2440: 141 Web Site Administration

1. 2440: 141Web Site Administration Introduction to the Internet & the Web Instructor: Enoch E. Damson

2. Computer Network • Two or more computers connected together to share resources like printers and programs • Fall into two categories: • Local Area Network (LAN) – computers connected within a small geographic area like a building • Wide Area Network (WAN) – a connection of computers over a few miles or thousands of miles • E.g. the Internet Introduction to the Internet & the Web

3. Intranet • A private computer network • Uses the same concepts and technologies on the Internet to share part of an organization’s information or operation with its employees Introduction to the Internet & the Web

4. The Internet • A large collection of computers all over the world that are connected to one another • A large network of networks • Also called the “Net” Introduction to the Internet & the Web

5. Origins of the Internet No one person invented the Internet However, certain people contributed major breakthroughs Leonard Kleinrock (Massachusetts Institute of Technology): published a paper in 1961 on packet switching which was essential to the Internet Packet switching: packets of data can be sent from one place to another based on address information carried in the data J.C.R. Licklider: the first to describe an internet-like worldwide network of computers, in 1962 as the “Galactic Network" Larry G. Roberts: created the first functioning long-distance computer networks in 1965 He designed the Advanced Research Projects Agency Network (ARPANET), under the auspices of the Defense Advanced Research Projects Agency, as a means to share information on defense research Introduction to the Internet & the Web 5

6. Origins of the Internet Vinton (Vint) Cerf and Robert (Bob) Kahn: invented the Transmission Control Protocol (TCP) and the Internet Protocol (IP) in 1972 and 1973 Most credited for being the “Fathers of the Internet” TCP/IP - moves data on the modern Internet Tim Berners-Lee: invented the World Wide Web (the Web) with Robert Cailliau in 1990 while working at CERN He wrote the first web browser and invented both the HyperText Markup Language (HTML) and the HyperText Transmission Protocol (HTTP) HTML – used for format contents on the Web HTTP - used to request and transmit web pages between web servers and web browsers Al Gore: when in congress, was instrumental in overseeing the US legal framework and other government issues related to the internet Introduction to the Internet & the Web 6

7. Origins of the Internet… • The US Department of Defense (DoD) created the • Advanced Research Projects Agency (ARPA) – research led to the creation of the • Advanced Research Projects Agency Network (ARPANET) – an experimental WAN primarily for academic research, scientific, and military purposes • Made up of about four main computers located at: • UCLA • UCSB • University of Utah • SRI International Introduction to the Internet & the Web

8. Internet Resources • Resources used on the Internet include: • World Wide Web (WWW) – used to organize resources (like text documents, graphics, music, video clips) to make them easily accessible • Electronic Mail (E-mail) – used to communicate with people all over the world • Commercial Services – all kinds of business services that market and sell products and services • Newsgroups – an electronic discussion group Introduction to the Internet & the Web

9. World Wide Web (the Web) • Origins started at the European Laboratory for Particle Physics (CERN) in Geneva, Switzerland • By Tim Berners-Lee in 1990/91 • Also called the “Web” • After the initial surge of interest on the Web, a need arose for a standards organization to set recommended practices for the Web • The World Wide Web Consortium (W3C) was founded to meet the growing need on the Web Introduction to the Internet & the Web

10. World Wide Web Consortium (W3C) • The W3C (http://www.w3.org) was founded in 1994 at the Massachusetts Institute of Technology (MIT) • Led by Tim Berners-Lee • The W3C sets standards for the Web and provides an open, nonproprietary forum for industry and academic representatives to add to the evolution of the Web • Various committees that make up the W3C look to expand and set standards for many new Web technologies such as: • Extensible Hypertext Markup Language (XHTML) • Extensible Markup Language (XML) • Cascading Style Sheets (CSS) Introduction to the Internet & the Web

11. Web Terminologies • Link (hyperlink or hypertextlink) – text, graphic, or other Web elements that connects to additional data on the Web • Web Page – a document on the Web • Uniform Resource Locator (URL) - a unique address used to identify documents on the Web • Web Browser – software for displaying Web pages • E.g. Mosaic, Navigator, Internet Explorer, Opera • Web server – makes Web pages available on the Web • Hypertext Transfer Protocol (HTTP) – the default protocol (program) used on the Web to help transfer files • Hypertext Markup Language (HTML) – the language used to define the structure and content of Web pages Introduction to the Internet & the Web

