Technology Tradeoffs

1
Technology Tradeoffs

• John H. Krantz
• Hanover College
• Workshop on Web Research
• Centre for Affective Sciences, May 2008

2
Outline

• Terms
• General Perspective
• Main Comparison
• Server-Side Solutions
• Client-Side Solutions

3
Some General Terms

• Server vs. Client
• Server is machine/software the study resides
• Client is the machine/software in use by the
  participant

4
Some General Terms

• Push vs. Pull
• Client-Pull information is drawn from server at
  request of client browser
• More polite
• Server-Push information is driven by the server
• What is presented is now no longer under the
  control of the participant

5
Some General Terms

• IP address
• Machine Address on the network
• IVp4 xxx.xxx.xxx.xxx
• IVp6 coming down the pike
• In many cases dynamically assigned
• For an server, try to get fixed IP address
• Domain Name
• We dont like numbers
• Names to make machine location more memorable
• Tiny URL

6
Some General Terms

• Protocols and URLs
• A protocol is the means of communicating
• Sort of like a language
• E.g. hypertext transfer protocol (http) vs. file
  transfer protocol (ftp) vs. hypertext transfer
  protocol secured (https)
• Uniform Resource Located
• Common format for getting formation
• Protocol//server.domain/(path/filename)
• http//psych.hanover.edu/

7
Some General Terms

• Internet Connectivity
• People connect in different ways
• Modem
• Cable modem
• Wireless
• LAN
• These difference impact time to download and,
  thus, willingness to continue

8
Some General Terms

• Technical Variance
• Data variation resulting from the use of
  technology
• Denial of Participation
• Prevention or reduced likelihood of participation
  based upon the technical requirements of study
• e.g., visually impaired

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General Perspective

• Web is a constantly changing environment
• Commercial issues are not the same as ours
• Lowest Common Denominator (Possible)
• The more complex the technology the more
  participants you lose
• Loss is not random
• Complexity also often, but not always adds delay,
  and people are impatient on the web
• Know the reach of your technology

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General Issues Continued

• Population is changing
• Early studies mostly male (Krantz Dalal, 2000)
• More Recent studies mostly female (e.g., Draper
  Elmer, 2008)
• Feminization of Psychology
• Still topic and probably technology dependent
  (e.g., Braun Drew, 2008)
• May well interact with technology

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Server-Side vs. Client-Side

• Server-Side

• Client-Side

• The experiment is run on the server
• Complexity is on the server
• The client needs only a browser with minimal
  capabilities
• Forms, Dynamically Created Web pages
• All actions require return to the server

• The experiment is run on the clients machine
• Complexity is on the client?
• Often requires plugin
• JavaScript, Flash Player, Java interpreter, etc.
• Some will not be pre-installed
• No need to worry about network traffic once
  experiment begins

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Division is extreme

• Every experiment uses both server-side and
  client-side operations
• At the minimum
• on the server-side, experiment must send page(s)
  and collect data
• One the client-side, participant must have
  browser to display html and forms

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Server-Side Solutions

• Minimal requirements on the client side
• HTML
• The basic language of web pages
• Forms
• Goes back to the early versions of Mosaic (the
  first media capable browser)

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CGI

• Common Gateway Interface
• Interface between server and other program or
  script
• Perl and PHP
• Often used to handle the data in experiments
• Can do anything any program can do

15
Dynamic Webpage Generation

• Use some CGI Mechanism to generate web pages on
  fly
• Often from some database as well as from
  information from client
• PHP
• a common open source solution can run on many
  server platforms
• ASP
• Microsofts version and requires their server
  platform
• Requires browser that can handle these pages,
  most can these days

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Server-Side Summary

• Advantages

• Disadvantages

• Low requirements for Client
• Single known platform for most program execution
• Excepting HTML and Form interpretation
• Great flexibility is possible

• Limited control of display
• Only what is possible in HTML, XML, PHP
• Timing is limited
• Can get some timing differences (see Ulfs
  Method)
• But will have a large constant error
• Network traffic during study

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Server-Side Software

• Perl http//www.perl.com./
• PHP http//www.php.net/
• Generic PHP Form Processor http//www.goeritz.net
  /brmic/
• MySQL http//www.mysql.com/

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Client-Side Solutions

• Program runs on participants computer
• Allows direct control of participants computer
• Usually requires some plugin or interpreter to be
  present on the participants computer

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JavaScript

• A scripting language interpreted in client
  browser
• Requires a scripting interpreter in the browser
• Is an object-orienting scripting language
• Viewers of the page can get the program
• Is not related to Java though some similarity in
  commands
• Installed on most browsers but some people turn
  off or limit

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JavaScript Editors

• JavaScript Editor Lite http//www.yaldex.com/JSFa
  ctory.htm
• JSEclipse (plugin for Eclipse)
  http//www.interaktonline.com/Products/Eclipse/JSE
  clipse/Overview/

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Java

• Object-Oriented Program Language
• Partially compiled/Partially interpreted
• Allows for more platform independence
• Runtime engines are written for each environment
• But it does change
• Comes with most browsers now and lot of other
  software
• But several versions exist
• Microsofts version is disappearing (YEAH!)

22
Some Java Limitations

• Java is limited, partly to make web safe
• Cannot sync drawing to beginning of frame
• An example
• Timing is problematic (low priority and difficult
  to steal priority from other machine operations)
• Eichstadt (2001) gives way to handle timing issues

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An Example of Java Timing
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Writing in Java

• Eclipse http//www.eclipse.org/
• An open source Integrated Development Environment
• Java not used much due to complexity
• Need an experiment library

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Adobe Plugins (formerly Macromedia)

• Flash/Authorware (http//www.adobe.com)
• These are really high level languages with
  specially designed IDEs
• They require special plugins/players to run
• Flash usually preinstalled on most browsers
• Others less likely
• Support for Shockwave/Authorware on wane
• Flash is being pushed by publishers

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Adobe Software

• Flash http//www.adobe.com/products/flash/
• Authorware http//www.adobe.com/products/authorwa
  re/
• Authorware used at the PsychExps site
• Largely basis of experiments at Online Psychology
  Laboratory (OPL) by American Psychological
  Association (http//opl.apa.org)

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Client-Side Summary

• Advantages

• Disadvantages

• Greater control over participants computer
• Can increase interactive aspects of experiment
• Less need to communicate with server during
  experiment

• Requires plugin which participant may not have
• Greater impact of participants setup
• Participants may turnoff ability to run plugin
• May require large download to run
• Not all timing issues have been solved

28
Learning Curve vs. Power
Learning Curve Learning Curve Learning Curve
Shallow Medium Steep
Power Low HTMLForms
Power Medium PerlPHPJavaScript
Power High Flash AuthorwareJava
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Some Additional Issues to Consider

• Who can and will use the media?
• Who cannot or will not use the media?
• Issues of external vs. internal validity
• Will this impact my results?
• Will usage depend upon condition?
• If download time or complexity varies depending
  upon condition you have a confound

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Conclusion

• Test! Test! Test!
• Browser bugs!
• Consider is the web the best choice not the
  easiest choice