Demystifying Java Internals (An introduction)

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Volume 1
Java is a technology that makes it easy to develop distributed applications, which are programs that can be executed by multiple computers across a network, whether it is local or a wide area network. Java has expanded the Internet role from an arena for communications to a network on which full-fledged applications can be executed. Ultimately, this open source technology gives the impression of network programming across diverse platform.
This article illustrates these underlying contents in detail:

• Genesis of Java
  
• Java and the World Wide Web
  
• Beauty of Java: The “Bytecode”
  
• Java Framework Configuration
  
• Java Features
  
• Summary
  

Before Java, the Internet was used primarily for sharing information, though developers soon realized that the World Wide Web could meet some business needs. The WWW is a technology that treats Internet resources as linked and it has revolutionized the way people access information. The web has enabled Internet users to access Internet services without learning sophisticated cryptic commands. Through the web, corporations can easily provide product information and even sell merchandise. Java technology takes this a step further by making it possible to offer fully interactive applications via the web.

In particular, Java programs can be embedded into web documents, turning static pages into applications that run on the user’s computer. Java has the potential to change the function of the Internet, much as the web has changed the way people access the Internet. In other words, not only will the network provide information, it will also serve as an operating system.

Genesis of Java

In 1990, Java was conceived by James Gosling, Patrick Naughton, and Ed Frank at Sun Microsystems. This language was initially known as Oak. Oak preserved the familiar syntax of C++ but omitted the potentially dangerous features, such as pointer arithmetic, operator overloading, and explicit resource references. Oak incorporated memory management directly into the language, freeing the programmer to concentrate on the task to be performed by the program. As Oak matured, the WWW was growing dramatically, and the component team at Sun realized that Oak was perfectly suited to Internet programming. Thus, in 1994, they completed work on a product known as WebRunner, an early browser written in Oak. WebRunner was later renamed HotJava, and it demonstrate the power of Oak as Internet development tool. Finally, in 1995, Oak was renamed Java and introduced at Sun. Since then, Java’s rise in popularity has been dramatic.

Java is related to C++, which is a direct descendent of C. Much of the character of Java is inherited from those two languages. From C, Java derives its semantics. Java is truly an object-oriented, case-sensitive programming language. Many of Java OOPs features were influenced by C++. The original Impetus for Java was not the Internet. Instead, the primary motivation was the need for a platform-independent language that could be used to create software to be embedded in various consumer electronic devices. The trouble with C and C++ is that they are designed to be compiled for a specific target, so an easier and more cost-efficient solution was Java technology, a truly open source technology.

Java and the World Wide Web

Today, the web acts as a convenient transport mechanism for Java programs, and the Web’s ubiquity has popularized Java as an Internet development tool. Java expands the universe of objects that can move about freely in cyberspace. In a network, two very broad categories of objects are transmitted between a server and your personal computer: passive information and dynamic active programs. For example, when you read your e-mails, you are viewing passive data. However, a second type of object can be transmitted to your computer: a dynamic, self-executing program. For example, a program might be provided by the server to display properly the data that the server is sending. A dynamic network program presents serious problems in the areas of security and portability. As you will see, Java addresses those concerns effectively by introducing a new form of program: the applet.

Java primarily stipulates two types of programs: applets and application. An applet is an application designed to be transmitted over the Internet and executed by a Java-compatible web browser. An applet is a tiny Java program that can be dynamically downloaded across the network. It is a kind of program that can react to user input and be changed dynamically. On the other hand, an application runs on your computer under the operating system of that computer, such as an application created in the C or C++ language.

Java technology provides portable code execution across diverse platforms. Many types of computers and operating systems are in use throughout the world, and many are connected to the Internet. For programs to be dynamically downloaded to all the various type of platforms connected to the Internet, some means of generating portable executing code is needed.

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