Monday, 28 May 2012

Java: JVM Inside .A story behind JVM.

The word JVM is the core heart of java programming language. It stands for Java Virtual Machine , a simple virtual machine inside your physical computer/system. The virtual refers to not physically it is conceptual.So, it is a virtual machine which can understand byte code.

It is the code execution component of java software platform.A Java virtual machine is software that is implemented on virtual and non-virtual hardware and on standard operating systems. A JVM provides an environment in which Java byte code can be executed, enabling such features as automated exception handling, which provides root-cause debugging information for every software error (exception), independent of the source code. A JVM is distributed along with a set of standard class libraries that implement the Java application programming interface (API). Appropriate APIs bundled together with JVM form the Java Runtime Environment (JRE). 

The term WORA (Write Once and Run Anywhere) make java popular & easy . JVM understand byte code which is the intermediate language between programming and system.The WORA  and   write once, compile anywhere,(WOCA)  which describes cross-platform compiled languages Thus, the JVM is a vital component of the java platform. Typically , we can say JVM makes java platform independent. 


                                                 Java Source File (.java)
                                                                  |
                                                                  |
                                                   Java Compiler ( javac)     
                                                                  |
                                                                  |
                                       Byte code ( .class file, secure code)    
                                        |                         |                         |
                                        |                         |                         |
                                     JVM                   JVM                  JVM
                                       |                          |                         |
                                       |                          |                         |
                                Windows                Linux                   Mac

                                                                                                         Continue to read this in next post