Documentation Java Beat

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==Java==
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=== Best of Breed Free Software Java implementation ===
 
  
Fedora includes best of breed free software java implementations through active adoption of innovative Fedora and upstream technology integration. The implementations integrated into Fedora are based on [http://openjdk.java.net/ OpenJDK] and the [http://icedtea.classpath.org/ IcedTea] GNU/Linux distribution integration project or alternatives like the GNU Compiler for Java ([http://gcc.gnu.org/java GCJ]) and the [http://www.gnu.org/software/classpath/ GNU Classpath] core class libraries. All Fedora innovations are pushed upstream to get the widest possible integration of the technologies in general Java implementations.
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[[Category:Docs Project]]
 
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[[Category:Draft documentation]]
The implementation of OpenJDK 6 included in Fedora 10 uses the HotSpot virtual machine runtime compiler on x86, x86_64 and sparc. On ppc it uses the zero interpreter (which is a bit slower). On all architectures an alternative implementation based on GCJ and GNU Classpath is included which includes a ahead of time compiler to produce native binaries.
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[[Category:Documentation beats]]
 
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Fedora binaries for selected architectures (currently only x86 and x86_64 based on OpenJDK) are tested against the Java Compatibility Kit (JCK) by Red Hat to guarantee 100% compatibility with the Java Specification (JDK 1.6 at this time).
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=== Handling Java Applets and Web Start Applications ===
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In Fedora 10 <code>gcjwebplugin</code> has been replaced by <code>IcedTeaPlugin</code> that runs untrusted applets safely in a Web browser. You can see which Applet Plugin is installed by typing <code>about:plugins</code> in firefox. The new plugin adds support for the JavaScript bridge (LiveConnect) which was missing from earlier versions [https://bugzilla.redhat.com/show_bug.cgi?id=304021 bytecode-to-JavaScript bridge (LiveConnect)]. The plugin works on any architecture.
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Feedback on the security policy is much appreciated. If you suspect the security policy may be too restrictive to enable restricted applets, then run the <code>firefox -g</code> command in a terminal window to see what is being restricted, and then grant the restricted permission in the <code>/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0/jre/lib/security/java.policy</code> file and/or report a bug.
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Experimental Web Start (<code>javaws</code>) support via [http://jnlp.sourceforge.net/ NetX] has been added to the IcedTea repository. When a Java Network Launching Protocol (<code>.jnlp</code>) file is embedded on a web page you can open it with the IcedTea Web Start (<code>/usr/bin/javaws</code>).
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=== New integration with other Fedora technologies ===
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Through the IcedTea project OpenJDK has been integrated with a couple of new technologies that are also part of Fedora 10:
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==== VisualVM integration through the NetBeans framework ====
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VisualVM (<code>jvisualvm</code>) provides a graphical overview of any local or remotely running java application and lets you monitor all running threads, classes and objects allocated by the application by taking thread dumps and heap dumps and other lightweight profiling tools.
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==== PulseAudio integration for javax.sound ====
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PulseAudio integrations provides all the benefits of PulseAudio to any java application using the <code>javax.sound</code> package.
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==== Integration of the Mozilla Rhino (javascript) ====
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Rhino is a pure java javascript implementation from Mozilla providing easy mixing of Java and JavaScript for developers using the <code>javax.script</code> package.
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==== Other improvements ====
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Also in Fedora 10 Java cryptography (<code>javax.crypto</code>) is fully supported without any (regional) restrictions.
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=== Fedora and JPackage ===
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Fedora 10 includes many packages derived from the [http://jpackage.org JPackage Project] .  Some of these packages are modified in Fedora to remove proprietary software dependencies, and to make use of GCJ's ahead-of-time compilation feature.  Use the Fedora repositories to update these packages, or use the JPackage repository for packages not provided by Fedora.  Refer to the [http://jpackage.org JPackage website] for more information about the project, and the software it provides.
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Admonition("warning", "Mixing Packages from Fedora and JPackage", "Research package compatibility before you install software from both the Fedora and JPackage repositories on the same system.  Incompatible packages may cause complex issues.")
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=== Note on upgrading from Fedora 8 - OpenJDK Replaces IcedTea ===
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Since Fedora 9 the packages called <code>java-1.7.0-icedtea*</code> in Fedora 8 have been renamed to <code>java-1.6.0-openjdk*</code>. The Fedora 8 IcedTea packages tracked the unstable OpenJDK 7 branch, whereas the <code>java-1.6.0-openjdk*</code> packages track the stable OpenJDK 6 branch. All the upstream IcedTea sources are included in the java-1.6.0-openjdk SRPM.
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If you are upgrading from a system based on Fedora 8 that still has IcedTea installed, the package changeover does not happen automatically.  The packages related to IcedTea based on OpenJDK 7 must first be erased, then the new OpenJDK 6 packages installed.
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<pre>
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su -c "yum erase java-1.7.0-icedtea{,-plugin}"
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su -c "yum install java-1.6.0-openjdk{,-plugin}"
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</pre>
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Upgrading from Fedora 9 doesn't need any special action.
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Revision as of 06:24, 19 July 2013

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