Futuristic Technologies

08/03/2022

Rajyalakshmi Reddi, the first woman telecommunications engineer in India, was the sole female in her batch.
On graduation, she joined Indian Telephone Industries, Bangalore, but in November 1948 moved to All India Radio, Delhi, as a sound engineer in the control room. It was an opportunity to work on the technical aspects of recording personalities like Jawaharlal Nehru and Lata Mangeshkar.
In the 1970s, she was deputed as principal of Hyderabad's Kamala Nehru Polytechnic for Women. There she added garment technology to the existing courses, which included engineering, architecture, computer science, commerce, hotel management and catering, and pharmacy, making herself familiar with all of them.
Later, she returned to AIR in 1976, retiring five years after serving as the Assistant Station Engineer.

13/08/2013

12/08/2013

Evolution:

12/08/2013

Difference between JRE, JVM & JDK .

Have you ever wondered working on an Java Environment what are the jargons JRE, JDK & JVM on which we work daily. But are we cognizant about them 100% ?

Java Runtime Environment (JRE)

Java is every where in browser, in mobile, in TV or in set-top boxes and if you are into Java programming language than you know that Java code which is bundled in JAR (Java archive) file require Java virtual machine JVM to execute it. Now JVM is an executable or program like any other program and you can install that into your machine. You have seen browser often suggesting download JRE to run a Java Applet downloaded from Internet. Various version of JRE are available in java.oracle.com and most of the user who just want to execute Java program inside browser or standalone downloads JRE. All browsers including Internet Explorer, Firefox and Chrome can work with JRE.

Java Virtual Machine (JVM)

When you download JRE and install on your machine you got all the code required to create JVM. Java Virtual Machine is get created when you run a java program using java command e.g. java HelloWorld. JVM is responsible for converting byte code into machine specific code and that's why you have different JVM for Windows, Linux or Solaris but one JAR can run on all this operating system. Java Virtual machine is at heart of Java programming language and provide several feature to Java programmer including Memory Management and Garbage Collection, Security and other system level services. Java Virtual Machine can be customized e.g we can specify starting memory or maximum memory of heap sizelocated inside JVM at the time of JVM creation. If we supplied invalid argument to java command it may refuse to create Java Virtual Machine by saying "failed to create Java virtual machine: invalid argument". In short Java Virtual Machine or JVM is the one who provides Platform independence to Java.

Java Development Kit (JDK)

JDK is also loosely referred as JRE but its lot more than JRE and it provides all the tools and executable require to compile debug and execute Java Program. Just like JRE, JDK is also platform specific and you need to use separate installer for installing JDK on Linux and Windows. Current Version of JDK is 1.7 which is also referred as Java7 and it contains javac (java compiler) based on programming rules of Java7 and Java which can execute java7 code with new features like String in Switch, fork-join framework or Automatic Resource Management. When you install JDK, installation folder is often referred as JAVA_HOME. All binaries are located inside JAVA_HOME/bin which includes javac, java and other binaries and they must be in your system PATH in order to compile and execute Java programs. For details on Path see how to set PATH for Java in Windows and UNIX.

Difference between JRE, JDK and JVM

In short here are few differences between JRE, JDK and JVM:

1) JRE and JDK come as installer while JVM are bundled with them.
2) JRE only contain environment to execute java program but doesn’t contain other tool for compiling java program.
3) JVM comes along with both JDK and JRE and created when you execute Java program by giving “java” command.

Just in Time Compiler (JIT)
Initially Java has been accused of poor performance because it’s both compiles and interpret instruction. Since compilation of Java file to class file is independent of ex*****on of Java program do not confuse. Here compilation word is used for byte code to machine instruction translation. JIT are advanced part of Java Virtual machine which optimize byte code to machine instruction conversion part by compiling similar byte codes at same time and thus reducing overall ex*****on time. JIT is part of Java Virtual Machine and also performs several other optimizations such as in-lining function.

That’s all on JRE, JDK and Java Virtual machine and difference between them. Though they look similar they are different and having a clear idea of JVM, JIT or JDK helps in java programming.

12/08/2013

History of Java ::

Java is a general-purpose, concurrent, class-based, object-oriented computer programming language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. Java applications are typically compiled to bytecode (class file) that can run on any Java virtual machine (JVM) regardless of computer architecture. Java is, as of 2012, one of the most popular programming languages in use, particularly for client-server web applications, with a reported 10 million users. Java was originally developed by James Gosling at Sun Microsystems (which has since merged into Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++, but it has fewer low-level facilities than either of them.
The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1991 and first released in 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun relicensed most of its Java technologies under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java and GNU Classpath.

James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. Java was originally designed for interactive television, but it was too advanced for the digital cable television industry at the time. The language was initially called Oak after an oak tree that stood outside Gosling's office; it went by the name Green later, and was later renamed Java, from Java coffee, said to be consumed in large quantities by the language's creators. Gosling aimed to implement a virtual machine and a language that had a familiar C/C++ style of notation.
Sun Microsystems released the first public implementation as Java 1.0 in 1995. It promised "Write Once, Run Anywhere" (WORA), providing no-cost run-times on popular platforms. Fairly secure and featuring configurable security, it allowed network- and file-access restrictions. Major web browsers soon incorporated the ability to run Java applets within web pages, and Java quickly became popular. With the advent of Java 2 (released initially as J2SE 1.2 in December 1998 – 1999), new versions had multiple configurations built for different types of platforms. For example, J2EE targeted enterprise applications and the greatly stripped-down version J2ME for mobile applications (Mobile Java). J2SE designated the Standard Edition. In 2006, for marketing purposes, Sun renamed new J2 versions as Java EE, Java ME, and Java SE, respectively.
In 1997, Sun Microsystems approached the ISO/IEC JTC1 standards body and later the Ecma International to formalize Java, but it soon withdrew from the process. Java remains a de facto standard, controlled through the Java Community Process. At one time, Sun made most of its Java implementations available without charge, despite their proprietary software status. Sun generated revenue from Java through the selling of licenses for specialized products such as the Java Enterprise System. Sun distinguishes between its Software Development Kit (SDK) and Runtime Environment (JRE) (a subset of the SDK); the primary distinction involves the JRE's lack of the compiler, utility programs, and header files.
On November 13, 2006, Sun released much of Java as free and open source software, (FOSS), under the terms of the GNU General Public License (GPL). On May 8, 2007, Sun finished the process, making all of Java's core code available under free software/open-source distribution terms, aside from a small portion of code to which Sun did not hold the copyright.
Sun's vice-president Rich Green said that Sun's ideal role with regards to Java was as an "evangelist." Following Oracle Corporation's acquisition of Sun Microsystems in 2009–2010, Oracle has described itself as the "steward of Java technology with a relentless commitment to fostering a community of participation and transparency". This did not hold Oracle, however, from filing a lawsuit against Google shortly after that for using Java inside the Android SDK (see Google section below). Java software runs on laptops to data centers, game consoles to scientific supercomputers. There are 930 million Java Runtime Environment downloads each year and 3 billion mobile phones run Java. On April 2, 2010, James Gosling resigned from Oracle.