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An Introduction to the Internet and the World Wide Web: Concepts and Tools

This chapter offers a comprehensive overview of the Internet and the World Wide Web, outlining their historical origins, key components, and essential tools used in web development. Learn about ARPAnet, NSFnet, TCP/IP, web browsers, and servers, along with programming languages like HTML. By the end of this lesson, students will have a foundational understanding of Internet concepts, how they connect various computer networks, and the technologies involved in web development.

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An Introduction to the Internet and the World Wide Web: Concepts and Tools

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  1. CHAPTER 1 Internet & World Wide Web

  2. Topics • A Brief Introduction to the Internet • The World Wide Web • Web Browsers • Web Servers • Uniform Resource Locator • Tools and Web Programming Languages

  3. Learning Outcomes At the end of this lesson, students should be able to: • Understand history and concepts related to Internet and World Wide Web. • Understand a number of tools and web programming languages that are used in web development.

  4. A Brief Introduction to the Internet Origins • ARPAnet - late 1960s and early 1970s. • For ARPA-funded research organizations. • BITnet, CSnet - late 1970s & early 1980s. • Was built for email and file transfer for other institutions.

  5. A Brief Introduction to the Internet • NSFnet - 1986 • Originally for non-DOD funded places. • Initially connected five supercomputer centers. • By 1990, NSFnet had replaced ARPAnet for non-military uses. • Soon became the network for all (by 1990). • NSFnet eventually became known as the Internet.

  6. A Brief Introduction to the Internet What the Internet Is • A world-wide network of computer networks. • At the lowest level, since 1982, all connections use TCP/IP. • TCP/IP hides the differences among devices connected to the Internet. • Internet is actually a network of networks rather than a network of computers.

  7. A Brief Introduction to the Internet IP Address • Every node has a unique numeric address. • Form: 32-bit binary number. • Usually written as four 8-bit numbers, separated by periods. • Example: 191.57.126.0 8 bits 8 bits 8 bits 8 bits

  8. A Brief Introduction to the Internet • New standard, IPv6, has 128 bits (1998) • Organizations are assigned groups of IPs for their computers. • Example: A small organization may be assigned 256 IP addresses, such as 191.57.126.0 to 191.57.126.255.

  9. The World Wide Web Origins • Tim Berners-Lee at CERN proposed the Web in 1989. • Purpose: to allow scientists to have access to many databases of scientific work through their own computers.

  10. The World Wide Web • Hypertext- text with embedded links to text in other documents to allow non-sequential browsing of textual material. • Hypermedia – more than just text – images, sound, etc.

  11. Web Browser • Mosaic - NCSA (Univ. of Illinois), in early 1993. • First to use a GUI, led to explosion of Web use initially for X-Windows, under UNIX, but was ported to other platforms by late 1993. • Browsers are clients - always initiate, servers react (although sometimes servers require responses).

  12. Web Browser • Most requests are for existing documents, using HyperText Transfer Protocol (HTTP). • But some requests are for program execution, with the output being returned as a document. • Example of web browsers: Netscape, Opera, Internet Explorer, Mozilla, Firefox, Google Chrome, Safari.

  13. Web Server • Provide responses to browser requests, either existing documents or dynamically built documents. • Example of web server: Apache, Microsoft Internet Information Server.

  14. Uniform Resource Locator (URL) The Structure of URLs • Taking http://www.mydomain.net/~rdralph/rdralph/ as an example.

  15. Uniform Resource Locator (URL) Common Internet Protocols • There are several protocols used commonly on the Internet to get to a variety of sites which support them. • The protocol which supports the World Wide Web - just one component of the Internet - is http - hypertext transfer protocol.

  16. Uniform Resource Locator (URL) Common Internet Protocols

  17. Uniform Resource Locator (URL) Common Internet Protocols

  18. Uniform Resource Locator (URL) Host Domain Names • Form of host domain names: • The Location name is almost always mnemonic - an abbreviation of the location name or an acronym for it. • A lot of the time the location name is not abbreviated at all.

  19. Uniform Resource Locator (URL) • The domain can tell us what type of site we can expect to be visiting. Common Domain Acronyms

  20. Uniform Resource Locator (URL) • Some sites use a geographical approach in their domains. • The last two positions in the domain of a WWW site outside the US often represents the country. • Universal two-letter country codes are used. For example: my= Malaysia, sa = Saudi Arabia, uk = The United Kingdom, sg = Singapore

  21. Uniform Resource Locator (URL) Paths in URLs • The tilde (~) generally precedes the name of a directory assigned to a person. • In the URL http://metalab.uniten.edu.my/~mia, for example, the mia part indicates an account name associated with the author mia.

  22. Tools and Web Programming Languages HTML • To describe the general form and layout of documents. • An HTML document is a mix of content and controls. • Controls are tags and their attributes.

  23. Tools and Web Programming Languages • Tags often delimit content and specify something about how the content should be arranged in the document. • Attributes provide additional information about the content of a tag.

  24. Tools and Web Programming Languages XML • A meta-markup language. • Used to create a new markup language for a particular purpose or area. • Because the tags are designed for a specific area, they can be meaningful. • No presentation details. • A simple and universal way of representing data of any textual kind.

  25. Tools and Web Programming Languages JavaScript • A client-side HTML-embedded scripting language. • Only related to Java through syntax. • Dynamically typed and not object-oriented. • Provides a way to access elements of HTML documents and dynamically change them.

  26. Tools and Web Programming Languages Java • General purpose object-oriented programming language. • Based on C++, but simpler and safer. • Focus is on applets and servlets.

  27. Tools and Web Programming Languages Perl • Provides server-side computation for HTML documents, through CGI. • Perl is good for CGI programming because: • Direct access to operating systems functions • Powerful character string pattern-matching operations • Access to database systems

  28. Tools and Web Programming Languages • Perl is highly platform independent, and has been ported to all common platforms. • Perl is not just for CGI.

  29. Tools and Web Programming Languages PHP • A server-side scripting language. • An alternative to CGI. • Similar to JavaScript. • Great for form processing and database access through the Web.

  30. Tools and Web Programming Languages Recent technology in web development: • AJAX • Java Web Software (e.g: servlets, NetBeans, JavaBeans) • ASP.NET • Ruby • Rails

  31. Tools and Web Programming Languages Tools for Creating Web Page • Adobe Dreamweaver (Latest version CS5) • Microsoft Front Page • Adobe PageMill

  32. References • Programming the World Wide Web, Sixth Edition Author: Robert W. Sebesta Publisher: Addison-Wesley • NetStrider Tutorial: Uniform Resource Locators <http://www.netstrider.com/tutorials/URL/> Last accessed: 22nd June 2009

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