Resurrecting Applets

1. Resurrecting Applets Eric Roberts Professor of Computer Science, Stanford University ACM Java Task Force Chair SIGCSE 2007 Symposium Covington, Kentucky March 10, 2007

2. 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

3. 1. 2. 3. 4. 5. Object-oriented approach. Backward compatibility. In order to be forward-looking and to ensure that our resources remain current for as long as possible, our baseline version of Java will be Standard Edition 1.5. However, we anticipate that some institutions will not be in a position to adopt Java 1.5, even by the time at which the Task Force materials are released. For this reason, we will make every effort to ensure that those resources work in Java releases from Java 1.2 forward. Minimalism. Conformance. Multiple environments. Principles

4. This situation, however, did not last. Java applets fueled Java’s initial growth. The ability to download code over the network and run it on a variety of desktops offering a rich user interaction proved quite compelling. However, Java’s Write Once, Run Anywhere (WORA) promise soon became strained as browsers began to bloat and several incompatibilities emerged that were caused by the Java language itself. —Raghavan N. Srinivas, Java World, 2001  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 hasn’t 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)  

5. Java 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 anyone—faculty and browser manufacturers alike—to 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.

6. 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.

7. Hi. I was wondering if you could tell me how to put the programs I’ve written online so that they can be run as applets so that my friends/parents can run them. Thanks. -- Brittney Brittney, A long four-point process showing how it was done at the time. It should all work. -- Eric Brittney Fraser Secretary SBSE CS major section leader Fantastic! 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:

8. Applets Are Not Going Away The good news is that applets are extremely unlikely to disappear entirely, mostly because doing so is not in anyone’s 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.

9. 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 world—your local Kinko’s, the massive EasyInternetCafe outlets, a coffee shop that has a few machines—that 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

10. 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 didn’t 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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