ch01-Internet & Web Basics &.ppt

ch01-Internet & Web Basics &.ppt

• 1.
  Basics of Web Design Chapter1 Internet & Web Basics Key Concepts 1
• 2.
  Learning Outcomes  Describethe evolution of the Internet and the Web  Explain the need for web standards  Describe universal design  Identify benefits of accessible web design  Describe the purpose of web browsers and web servers  Identify Internet protocols  Define URIs and domain names  Describe XHTML and HTML  Create your first web page  Use the body, head, title and meta elements  Name, save, and test a web page 2
• 3.
  The Evolution ofthe Internet • Internet – Interconnected network of computer networks – ARPAnet • Advanced Research Project Agency • 1969 – four computers connected – NSFnet • National Science Foundation – Use of the Internet was originally limited to government, research and academic use – 1991 Commercial ban lifted 3
• 4.
  Reasons for Internet Growthin the 1990s • Removal of the ban on commercial activity • Development of the World Wide Web by Tim Berners-Lee at CERN • Development of Mosaic, the first graphics-based web browser at NCSA • Convergence of technologies: ₋ Affordable personal computers with GUI Operating Systems ₋ Affordable Internet service providers 4
• 5.
  Web Standards and theW3C Consortium W3C – World Wide Web Consortium  Develops recommendations and prototype technologies related to the Web  Produces specifications, called Recommendations, in an effort to standardize web technologies  WAI – Web Accessibility Initiative 5
• 6.
  Web Accessibility “The powerof the Web is in its universality. Access by everyone regardless of disability is an essential aspect.” – Tim Berners-Lee  Accessible Websites provide accommodations that help individuals to individuals with visual, auditory, physical, and neurological disabilities overcome barriers 6
• 7.
  Network Overview Network two ormore computers connected together for the purpose of communicating and sharing resources 7
• 8.
  Internet, Packets andRouting • Internet is a network of computer networks • Data is transmitted by packet switching using the standard Internet Protocol (IP) • Packet – a unit of information carriage • Packet switching – process of moving packets from one node (computer device) to another 8
• 9.
  Internet, Packets andRouting • At the sender, data is broken into packets and sent to the nearest node (router) • At each router, it sends the packet to another router that is closer to the final destination • At the receiver, packets are reassembled to get the original data • A simple analogy: mailing system 9
• 10.
  Internet v.s. Web •The Internet a inter-connected computer networks, linked by wires, cables, wireless connections, etc. • Web a collection of interconnected documents and other resources. • The world wide web (WWW) is accessible via the Internet, as are many other services including email, file sharing, etc. 10
• 11.
  How does theInternet Work? • Through • communication protocols set of Rules that describe the methods used for clients and servers to communicate with each other over a network. – IP (Internet Protocol) – TCP (Transmission Control Protocol) – UDP (User Datagram Protocol) – DNS (Domain Name Service), – SMTP (Simple Mail Transmission Protocol) – FTP (File Transmission Protocol) 11
• 12.
  TCP/IP Protocol Suites HTTP,FTP, Telnet, DNS, SMTP, etc. TCP, UDP IP (IPv4, IPv6) 12
• 13.
  HTTP Hypertext Transfer Protocol A set of rules for exchanging files such as text, graphic images, sound, video, and other multimedia files on the Web.  Web browsers send HTTP requests for web pages and their associated files.  Web servers send HTTP responses back to the web browsers. HTTP Request HTTP Response 13
• 14.
  IP Address • Eachdevice connected to the Internet has a unique numeric IP address. • These addresses consist of a set of four groups of numbers, called octets. 74.125.73.106 will get you Google! • An IP address may correspond to a domain name. 14
• 15.
  • The WorldWide Web (commonly shortened to the Web) is a system of interlinked, hypertext documents accessed via the Internet. • It is created to share files/documents and overcome the barrier of different file formats • Hypertext refers to text on a computer that will lead the user to other, related information on demand. The World Wide Web (WWW) 15
• 16.
  Basics of theWWW • Hypertext: a format of information which allows one to move from one part of a document to another or from one document to another through hyperlinks • Uniform Resource Locator (URL): unique identifiers used to locate a particular resource on the network • Markup language: • defines the structure and content of hypertext documents. Ex: HTML • A browser is a software program which interprets the HTML documents and displays it on the user’s screen. 16
• 17.
  Putting it AllTogether 17
• 18.
  Client-Server Model • WWWuse classical client / server architecture • Client :web browsers, used to surf the Web • Server :web server , used to supply information to browsers Page request Client running a Web Browser Server running Web Server Software (IIS, Apache, etc.) Server response HTTP HTT P 18
• 19.
  How do WebServers work? – Client specifies document at a specific web address that is desired (specified by a URL) • Ex: http://www.cs.pitt.edu/ – If the document is HTML or text, the server simply forwards it back to the client • If it is text, it is shown unaltered in the browser • If it is HTML it is rendered in the client's browser – HTML tags are interpreted and result is shown to the user 19
• 20.
  What is aWeb Page? • Web pages are text files containing HTML • HTML – Hyper Text Markup Language – A notation for describing • document structure (semantic markup) • formatting (presentation markup) • The markup tags provide information about the page content structure 20