to memos written in 1962 by MITs Joseph Carl Robnett Licklider outlining the galactic networking concept Great advances were made in network technology in 1960s To connect computers and permit transfer of information locally, many organizations installed Local Area Networks LAN technology was limited by geographical distance To allow computer and networks separated by larger geographical distance to communicate ARPA (Advanced Research Projects Agency) developed a Wide Area Network (WAN) called the ARPANET

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Sept 2001Chapter 2: Introduction to the web and internet 7 Networking Software The two most well-known pieces of internetworking software are the TCP and IP IP software set rules of data transfer over the network TCP software ensures the safe and reliable transfer of data With open system nature of TCP/IP development, software development and computer companies could more easily build TCP/IP compliant software and hardware TCP/IP standard network protocol laid the groundwork that enabled the deep internetworking that made internet possible

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Sept 2001Chapter 2: Introduction to the web and internet 8 What is the Internet? The internet is a collection of wires, protocols and hardware that allows the electronic transmission of data over TCP/IP Any data can be transferred over the net, e.g., email, faxes,video,voice & web pages Technically www (web) and the net are not the same.The web is an application for the net

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Sept 2001Chapter 2: Introduction to the web and internet 9 How the internet works Characteristics that allow shared access of data in a network : 1.Unique identification of each computer on the network Internet is a network of millions of computers and thousands of networks intertwined together. Thus it was important that each computer can be uniquely identified by assigning a specific Internet Protocol(IP) address. e.g.,198.108.95.145 2.Human-friendly addressing Domain Name System(DNS) gave each computer on the network an address comprising an easily recognizable letters and words instead of an IP address. e.g., www.philanthropy.com

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Sept 2001Chapter 2: Introduction to the web and internet 10 How the internet works(contd) 3.Packet Switching To remedy delays associated with unequally sized data transfers, instead of transferring files in their entirety, whole files are broken up into data packets before being transferred over the network. 4.Routing Routers are dedicated, special-purpose computers which serve as an intermediary between networks. They route packets efficiently through networks. Routers are building blocks of the internet.

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Sept 2001Chapter 2: Introduction to the web and internet 14 How the internet works (contd) 5.Reliability and Transmission control Protocol IP software handles packet deliveries and TCP handles safe delivery of packages. 6.Standardization Without the TCP/IP standardization, there would have been many negative tradeoffs, such as inflexibility and increased functional and switching costs.

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Sept 2001Chapter 2: Introduction to the web and internet 15 TCP Standardization Networking technologies are not inherently compatible. Before the development of internetworking technology an organization with networks had two options: One Alternative- allow groups to have network technology best suited to them, which was not flexible Other alternative have a standard

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Sept 2001Chapter 2: Introduction to the web and internet 16 Functions of TCP/IP Prevents loss of data Checks packets Eliminates duplicate packets Sends confirmation when the packet is received If confirmation is not received, then the packet is retransmitted Enables reliable and error-free communication over the net

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Sept 2001Chapter 2: Introduction to the web and internet 17 What Web pages are made of The entire Web is built upon three concepts: web pages (documents seen on the browser), links (connecting one web page to another), and servers (storing and transmitting the information to the browsers for display) No special software is required to create a web page Majority of pages are created using Hyper Text MarkUp Language(HTML)

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Sept 2001Chapter 2: Introduction to the web and internet 19 Contents of the web Links Internal Anchor Links: Internal anchors are used to connect with other locations within the same document. Page Links: Page links allow users to link to other web pages. Mail-to Links: Mail links are used to let users send feedback and questions directly to them. Forms Forms are basically web pages where the user can enter information on the fields provided on the page.Forms are useful in getting highly structured feedback.

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Sept 2001Chapter 2: Introduction to the web and internet 20 Contents of the web(contd) Images The most supported image formats on the Web are Graphic Image Format (GIF) and Joint Picture Encoding Group(JPEG). Multimedia Web supports multimedia file type such as images, audio and video. Capturing contents and compressing data Printed images can be captured with low cost scanners and photos can be downloaded with digital video cameras. Audio Sounds can be captured, compressed and stored for use on the web. Video Video capture cards allow users to capture the analog video output of camcorders, VCRs and DVD players.

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Sept 2001Chapter 2: Introduction to the web and internet 21 How are Web Sites Created? 1.A Web page can be made by adding text-based codes called Hyper Text Markup Language (HTML) to a text file.Text editor allows to create WebPages and gives more flexibility and control over design and layout. 2.Document conversion tools enable existing documents and new documents to be created and posted with minimal investment in learning markup language. 3.Several web authoring tools are available; e.g., Microsoft FrontPage lets users add multimedia objects such as sound and animation to their web pages. 4.High-end Web authoring tools such as Dreamweaver and Adobe GoLive offer more powerful site creation and management features, and allow expanded features such as database integration to be built in a web site.

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Sept 2001Chapter 2: Introduction to the web and internet 23 Behind the Scenes Browsers make the retrieval process transparent Uniform Resource Locator tells the browser several things about how to access the desired content: 1.The transmission protocol to access the content. e.g., Hyper Text Transfer Protocol for Web Pages, File Transfer Protocol (FTP) for transmission of files and the extended S-HTTP for a higher degree of security. 2.The name of the computer where the content can be found 3.The directory on the computer where content is stored and the name of the file containing the content.

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Sept 2001Chapter 2: Introduction to the web and internet 26 Factors behind the growth of the net Ease of content consumption Browser versatility and convenience Speed Easy to download Platform independence Ease of content creation Standards

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