introduction to interactivity for the web ian graham tel: 978.4548 email: ian.graham@utoronto.ca...
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Introduction to Interactivity for the Web
Ian GrahamTel: 978.4548
Email: ian.graham@utoronto.ca
Web: www.utoronto.ca/ian/talks/
What is Interactivity?
Two facets: Interactivity between person and
machine Interactivity between people
This talk focuses on the first of these facets
Presentation Overview
Description of types of interactivity
Some examples to illustrate types
Questions are encouraged always, at any time, about anything
Lunchtime seminar means…. Have lunch!
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
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
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
Browsing and Web Pages
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asdfasd asd tasdf asfd as asdf
Web Server
Internet
WebBrowser
Sd fdsa as dfsaasdf asd asd asd
asdfasd asd tasdf asfd as asdf Sd f
HTML/Web pages
E.g: http://www.utoronto.ca
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
Web Browsing advantages
It works for everyoneCan be local, or remoteCan distribute any type of data file
(HTML, Word documents, PowerPoint, etc.) Requires that the person visiting can
read these data typesBut not terribly interactive.....
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
Server Software
Internet
WebServer
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asdfasd asd tasdf asfd as asdf Sd f
WebBrowser
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dsa as dfsaasdf asd asd asd
asdfasd asd tasdf asfd as asdf
GatewayProgram
database
???
Server Software
Often called CGI programs, or Gateway programs.
Gateway between the Web server and “something else”
Example Server Programs
http://www.altavista.com ("Beaujolais Nouveau")
http://xxx.lanl.gov/find/cond-mat ( Database search tool )
Server Interaction
Interact with complex programs
Dynamically generated HTML pages
Hides resources from user harder to cheat!
Not local -- needs Web server
Browser Interaction
Several approaches Scripts in pages -- JavaScript Plugin modules Embedded Java programs
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
Scripting Examples
http://library.utoronto.ca
http://www.microsoft.com
Advanced Scripting Information
http://developer.netscape.com/tech/javascript/index.html?content=/docs/examples/javascript.html
http://msdn.microsoft.com/workshop/author/?RLD=70
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)
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
Browser Plugins
Special program to interpret data Embedded/installed on user’s computer Special formats otherwise not viewable Allows dynamic interaction with those data
Examples: http://www.utoronto.ca/ian/books/html4ed/chap2/
embed.html http://www.musicface.com
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
Java Programs
A bit like plugins, but actually mobile programs
Download the program, run it locally
Java language makes this safe
Some Java Examples
Instructional Tools http://www.dgp.utoronto.ca/people/JamesStewart/applets/
Pure Toyshttp://www.litecom.se/java/rollerboy/
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
Mixed-Mode Interactivity
JavaScript can interact with Java applets
Java programs can interact with a remote server
Java/JavaScript can interact with plugins
Multiple Interaction Levels
WebServer
Browser
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GatewayProgram
database
???
JavaScript
JavaApplet
text
form
Other program
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
Summary (2)
Client interactivity can interact with server Increased range of interaction
possibilities
More difficult to do, fewer canned tools
Introduction to Interactivity for the Web
Ian GrahamTel: 978.4548
Email: ian.graham@utoronto.ca
Web: www.utoronto.ca/ian/talks/
The End
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