Java Web Start

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Java Web Start or Oracle Web Start is a tool for transferring Java applications over the Internet and getting started with just one click. In contrast to Java applets , Java Web Start applications do not need a browser to run. The tool is based on the JNLP standard .

The manufacturer Oracle has discontinued Web Start : Web Start is no longer included in the current LTS Java Version 11. Since Web Start was never developed as open source in the OpenJDK, but was always added as closed source software by Oracle when building their Java distribution, there was no alternative Java distribution to the use of Web Start for a long time. The last long-time support version with Web Start is the Java 8 distribution from Oracle. Oracle recommends the not directly comparable packaging tool jlink as a replacement. For many users, however, jlink is not a sufficient substitute. B. There is no jlink for Java version 8 and features such as update functionality are missing. For this reason, various companies and organizations such as AdoptOpenJDK or RedHat have come together to provide an open source solution as a replacement for Java Web Start.

Each time a Java Web Start application is started, it can be checked whether there are newer components and whether there is a current Java runtime system in the target computer. In this way, the user can always work with the current version supplied by the program author. Once a version of an application has been downloaded, it remains in a cache on the client's hard drive until the check detects that a new version is available and that it has to be loaded. This prevents unnecessary downloads and still ensures that the current program version is always running.

The prerequisite for the execution of Java Web Start applications is that

  • the developer offers the program for download on a server and provides a special XML file (with the ending " .jnlp") in which the individual components of the application are described.
  • the web server on which the Java application is provided knows the MIME type application / x-java-jnlp-file .
  • The Java Runtime Environment is installed on the client (JRE contains Java Web Start version 1.4.2 or higher), since the Java application is executed with the help of the local Java VM .

Successor to Java Web Start

The AdoptOpenJDK community with the support of the company RedHat started and Karakun, an open source to develop and provide an alternative to Java Web Start. The whole thing is developed in GitHub under the AdoptOpenJDK organization. The development is based on IcedTea-web, which was mainly developed by RedHat as part of IcedTea . The AdoptOpenJDK project tries to increase the quality of IcedTea-Web, to remove errors and to submit non-implemented features of the JNLP standard or Oracle Web Start.

Based on IcedTea-Web, the Karakun company provided the open source tool OpenWebStart . This takes over the functionality of IcedTea-Web and extends it with many native and extended features. In addition, OpenWebStart offers native installers for Mac OS , Windows & Linux . This tool was also created with the support of RedHat and AdoptOpenJDK.

Java Network Launching Protocol (JNLP)

The Java Network Launching Protocol (JNLP) requires a configuration file in XML format for each application . These JNLP files contain information on the storage location of JAR files , the name of the main class of an application and other parameters for the program to be called. A configured web browser transfers JNLP files to the Java runtime environment , which then downloads and starts the application on the user's PC. JNLP was developed in the Java Community Process as JSR -56.

See also

The ClickOnce concept of the .NET framework from Microsoft offers a similar functionality for Windows programs.

Individual evidence

  1. ↑ JDK 9 Release Notes. Deprecated APIs, Features, and Options. Oracle, accessed July 5, 2018 .
  2. ↑ Hendrik Ebbers: Java WebStart Is Dead: What Should We Do Now? October 23, 2018, accessed June 18, 2020 .
  3. ↑ Oracle Java SE Support Roadmap. Oracle, June 28, 2018, accessed July 5, 2018 .
  4. ↑ Java Client Roadmap Update. To Oracle White Paper. March 2018, accessed on July 5, 2018 .
  5. ↑ JEP 220: Modular Run-Time Images. Retrieved June 18, 2020 .
  6. ↑ Jayashree Kumar: Using IcedTea Web Browser Plug-in with AdoptOpenJDK. In: AdoptOpenJDK. October 4, 2018, accessed May 31, 2019 .
  7. ↑ OpenWebStart. Retrieved June 18, 2020 .
  8. ↑ hendrik: How open source saved WebStart. December 10, 2019, accessed June 18, 2020 .
  9. ↑ Java (TM) Network Launching Protocol & API Specification (JSR-56): Version 1.5 . Java Software: A Division of Sun Microsystems, Inc., May 21, 2001 ( java.sun.com [accessed December 23, 2006]).

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