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World-Wide Web. Introduction to the World-Wide Web Setting up a Web server Authoring for the Web ... Gateways and forms Access control and security. History. CERN, Geneva, 1989 Def HTTP client/server protocol Sample server Prog. lib. wwwlib 1992: callable interface in public domain

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World wide web
World-Wide Web

  • Introduction to the World-Wide Web

  • Setting up a Web server

  • Authoring for the Web ...

  • Gateways and forms

  • Access control and security


History
History ...

  • CERN, Geneva, 1989

  • Def HTTP client/server protocol

  • Sample server

  • Prog. lib. wwwlib

    • 1992: callable interface in public domain

    • ==> Development

      • Web browsers

      • New features

  • Now browsers & servers for all major architectures


Original goals
Original goals

  • Link distinct documents

    • Success

  • Facilitate collaborative authoring

    • Not so much, yet


Introduction to the world wide web
Introduction to the World-Wide Web

  • Components of Web architecture ...

  • What's the Web good for? ...

  • Basic Web Concepts ...

  • WWW Servers and Browsers ...

  • Searching on the Web …


Components of web architecture

Databases

Contents

Software

applications

Components of Web architecture …

  • HTML: Hyper Text Markup Language

  • HTTP: Hyper Text Transfer Protocol

  • CGI: Common Gateway Interface

Web

clients

Web

servers

TCP/IP-based

network

CGI


Powerful linking abilities
Powerful linking abilities ...

  • Highlight words/pictures

    • ==> Link/point to other

      • Documents

      • Sound files

      • Movie clips

    • From any point to any point


Most graphical internet service
Most graphical Internet service ...

  • Need browser w/GUI

  • Click on link to follow


What s the web good for
What's the Web good for? ...

  • Museums

  • Newspapers, magazines

  • Business

  • Investment information

  • Libraries, universities

  • Governments

  • Individuals


Basic web concepts
Basic Web Concepts ...

  • Hyperlinking ...

  • The HTML Tagging Language ...

  • The URL Concept ...

  • What's a WWW Browser? ...

  • What's a WWW Server? ...

  • HTTP ...


Hyperlinking
Hyperlinking ...

  • Home page: central doc. in Web server

    • Hyperlinks (underlined)

  • Navigate: follow hyperlinks (surfing)

    • Anywhere on Web servers in the world! ...



The html tagging language
The HTML Tagging Language ...

  • Hypertext Markup Language

  • HTML Documents

  • Describe structure of doc & hyperlinking info

    • No exact formatting

  • Example ...



The url concept
The URL Concept ...

  • Each hyperlink, 2 components:

    • Anchor text/graphics

      • Trigger hyperlink when clicked

    • Universal Resource Locator (URL) ...


Universal resource locator url
Universal Resource Locator (URL) ...

  • What to do when HL activated

  • Protocol to reach

    • Target server

    • Host system (server name) where doc is

    • Directory path

    • Filename

  • E.g., master list of all public WWW server in world

    • http://info.cern.ch/hypertext/DataSources/WWW/Geographical.html (absolute)


What s a www browser
What's a WWW Browser? ...

  • Client/server environment

  • Browser

    • Use URL

    • Retrieve Web document from Web server

    • Interpret HTML

    • Present document to user

      • Bitmap graphics ==> more than char. based

        • E.g., hyperlink: color/underline vs. reverse video

  • Example ...


Example1
Example ...

  • Protocol depends on server

    • Some browsers can access WAIS servers

    • Can start up telnet sessions

  • Can save, email, print, search, see HTML source


What s a www server
What's a WWW Server? ...

  • SW used with WWW

  • Client asks for page; server grabs & returns

  • Special scripts

    • Gateways to other info resources

    • E.g., input from forms

      • Custom scripts to process


HTTP ...

  • HyperText Transfer Protocol

  • Request browser --> server ==> new connection

    • Open connection

    • Transfer document

    • Close connection

  • Data types between server and browser

    • Text (text/html, text/plain, ...)

    • Image (image/gif, image/tiff, ...)

      • E.g., start xv to display (Preferences: Helper App's)


Www servers and browsers
WWW Servers and Browsers ...

  • Browsers ...

  • Servers ...


Browsers
Browsers ...

  • Netscape Navigator/Communicator

  • Internet Explorer

  • Mosaic (historic importance)

  • Lynx (dumb terminal)

  • Amaya (free)

    • Browser/editor (http://www.w3.org/Amaya)

  • Opera (not free)


Mosaic
Mosaic ...

