Resurrecting Applets

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Resurrecting Applets
Eric Roberts Professor of Computer Science,
Stanford University ACM Java Task Force Chair
SIGCSE 2007 Symposium Covington, Kentucky March
10, 2007
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The ACM Java Task Force
The ACM Java Task Force was established in early
2004 with the following charter
To review the Java language, APIs, and tools from
the perspective of introductory computing
education and to develop a stable collection of
pedagogical resources that will make it easier to
teach Java to first-year computing students
without having those students overwhelmed by its
complexity.
The Task Force released Version 1.0 of its
materials in August.
http//jtf.acm.org
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Principles
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The Rise and Fall of the Applet Paradigm
In the early years of Java, applets were
responsible for much of the tremendous excitement
associated with the language.
Anyone using a computer who hasnt been in a cave
for the last year has heard of Java applets. Many
people believe that Java is useful only for
applets.
K. Mitchell Thompson. Tips and techniques for
Java  (in Dwight, Irwin, and Niles, Using CGI,
1997)  
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The Pace of Change
The biggest challenge involved in keeping applets
running lies in keeping up with the changes in
Java. Java evolves rapidly, and it is
difficult for anyonefaculty and browser
manufacturers aliketo keep up. Moving toward
plug-in strategies provides some insulation from
the changes, but the user is still responsible
for keeping those plug-ins current.
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Applets Are Incredibly Useful
The decline in the practicability of applets is
unfortunate, because they turn out to be
incredibly useful

• Applets make it easier for people developing
  educational tools to demonstrate their software
  on the web. The programs in the JTF Demo Gallery
  all run as applets on the web.
• The ability to save programs as applets allows
  instructors to make interactive classroom demos
  easily available to students.
• Having all student programs run as applets make
  it much easier for students to share their
  accomplishments with their families and friends
  at other schools.

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Reach Out and Touch Someone
Students love the ability to put their work on
their web site. Consider the following e-mail
exchange with a student last year
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Applets Are Not Going Away
The good news is that applets are extremely
unlikely to disappear entirely, mostly because
doing so is not in anyones interest.

• Removing applet functionality makes it impossible
  to view web pages that use them, which would in
  turn make those browsers less popular.
• Taking out the code to support applets requires
  work. Browser developers would surely prefer to
  invest that effort in developing new features.

At the same time, the fact that relatively few
people are writing new applets that depend on
newer releases of Java means that developers have
no real incentive to keep current.
The bottom line is that applets will continue to
run as long as one is willing to maintain
compatibility with old versions of Java.
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How Old Is Old?
It is staggering, however, how old the stable
Java standard is. If you walk into essentially
any Internet storefront anywhere in the
worldyour local Kinkos, the massive
EasyInternetCafe outlets, a coffee shop that has
a few machinesthat machine will likely be
running the JDK 1.1 release of the Java runtime.
That means

• No Swing
• No collections framework
• No Java 5.0 generics
• No Scanner class
• Reduced functionality in many classes

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Outline of Our Strategy

• At no time did the Java Task Force ever propose
  that students would write in anything other than
  the latest version of Java.

• Initially, we had tried to write the libraries
  themselves using JDK 1.1 so that it would be
  possible to load them on older browsers.
• We abandoned that strategy for the reasons I cite
  in the paper
• The code was too difficult to maintain
• Our code could not serve as a model for students
• Many people somehow believed that it was possible
  to use the ACM Java Libraries only with older
  versions of Java
• It didnt actually solve the problem
• What we did instead is create an acm11.jar
  library that reimplements the features from the
  JDK subset using the JDK 1.1 model.

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The End