WWW

1. WWW (some definitions) • The World Wide Web is an architectural framework for accessing linked documents spread over thousands of machines all over the Internet. • World Wide Web - the collection of computers connected to the Internet consisting of servers providing Web-based services and clients using these services.

2. WWW History • 1945 – Vannevar Bush Vannevar Bush writes an article, “As We May Think”,in Atlantic Monthly about a photo-electrical-mechanical device called a Memex, for memory extension, which could make and follow links between documents on microfiche.

3. WWW History • 1945 – Vannevar Bush “When data of any sort are placed in storage, they are filed alphabetically or numerically, and information is found…by tracing it down from subclass to subclass. It can be in only one place, unless duplicates are used…Having found one item, moreover, one has to emerge from the system and re-enter on a new path.”

4. WWW History • 1945 – Vannevar Bush “The human mind does not work that way. It operates by association. With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain.”

5. WWW History • 1965 – Ted Nelson • Coined the term “hypertext” • “Xanadu”: Nelson’s “docuverse” “A File Structure for the Complex, the Changing, and the Indeterminate.” 20th National Conference, New York, Association for Computing Machinery, 1965.

6. WWW History • 1965 – Doug Engelbart’s NLS • NLS (online system) • 1968: Mouse-based text editing • 1968: Multiple text windows • 1970: “NLS Journal” first online magazine

7. WWW History 1966: Engelbart’s Workstation

8. WWW History * • 1989 • The initial proposal for a web of linked documents came from CERN (European center for nuclear research) physicist Tim Berners-Leein March 1989 • "Information Management: A Proposal" written by Tim BL and circulated for comments at CERN

9. WWW History • 1990 – Tim Berners-Lee • “This proposal concerns the management of general information about accelerators and experiments at CERN. It discusses the problems of loss of information about complex evolving systems and derives a solution based on a distributed hypertext system.”

10. WWW History • 1991 • The first (text-based) prototype was operational 18 months later. • In December 1991 a public demonstration was given at the Hypertext ’91 conference in San Antonio, Texas.

11. WWW History • 1993 • Development continued during the next year, culminating the release of the first graphical interface, Mosaic, in February 1993.

12. WWW History – First Browser (Mosaic)

13. WWW History • 1994 • Mosaic was so popular that an year later, its author, Marc Andreessen left the National Center for Supercomputing Applications, where Mosaic was developed, to form Netscape Communications Corp. (whose goal was to develop clients, servers and other Web software) • In 1995 • when Netscape went public, investors paid 1.5 billion for the stock

14. WWW History • 1994 • CERN and M.I.T signed an agreement setting up the WWW consortium (further developing the web, standardizing protocols) • MIT runs the U.S. part. The European part is run by the French Research Center INRIA • The best place to get information about the web is (naturally) on the web itself, at the consortium home page www.w3.org

15. WWW History • 1995 - 2001 • “Internet Boom” • “Dot Com Era” • Businesses obtained domain names • Companies established Web sites • Use of email in business ubiquitous • Trademarked domain names

16. WWW History • 1995 – 2001 • “Dot coms” like AOL, Yahoo, Netscape, Real Networks, Google, Verisign • Highly inflated stock prices • Huge IPOs (initial public offerings) • Instant billionaires • “Internet Explorer” takeover • Time Warner/AOL merger

17. WWW Architecture • The Web is basically a client-server system • Client side: From users’ point of view, the Web consists of a vast, worldwide collection of documents, usually just called pages for short. • Each page may contain links (pointers) to other, related pages, anywhere in the world • This process may be repeated indefinitely, possibly traversing hundreds of linked pages. • Pages that point to other pages are said to use hypertext.

18. WWW Architecture • Client side: Pages are viewed with a program called a browser. (Mosaic and Netscape are two popular ones) • The browser fetches the page requested, interprets the text and formatting commands that it contains, and displays the page properly formatted on the screen. • Strings of text that are links to other pages, called hyperlinks, are highlighted, either by underlining, displaying them in special color or both.

19. WWW Architecture • Server side: Every web site has a server process listening to TCP port 80 (will discuss TCP in details in later lectures) for incoming connections from clients (normally browsers). • The protocol that defines the legal requests and replies is called HTTP. (we will review it in detail later) • The server will then either send the requested file to the client (in a response), or deny the request. Example: http://support.microsoft.com/kb/318380/en-us • In-class example of what happens to a client request to http://www.w3.org/hypertext/WWW/The Project.html

20. WWW History • Web Servers • Microsoft Internet Information Server (IIS) • Apache (Linux) • Lotus Domino/ Websphere (IBM)

21. WWW History Web Servers by Type (41 million) (source: Netcraft)

22. WWW History Web Server Marketshare (source: Netcraft)