COP 3813 Intro to Internet Computing Prof. Roy Levow Lecture 1

World Wide Web (WWW)  Created –By Tim Berners-Lee –In 1990 –At CERN, European Org. for Nuclear Research –Developed the web concept

First Browser  Moasic –Developed by team led by Marc Andreesen –In 1993 –At NCSA, National Center for Supercomputer Applications –Later Andreesen developed Netscape browser based on Mosaic

Many Browsers  Microsoft Internet Explorer  Netscape (AOL)  Mozilla  Opera  Lynx (text only)  …

World Wide Web Consortium (W3C)  Founded in 1994  By Andreesen  Sets standards for WWW –Called Recommendations

Languages for Web Page Development  Originally HyperText Markup Language = HTML –Describes content and style but not layout details  Now Extensible HTML = XHTML

Programming within Web Pages  Add dynamic elements to web pages  Interpreted Script Langauges –JavaScript –VBScript  Compiled code –Java  Microsoft.NET Framework  Dynamic HTML

Compatability Issues  Variety of Technologies  New Extensions  Not all web pages work with all browsers  Developers –Choose a platform –Create different versions for different platforms

Browsers  Obtain web pages and other content over the web  Render HTML and extensions  Support navigation over links  Many additional display and usability

Uniform Resource Locator (URL)  Standard “address” for web content  Format –Service type –Separator –Host domain name:port –Directory and file path –parameters

Browser Plug-ins  Extend functionality of browser  Many are available  User notified when plug-in is needed  Downloaded and stored in designated directory  Automatically run when required

Browser History, etc.  History –Retains record of recently visited sites  Cache –Contains copies of recently loaded web content  Cookies –Small files that are stored by a site and can later be fetched by the same site for tracking

Other Web Services  File transfer –ftp or http   Instant Messaging