Java[tm] Web Start Installation Guide


Installation Guide

Java TM Web Start

Version 1.2


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This installation guide provides documentation for the system requirements and installation instructions for this release of Java Web Start.

Table of Contents

System Requirements
Upgrading from Previous Versions
Installing on Microsoft Windows
Installing on Solaris/Linux
Using Java Web Start with Netscape 6/6.01
Troubleshooting the Installation

System Requirements

This release of the Java Web Start product can be run on version 1.2.2 or later of the J2SE TM platform. The hardware and operating system requirements for using Java Web Start are the same as those recommended for J2SE platform implementation on which it runs.

Java Web Start will not work with any version of the JDK 1.1.x software, or earlier versions.

Upgrading from Previous Versions

Do not uninstall your previous version of Java Web Start (if you have one) before installing the new version. Uninstalling the previous version will cause the download cache to be cleared, and all of the previously installed Java Web Start applications will have to be downloaded again. This new release will overwrite previous installations and automatically update browsers to use this new release. If you want to reactivate a previous version after installing this new release, you will have to re-install the old version.

The configuration files and program files folder used by Java Web Start have not changed, so all your settings will remain intact after the upgrade.

Installing on Microsoft Windows

Then locate and execute the installer, javaws-1_2-windows-i586-i.exe, by double-clicking on its icon. The installer program will guide you through the installation. The installer prompts for the installation directory (default is c:\Program Files\Java Web Start).

The installer looks in the Windows Registry for already installed Java Runtime Environments, version 1.2.2 and higher, and automatically configures Java Web Start to use them. If a Java Runtime Environment of at least version 1.2.2 is not already installed on the system, the installer will install a Java Runtime Environment after installing the Java Web Start software.

The installation registers the file extension .jnlp and the MIME type application/x-java-jnlp-file with Windows, so Java Web Start will be launched from both Netscape Navigator and Internet Explorer (and most other browsers) when a link to a JNLP file is activated. The installer also installs shortcuts to the Application Manager on the desktop and in the Windows Start menu.

Installing on the Solaris TM Operating Environment and Linux

For the Solaris Operating Environment and for Linux, Java Web Start is delivered as a ZIP file. The ZIP file contains the installation shell script,, along with the readme.html file.

Move the ZIP file to a location where you want to install Java Web Start (preferably outside the Java 2 SDK or Java Runtime Environment installation). Unzip the file and execute the Java Web Start install script, After you agree to the terms of the license it displays, the script will prompt you for the location of a Java runtime environment if it doesn't find one in the default location of /usr/local/java.

The installer will create the javaws subdirectory and install all the Java Web Start files into it.

The installer also updates the .mailcap and .mime.types files, so Java Web Start will be invoked when Netscape Navigator encounters a link to a JNLP link. On the Solaris Operating Environment, it installs hooks into CDE so double-clicking on .jnlp files in the File Manager will also launch Java Web Start.

Make sure to restart Netscape to ensure that it picks up the new MIME type.

Using Java Web Start with Netscape 6/6.01

For Netscape 6/6.01 users, please setup the Java Web Start MIME type (JNLP) in the Edit->Preferences->Navigator->Helper Applications section. The file extension is "jnlp", MIME Type is "application/x-java-jnlp-file", and it should be handle by the javaws executable file in your Java Web Start directory.

Also note that you must use the non-javascript version of the demos page, due to a problem with the Javascript with Netscape 6/6.01. For more information please refer to the developer's guide.

Troubleshooting the Installation

If you see an error message " Error opening file for writing" during installation:


This message is usually displayed when trying to install while an existing version of Java Web Start is running. If you see this message, it is recommend that you close all existing instances of Java Web Start applications, and click 'Retry'. If this does not solve the problem, you must reboot and run the install again.


If Java Web Start prints out a bad installation error message:


This may mean that Java Web Start has not been configured with the right information about your JRE locations. Check the contents of the javaws.cfg file. It will be in the installation directory of Java Web Start (typically at C:\Program Files\Java Web Start\javaws.cfg on Windows).

These configuration entries need to reflect the locations of the Java 2 SE JRE installations on your system. For example:


Modify this file to reflect your system configuration by adding, removing, or deleting javaws.cfg.jre.<n>.location, javaws.cfg.jre.<n>.path, javaws.cfg.jre.<n>.platform and javaws.cfg.jre.<n>.product entries. Make sure that the javaws.cfg.jre.default=<n> refers to an existing entry. Entries are numbered consecutively starting at 0.

Java Web Start will not work with any version of the JRE 1.1.x software, or earlier versions.


  Copyright © 2002, Sun Microsystems, Inc.
All rights reserved.

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