What is the download JAR file for Java?
Download java-util-1.3.1.jar The download jar file contains the following class files or Java source files.
What JAR files does the new Java plug-in look for?
The New Java Plug-in will look for HelloWorld.jar.pack.gz, if this file is not available, it will fall back and look for HelloWorld.jar. Version download is the ability to request that specific versions of certain jar files be used by applets and Java Web Start applications.
How to find the compressed version of a JAR file?
When the Java system property jnlp.packEnabled is set to "true" in a jnlp file or an applet tag, the Java Plug-in or Java Web Start software will download the .pack.gz version of JARs. If the .pack.gz version is not available, the unzipped JAR will be searched for. Note: the compressed version of foo.jar should be named foo.jar.pack.gz.
Can I deploy versioned or Pack200 compressed jars on Java Server?
While this solution works, it limits the flexibility of deploying versioned or Pack200 compressed JARs: Engineers might not have access to deploy JNLPDownloadServlet on web servers. The Java SE 6 update 10 release introduces two new Java system properties to enable Pack200 and version download: jnlp.packEnabled and jnlp.versionEnabled.
Introduction
Prior to Java SE 6 update 10 release, engineers had to deploy the JNLPDownloadServlet on the web servers in order to use Pack200 or download specific versions of their application JARs.
Pack200
When the Java system property jnlp.packEnabled is set to "true" in a jnlp file or an applet tag, the Java Plug-in or Java Web Start software will download the .pack.gz version of JARs. If the .pack.gz version is not available, the unzipped JAR will be searched for.
Version Download
Version download is the ability to request that specific versions of certain jar files be used by applets and Java Web Start applications. The jnlp.versionEnabled applies to Java Web Start applications and applets deployed using JNLP.