12. Hypertext Markup Language (HTML) • HTML is a markup language – a structured language to identify common sections of a document such as headings, paragraphs, and lists • Tim Berners-Lee formally created HTML in 1992 at the CERN labs (in Switzerland) originally for simple document structure • Berners-Lee adopted only elements of SGML (Standard Generalized Markup Language) for representing basic office documents such as memos and reports • SGML – an international standard for representing text in an electronic form for exchanging documents independently • The first draft included elements such as titles, headings, paragraphs, and lists Introduction to the Internet & the Web

13. Properties of HTML • Web browsers interpret HTML markup elements and display the results • HTML adopts many features of SGML including: • Cross-platform compatibility • Markup elements such as headings, lists, paragraphs, etc • HTML is an open, nonproprietary language Introduction to the Internet & the Web

14. Structure of HTML • HTML uses a combination of tags, attributes, and values to generate results • E.g. <body bgcolor=“red”> • body – is the element in a tag • bgcolor – is the attribute of the <body> tag • red – is the value of the attribute in optional single/double quotes Introduction to the Internet & the Web

15. <html> <head> <title> </title> </head> <body> </body> </html> HTML Page Format Introduction to the Internet & the Web

16. Style Sheets • SGML and HTML were designed to represent document structure, not style • Style elements such as <fonts> were introduced by browser developers to help HTML authors bypass this HTML design limitation • Mixing style information within a document limits the cross-platform compatibility of Web contents • Style sheets separate display properties from the content • The separation of style and structure was accomplished in 1996 by the W3C’s specification for a Web style language named Cascading Style Sheets (CSS) Introduction to the Internet & the Web

17. Cascading Style Sheets (CSS) • Allows authors to create style rules for elements and express them externally in a style sheet document • Used mainly to separate presentation from the structure of a page • Presentation – “looks” of a page • Structure – “meaning” of a page’s content • CSS rules are easy to create yet very powerful • The current trend is to rely more heavily on style sheets to control visual display of content Introduction to the Internet & the Web

18. Extensible Hypertext Markup Language (XHTML) • Combines the strict rules and syntax guidelines of XML (eXtensible Markup Language) with HTML Introduction to the Internet & the Web

19. XHTML Page Format • XHTML pages follow a basic structure as follows Introduction to the Internet & the Web

20. XHTML Page Format… • Below are the explanations to the XHTML page structure • XML declaration – identifies document as XHTML document • Document Type Definition (DTD) – URL points to a file that outlines the available elements, attributes, and usage and the three XHTML DTDs available are: • XHTML Transitional – helps to maintain backward compatibility with older browsers and access to HTML 4.01 elements • XHTML Strict – does not provide any HTML elements for page appearance • XHTML Frameset – gives access to HTML elements for framesets • XHTML Names – URL points to a files that gives detailed information about the particular XML vocabulary (XHTML) Introduction to the Internet & the Web

21. HTML vs. XHTML • Some major differences between HTML and XHTML include the following: • All element attributes names are in lowercases • E.g. <p> instead of <P> • All attribute values must be contained within single or double quotes • E.g. <body bgcolor=“#ffffff”> instead of <body bgcolor=#ffffff> • All nonempty elements must have a closing tag • E.g. <p>XHTML</p> instead of <p>HTML • All empty tags should be written with a space and a / symbol at the end of the tag • E.g. <br /> instead of <br> Introduction to the Internet & the Web

22. XML • XML (eXtensible Markup Language) • A set of guidelines for delimiting text through a system of tags • Follows rigid guidelines Introduction to the Internet & the Web

23. Dynamic HTML (DHTML) • A collection of different technologies including: • XHTML • JavaScript • DOM (Document Object Model) • CSS Introduction to the Internet & the Web

24. JavaScript • Developed by Netscape in 1996 • Has become almost as popular as HTML • Has nothing to do with the Java Programming Language • But Netscape licensed the name from Sun Microsystems in hopes of increasing acceptance of the new scripting protocol Introduction to the Internet & the Web

25. Web Application • Web site that delivers dynamic data • Involves tools like: • Database – stores data for future retrieval and update • Server-side scripting – such as like Active Server Pages (ASP), Java Server Pages (JSP), ASP.NET, ColdFusion, PHP, etc Introduction to the Internet & the Web