Oracle JRockit provides tools, utilities, and a complete run-time environment for developing and running Java applications. JRockit JDK includes the Oracle JRockit JVM, which is developed and optimized for Intel architectures to ensure reliability, scalability, and manageability for Java applications.
This chapter contains information about the following topics:
Section 1.3, "Supported Configurations for the Oracle JRockit JDK"
Section 1.5, "Compatibility Between JRockit JDK and HotSpot"
The JRockit JVM is a high-performance JVM developed to ensure reliability, scalability, manageability, and flexibility for Java applications. The JRockit JVM provides improved performance for Java applications deployed on Intel 32-bit (Xeon) and 64-bit (Xeon and SPARC) architectures at significantly lower costs to the enterprise. Further, it is the only enterprise-class JVM optimized for Intel architectures, providing seamless interoperability across multiple hardware and operating system configurations. The JRockit JVM enables your Java applications to run optimally on Windows and Linux operating systems (both 32-bit and 64-bit architectures). The JRockit JVM is especially well-suited for running Oracle WebLogic Server.
For more information about JVMs, see The Java Virtual Machine Specification at: http://java.sun.com/docs/books/jvms/second_edition/html/VMSpecTOC.doc.html
The JRockit JVM is one component of the JRockit JDK JDK. In addition to the JRockit JVM, the JDK contains the Java Run-time Environment (JRE). The JRE contains the Java class libraries (as specified by the Java Platform, Standard Edition 6 API Specification) and a set of development tools, such as a compiler.
For more information about the contents of the JRockit JDK, see Section 1.6, "Contents of a JRockit JDK Installation".
Every JRockit JVM release comes with several Java versions. For example, JRockit JVM R28.0 comes with Java SE versions 5.0 and 6. A Java version can be compatible with multiple JRockit JVM releases.
The JRockit JDK release number consists of the following elements:
The JRockit JVM release number (Rnn.nn.nn)
The Java version (J2SE 5.0 or Java SE 6)
For example, Oracle JRockit JDK 6 R28.0.0 indicates the 28.0.0 release of JRockit JVM used with Java SE 6; similarly, Oracle JRockit JDK 5.0 R28.0.0 indicates the 28.0.0 release of the JRockit JVM used with J2SE 5.0.
The following is an example of a complete release number:
R28.0.0-637-126675-1.6.0_17-20100111-2121-windows-ia32
In this example, R28.0.0 is the JRockit JVM release, 1.6.0_01 is the Java version, and windows-ia32 is the platform on which the release runs.
Oracle JRockit JDK is compatible with J2SE 5.0 and Java SE 6.
For a full list of processor types and operating systems that JRockit JDK supports, see Oracle JRockit JDK Supported Configurations at http://www.oracle.com/technology/software/products/ias/files/fusion_certification.html.
The Oracle Lifetime Support Policy for Oracle Fusion Middleware is available at http://www.oracle.com/support/library/brochure/lifetime-support-middleware.pdf.
The Software Error Correction Policy is available in Support Note ID 950131.1.
All Java APIs follow the Java compatibility statement (http://java.sun.com/javase/6/webnotes/compatibility.html).
Official APIs (JMAPI, JRockit JMX beans) cannot be removed or modified except between major JDK versions. New APIs can be added at any time.
Unofficial but supported APIs (jrockit.ext.*) cannot be removed in service packs.
Internal APIs (all jrockit.* except for jrockit.ext.*) can change at any time.
Standard options (for example, -server) adhere to the Java compatibility statement (http://java.sun.com/javase/6/webnotes/compatibility.html).
Nonstandard -X options adhere to the Java compatibility statement (http://java.sun.com/javase/6/webnotes/compatibility.html).
Nonstandard -XX options are handled as follows:
They cannot be removed unless in association with major JDK updates.
They can be disabled or their implementation can be changed at any time.
New -XX options can be added at any time.
The JRockit JDK is similar, in the file layout, to the HotSpot JDK, except that the JRockit JDK includes a new JRE with the JRockit JVM. All of the class libraries have the same behavior in the JRockit JDK as in the HotSpot JDK.
Table 1-1 describes the contents of the directories in a JRockit JDK installation.
Table 1-1 Contents of a JRockit JDK Installation
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The The JRockit JDK includes the standard tools distributed with the typical Java JDKs. Most of these tools work well with Java development projects, but you can use any other third-party tools, compilers, debuggers, IDEs, and so on that work best in your situation. The tools included with the JRockit JDK are:
For more information about these tools, see the documentation at |
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The Java Virtual Machine: By definition, the JVM is the JRockit JVM, as described in this documentation. Standard Java SE JRE Features: In addition to JRE components specific to the JRockit JDK, the JRE also contains components found in the HotSpot implementation of the JRE. For a complete list of the standard Java SE JRE features, see the following documentation:
Note about JRE class files: The JRE class files distributed with the JRockit JDK are the same as those in the HotSpot JDK, except for a small number of files that are tightly coupled to the JVM and are, therefore, overridden in the JRockit JDK. No classes are omitted. |
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The JRockit JVM configuration and tuning parameters are set by using specific command-line options, which you can enter either along with the start-up command or include in a start-up script.
For more information, see the Oracle JRockit Command-Line Reference.