Introduction to Interactivity for the Web

1
Introduction to Interactivity for the Web

• Ian Graham
• Tel [phone]
• Email ian.graham_at_utoronto.ca

2
What is Interactivity?

• Two facets
• Interactivity between person and machine
• Interactivity between people
• This talk focuses on the first of these facets

3
Presentation Overview

• Description of types of interactivity
• Some examples to illustrate types
• Questions are encouraged always, at any time,
  about anything

4
Interactivity and the Web

• Two ways to interact with the Web
• Locally -- Interact with your browser
• Globally/Remotely -- Interact with something out
  there
• Both have strengths and weaknesses and overlap

5
Simplest Web Browsing

• The standard way we use the Web
• Click on a hypertext link browser goes out and
  retrieve a file from somewhere else, and displays
  it.
• Initially the only type of interactivity

6
1. Web Browsing

• It is a static interactivity
• Sequences are fixed when pages are written
• Viewer may choose different paths, but the pages
  are always the same

7
Browsing and Web Pages
Web Server
Web Browser
HTML/Web pages
Sd fdsa as dfsa asdf asd asd asd asdfasd asd
t asdf asfd as asdf Sd f
Internet
E.g http//www.utoronto.ca
8
Web Browsing

• Interactivity can be either remote, or local
• Remote -- pages are on a Web server
• Local -- pages are on a local drive, or CD-ROM
• Either is fine, if the information is static

9
Web Browsing advantages

• It works for everyone
• Can be local, or remote
• Can distribute any type of data file (HTML, Word
  documents, PowerPoint, etc.)
• Requires that the person visiting can read these
  data types
• But not terribly interactive.....

10
2. Software on the Server

• Interact with software on the Web server
• HTML forms, clickable images
• Information sent to server, for processing
• Server sends back results, based on information
  sent.
• Not static -- response depends on choices,
  different for each user

11
Server Software
Web Server
Gateway Program
database
Web Browser
???
Sd fdsa as dfsa asdf asd asd asd asdfasd asd
t asdf asfd as asdf Sd f
Internet
12
Server Software

• Often called CGI programs, or Gateway programs.
• Gateway between the Web server and something
  else

13
Example Server Programs

• http//www.altavista.com ("Beaujolais Nouveau")
• http//snow.utoronto.ca/Learn2/tsscale.htm (
  Quiz tool )

14
Server Interaction

• Interact with complex programs
• Dynamically generated HTML pages
• Hides resources from user
• harder to cheat!
• Not local -- needs Web server

15
Browser Interaction

• Several approaches
• Scripts in pages -- JavaScript
• Plugin modules
• Embedded Java programs

16
Scripting Interaction

• Small script programs, part of the HTML
  document, that respond to what the user types in.
• Basic interactions supported
• interact with images, hypertext links, forms

17
Scripting Examples

• http//library.utoronto.ca
• http//courseware.utoronto.ca1800/SCRIPT/jaym/scr
  ipts/student/serve_questions?_homepage_homepage
  (login required)
• Advanced Scriptinghttp//developer.netscape.com/
  tech/javascript/index.html?content/docs/examples/
  javascript.html

18
Scripting Advantages

• Local interaction
• Does not need Internet
• Does not depend on network speed
• Disadvantages
• Local interaction
• Transparent to reader (can cheat, if know how)

19
Current Scripting Issues

• Netscape / Microsoft Incompatibility
• Use two different ways of programming complex
  scripts
• universal scripts hard, if not impossible
• New standards will help a lot

20
Browser Plugins

• Special program to interpret data
• Embedded/installed on users computer
• Special formats otherwise not viewable
• Allows dynamic interaction with those data
• Examples
• http//www.utoronto.ca/ian/books/html4ed/chap2/emb
  ed.html

21
Plugin Advantages

• Can process/interact with different data
• Streaming Audio/video
• Multimedia presentations
• Spreadsheet data, Virtual Reality
• Problems
• Must install the plugin on all machines

22
Java Programs

• A bit like plugins, but actually mobile programs
• Download the program, run it locally
• Java language makes this safe

23
Some Java Examples

• Instructional Tools http//www.dgp.utoronto.ca/peo
  ple/JamesStewart/applets/
• Pure Toyshttp//www.litecom.se/java/rollerboy/

24
Applets -- Plus/Minuses

• Run locally, and can be downloaded
• Can be distributed on CD-ROMS
• Can be slow to download, or to run
• Java compatibility problems

25
Mixed-Mode Interactivity

• JavaScript can interact with Java applets
• Java programs can interact with a remote server
• Java/JavaScript can interact with plugins

26
Multiple Interaction Levels
Web Server
Browser
Gateway Program
database
JavaScript
???
text
Java Applet
form
Other program
27
Summary

• Interactivity on the Browser
• Script programs (JavaScript)
• Embedded plugins/objects
• Java applets
• Interactivity on the Server
• Server programs, interacting with browser user
  input mechanisms

28
Summary (2)

• Client interactivity can interact with server
• Increased range of interaction possibilities
• More difficult to do, fewer canned tools

29
Introduction to Interactivity for the Web
The End

• Ian Graham
• Tel [phone]
• Email ian.graham_at_utoronto.ca