  • The first publicly available browser

  • Made it happen!


Netscape navigator
Netscape Navigator ...

  • Netscape Communications Corp. (former Mosaic Comm.)


Lynx ...

  • Full-screen, character-based

    • VT100 terms, emulators

  • Arrow keys to navigate among HTML links (reverse video)

  • Bookmarks

  • Forms

  • Interactive mode: post articles to newsgroups

  • Non-interactive mode: filter HTML to formatted ASCII

  • ftp://ftp2.cc.ukans.edu/pub/lynx/


Many others
Many others

  • Came and went

  • Maybe 10% of today’s users


Servers
Servers ...

  • NCSA

  • CERN

  • Apache (48% of all servers)

  • Netscape Enterprise

  • O’Reilly’s WebStar

  • Other


NCSA ...

  • Public domain, written in C, small, fast

  • No licensing restrictions

  • Compatible with most HTTP browsers

  • Directory aliasing: doc's can be served from any physical directory structure

  • Searches, HTML forms, clickable image maps, control user access.

  • http://hoohoo.ncsa.uiuc.edu/docs/setup/PreCompiled.html


CERN ...

  • Public domain, written in C

  • No licensing restrictions

  • Compatible with most HTTP browsers

  • Directory aliasing: doc's can be served from any physical directory structure

  • Searches, clickable image maps, control user access

  • Proxy & caching

    • On firewall machines access to outside world from inside


Work in progress
Work in progress ...

  • See http://www.w3.org

  • User Interface

  • Technology & Society

  • Architecture

  • Web Accessibility Initiative

  • Other


User interface
User Interface

  • HTML Enhancements

    • http://www.w3.org/MarkUp.html

  • Style Sheets

  • Document Object Model

  • Mathematics

  • Graphics

  • Internationalization

  • Fonts

  • Amaya


Technology society
Technology & Society

  • Digital Signature Initiative

  • Metadata

  • PICS

  • Privacy

  • Security

  • Electronic Commerce


Architecture
Architecture

  • HTTP

  • Synchronized Multimedia

  • XML

  • Jigsaw

  • Libwww


Web accessibility initiative
Web Accessibility Initiative

  • Accessibility of the Web

  • Through five primary areas of work:

    • Technology

    • Guidelines

    • Tools

    • Education & outreach

    • Research & development


Secure transactions
Secure Transactions ...

  • Credit card numbers

  • Signatures (electronic)

  • Legally binding time stamps

  • Secure HTTP development

    • Authority of transactions

    • Confidentiality of info exchanged

    • http://www.commerce.net/information/standards/drafts/shttp.txt

    • email: [email protected]


Uniform naming
Uniform Naming ...

  • URL: no uniquely identify doc

    • Only instance of doc

    • No account for mirrored doc's, versions out of date

  • URN: Universal Resource Name

    • Unique doc identifier

      • Like ISBN for books

      • Return URL of closest copy?

  • URC: Universal Resource Citation (just a diff name)


Commercialization
Commercialization ...

  • Bundle browser w/systems

  • License browsers + sell

  • ==> Web onto more desktops

  • Info providers + publishers

  • Secure web ==> electronic commerce


Searching on the web
Searching on the Web ...

  • Catalogs, directories

    • Manual

    • E.g., Yahoo

  • Indices, search engines

    • Automatic

    • E.g., AltaVista


Search engines
Search Engines ...

  • "Robots," "worms," "spiders," "crawlers,” meta searchers

  • No ultimate search tool on the Web

  • Different search strategies

    • ==> Different results

  • Partial list ...

  • More info ...


Partial list
Partial list ...

  • Metacrawler ...

  • Alta Vista ...

  • WebCrawler ...

  • Lycos

  • InfoSeek

  • Copernic


Comparison
Comparison ...

  • IEEE Internet Computing, July/August 1998, pp. 78-83, http://computer.org/internet/v2n4/w4arach.htm

  • http://www.cnet.com/Contents/Reviews/Compare/Search/ (old)


More info
More info ...

  • "New Spiders Roam the Web"

    • http://www.rpi.edu/~decemj/cmc/mag/1994/sep/spiders.html

  • "WWW Robots, Wanderers, and Spiders"

    • http://web.nexor.co.uk/mak/doc/robots/robots.html

  • Netscape Web page

    • http://home.mcom.com/home/internet-search.html

    • Click Net Search button in Netscape


Internet research tool kit
Internet Research Tool Kit

  • Links to most search & research tools

  • http://www.cs.uml.edu/~haim/NetResearch_links.html


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