APPLET CACHING IN JAVA PLUG-IN 1.3.1

Introduction

Applet caching ensures that applets are not unnecessarily downloaded by a browser every time a user references them. 

Java Plug-in has supported disk caching in previous versions by using the same cache the browser uses for all other web documents. This works for casual applet usage, but larger applets can often get flushed from the cache to make room for other documents since the browser has no knowledge that an applet file might be needed in the future. The result is that this caching strategy fails where is needed most in large business applets.

This release introduces an alternative form of applet caching which allows an applet deployer to decide whether applet should be "sticky", that is, to stay on the disk in a secondary cache which the browser cannot overwrite. The only time "sticky" applets get downloaded after that is when they are updated on their server. Otherwise the applet is always available for quick loading. We recommend that applets which provide core business applications be made sticky to improve their startup performance.

How to delete the Cached Plug-in Files

With the JAR caching feature (available since 1.3), redundant downloads can be avoided and applets can be run offline. But since a user may want to delete the cached files at some time, an option exists in the Java Plug-in Control Panel for deleting the cached files. A user can push the "Clear JAR Cache" button to delete the JAR cache. Next paragraph describes how the user can force reloading the applet (jar) file by deleting the Plug-in cache.

Note: The applet (jar) file is automatically re-loaded when the file is updated on the server, regardless of the user action in the Plug-in's Control Panel. 

Java Plug-in Control Panel is accessible from the Windows Control Panel (Start/Settings/Control Panel). Find the Java Plug-in icon:

double click this icon and the Java Plug-in Control Panel will open. Go to the Cache tab, click on the "Clear JAR Cache" button and OK at the message. After doing that close the Plug-in Control Panel from the X button on the right top corner. In order to reload the applet from the server you need to restart the browser.