JAVA AND THE INTERNET in Java

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In discussing the evolution of Java, we need to clarify the terms Java and Java platform and the JDK, now called the SDK. Java and the SDK have become synonymous. However, in reality Java the language should be viewed as a separate entity from Sun s reference implementation of the language and developer s kit that have traditionally shared the same version number. Java or, as Sun likes to refer to it, the Java platform, is the abstract language and specification that surrounds the language. The SDK is Sun s product and an implementation of the specification that is used by software engineers to create applications. If you prefer, the Java platform is conceptual and the SDK is physical. You might have noticed from the last paragraph that the SDK is an implementation, not necessarily the implementation. In theory, if not practice, many other organizations could provide their own implementation of the Java platform. In fact some organizations such as IBM and Hewlett-Packard provide their own compilers and virtual machines. For more information on the differences between Java and the SDK, see Sun s web site at java.sun.com/products/jdk/1.2/java2.html. For the purposes of this book, any reference to Java and a version number refers to both the Java specification and Sun s SDK unless explicitly stated.

On May 23, 1995, Sun officially released Java. The first public release of the Java Development Kit (JDK) was version 1.02. Amazingly, Java s core architecture and programming language have not changed substantially. However, Sun has released two additional major releases and several minor releases of Java and the corresponding JDK since its first public release.

January 23, 1996 Sun ships Java 1.0 JDK October 30, 1994 Java s public introduction April 1993 Mosaic 1.0 release Summer 1992 Green Project introduces *7 December 1990 Green Project Formation May 1996 First JavaOne conference February 1997 Sun ships JDK 1.1 December 9, 1998 Sun ships Java 2, SDK 1.2

Figure C.1 As this timeline depicts, Java was developed in the early 1990s, publicly introduced in the mid 1990s, and has been reintroduced, through J2ME, to consumer electronic and embedded devices in the late 1990s.

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Java 1.02 As the first public release, Java 1.02 attempted to offer a best-of-breed programming language, borrowing ideas and trying to avoid the mistakes of its predecessor languages. Java was intended to look a lot like C++ while also providing many of the key features available in programming languages such as Smalltalk, Eiffel, and other object-oriented languages. Java 1.02 introduced a new object-oriented programming language that provided a platform-neutral development environment that produced applications that were considered more secure and reliable than applications produced with other programming languages. As previously mentioned, its platform independence was able to shine through in new groundbreaking features, such as the Java applet, that were important to the development of the early Internet. Yet, like all first releases, Java 1.02 had some notable shortcomings as well. Java 1.1 In many cases, a second release of something in the software industry implies fixing that which was discovered broken, or not quite right, by the users in the first release. Java 1.1, including all the subsequent 1.1.x (Sun released 8 minor releases from 1.1.1 to 1.1.8) minor releases, did fix many shortcomings, but it also introduced many new features. In fact, the version number associated with Java s second major release is a real misnomer. The 1.1 version of Java included many substantial additions. Along with performance enhancements and API enhancements in the event model, networking, and input/output (IO) support, the 1.1.x releases were monumental in the new APIs they introduced. These include server-side programming, Java database connectivity (JDBC), a new component model (JavaBeans), Reflection, and Java Native Interface to name a few. Java 2 With the introduction of Java 2, Sun made a stronger distinction between the Java platform and the JDK. In fact, they even changed the name of the Java Development Kit to the Software Development Kit (SDK). The Java language and specification jumped version numbers from Java 1.1 to Java 2. The development kit and runtime were renamed but kept the original version number progression. So what was the JDK became the Java 2 SDK, Standard Edition version 1.2 or just plain SDK 1.2 for short. Along with the name and packaging realignment, the new SDK 1.2 offered many enhancements to the existing API, along with a few important new features such as a new set of collection classes and a new set of GUI components (the GUI components were actually introduced as an add-on package in late Java 1.1.x releases but made a permanent part of the SDK 1.2). Of course, Java 2 also brought a split in the editions of Java.

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