FAQ: Missing Applet

Why does my browser say "This JavaSketch may be unusable because the applet file (jsp5.jar) appears to be missing from its proper location. " when I view a Web page with JavaSketchpad illustrations?

In order for a JavaSketchpad construction to be properly viewed on a Web page, your browser must be able to locate on the web server both the HTML file containing the page’s text, as well as a separate applet file, jsp5.jar, which contains the JavaSketchpad software. This error appears when your browser can locate the first but not the second. Usually this results from a misconfiguration of resources on the web server, and can only be resolved by the creator of the web page you are trying to reach. Please send him or her an e-mail citing the error you encounter, and reference this FAQ for a detailed explanation of how to fix it.

If you are the creator or webmaster of a JavaSketchpad-enhanced web page or web site, seeing this error on a given web page indicates that the jsp5.jar applet file is no longer at the URL specified in the parameter in your web page’s HTML. (This is usually a URL that is relative to the HTML page itself on your server.)  The most typical configuration is for the jsp5.jar file to be stored next to (in the same directory) as the HTML file itself.  This is the configuration assumed by The Geometer’s Sketchpad when automatically “exporting” constructions to HTML and JavaSketchpad. In this configuration, the easiest solution is to assure that a copy of jsp5.jar is placed next to every HTML file that you want to view, whether this file is located on your hard drive or on a Web server. That is, if you have a folder called "Sketches" which contains a JavaSketch called "MySketch.html," then the folder "Sketches" must also contain a copy of jsp5.jar.

For users who are comfortable with editing HTML files, note it is possible for the HTML file to refer to an applet file stored in a separate directory. The CODEBASE parameter is set to "." by default, meaning that the applet is expected to be in the same directory as the HTML. This parameter can be altered to refer to a relative or absolute path, allowing for multiple JavaSketches in different folders to refer to the same single applet file without copying it into every folder. Additionally, the entire contents of the SCRIPT tag are dedicated to finding the applet and displaying an error if it is not found. All of this should be deleted if the CODEBASE parameter is manually altered, because this script code will continue to look for the applet in the same directory as the HTML file, which could result in the error appearing even though the JavaSketch is rendered properly.