Introduction to the Web ARPANET Beginning late 1960’s Included about a dozen ARPA sponsored Universities ARPA: Advanced Research Projects Agency (US Defense Dept.) Goal was to provide a network of interconnected computers Main intention was to provide access to remote computers to facilitate research Operating at 56 Kbaud (56k bits/second)! Conventional telephone communication at the time was 110 b/s Unexpected consequence – email (electronic mail)!

Network communication Packet Switching Divide message into discrete “packets” Send then independently Reassemble on the receiving end Allowed for simultaneous transmissions by multiple users No central control “nodes” behave independently Network can expand/contract as needed

Transmission Protocols TCP (Transmission Control Protocol) Developed for original ARPANET Ensured messages were properly routed between sender and receiver within the network IP (Internet Protocol) more networks developed IP invented to handle communication between networks Combination is known as TCP/IP Allows for a “network of networks”

Network Expansion Initial network use limited Universities and research institutions Later, it was expanded to military use Eventually, the government opened it up to commercial use Initially - resentment in academic community But, it led to substantial investment, competition, and expansion by businesses Increase in “bandwidth”

World Wide Web Two inventions provided standardization for information sharing Both in content formatting and transmission Developed by Tim Berners-Lee of CERN (European Nuclear Research Organization) HTML HyperText Markup Language Enables hyperlinked text documents HTTP HyperText Transfer Protocol Communication protocol for sending info across the web Mosaic (1993) Web-browser led to explosive growth of web use developed by University of Illinois - Marc Andressen (later developed Netscape) Today: Firefox (Netscape), Chrome, IE/Edge, Safari, …

World Wide Web Consortium (W3C) Founded by Time Berners-Lee in 1994 Developed nonproprietary, interoperable technologies for the WWW Q: What is meant by nonproprietary???? Q: What is meant by interoperable??? Primary goal – make the web universally accessible Also a standardization organization Web technologies standardized by the W3C are called Recommendations Some recommendations include HTML, XHTML, CSS and XML www.w3.org

Web Technology Web is client/server technology Client (web browser) requests resources from web servers Resource – any object retrieved from a web server, such as an XHTML document, image, video, audio, Database information, etc. Web servers Service the request Use specialized software (apache, IIS)

Web 2.0 Term coined in 2003 by Dale Dougherty of O’Reilly Media Refers to a shift in web usage towards more collaborative, community-based sites and usage Prior usage was primarily information dissemination from businesses and other providers (Web 1.0) Social networking sites, blogs, wikis, etc. Facebook, Wikipedia, YouTube, Ebay, … Involves the user – they create, organize, share, critique, update, etc. the content The future: Semantic Web Instead of just sending and reading data on the web, obtain meaning from the data (semantics)