Java Virtual Machine (JVM)
Java Virtual Machine (JVM) is a hypothetical machine over which Java code runs. It provides an interpreter used for execution of the compiled Java code (Java byte code). Java Byte code is special kind of machine language which could be run on any platform provided a JVM compatible to that platform is installed on that. It also makes Java platform independent (Write Once Run Everywhere).
SAP delivers its own Java Virtual Machine (JVM) with SAP NetWeaver 7.1 release and is is called SAP JVM. It is developed for robust, scalable and high performing SAP NetWeaver Application Servers and It offers a very strong and reliable foundation for the whole SAP NetWeaver Java stack. For the features of new Java EE 5 environment refer weblog – What’s New in JEE 5 ?..
The SAP JVM is included in all products based on the NetWeaver Application Server Java 7.1. It resides in the sapjvm_5 folder located in the foloder /usr/sap/(SID)/exe/run.
This virtual machine is certified and fully compliant with the Java SE 5 standards.
To know more about Java terms please refer the weblog – Introduction to Java Standard Edition 5.0 Terminologies
JVM also takes care of Garbage collection in a separate Threads in Java which is responsible for freeing any unused memory. This happens automatically during the execution of the Java program freeing programmer from the burden of having to deallocate that
memory themselves. For details of multithreading in Java refer weblog – What is Multithreading ?
for more details about Java Garbage Collector check the weblog on – Introduction to Garbage Collector
If you do not use a SAP NetWeaver Application Server Java 7.1 you can still download and install the SAP JVM as a stand-alone.
SAP customers can download the official versions of SAP JVM from the SAP Service Marketplace (http://service.sap.com). The SAP JVM 5 is available for all operating system platforms supported by SAP NetWeaver 7.1.
Please find it in the Software Distribution Center and select “SAP Support Packages > Support Packages and Patches > Entry by Application Group > SAP NetWeaver > SAP NETWEAVER > SAP NETWEAVER CE 7.1 EhP1 > Entry by Component > Java Application Server > SAP JVM 5.1”.
Please view the video in the link below for steps to download SAP JVM.
NetWeaver AS Tools
Java programs running over SAP JVM can also be profiled (analyzed for memory consumption and response time) using SAP JVM Profiler.
More tools for NetWeaver Application Server – Java are available in the following link: Tools for Application Server