A Brief History Of Java Programming Language Introduction It is been seen that current programming problems are complex. Structured programming cannot manage complexity of complex programs. Obeject Oriented Programming makes it possible to organise large and complex programs using classes, objects, inheritance, polymorphism and encapsulation. C++ for years was most widely used OOP language. Due to advent of internet, Java became widely used and gained tremendous popularity. Java came as the programming language which was widely used in the consumer electronic devices such as microwaves, television etc. A lot of research was been done to build a small, reliable, processor independent, real-time, safe and distributed software for these systems. With the coming of Internet and WWW, Java went on becoming a full fledged programming language, shifting its focus from consumer devices to a vast platform to create powerful, distributed, robust and secure applications. A Brief History Of Java Java Programming Language was conceived by the effort of 5 great people, James Gosling, Patrick Naughton, Chris Warth, Mike Sheridan and Ed Frank. They all worked for Sun Microsystems, Inc and came up with Java in 1991. The language took 18 months to develop and had a initial name as "Oak" which was renamed to Java in 1995, due to copyright issues. The idea was to develop a language which was platform-independent and which could create embedded softwares for consumer electronic devices. C and C++ were quite inefficient for the purpose because they were not platform-independent as there programs have to be compiled for particular hardware before execution. Also, the compiled code was inefficient for other processors and it had to be recompiled. So the team of 5 also called as Green Team began to work in developing a easier and costefficient solution. They worked for 18 months in developing a portable, platform-independent language that could create a code which can run on variety of processors under differing environments. The above necessity led to creation of Java. At the same time, Internet and WWW were becoming popular day-by-day. The web programs lacked the features of platform-independence. It required programs that could run on any operating system irrespective of hardware and software configuration. It required small and portable programs that could be securely transported over the network. The programming language available to suit such requirements was Java. Many developers soon realized that architectural neutral language like Java would be best for writing programs for internet. Thus forcus of Java was shifted from consumer electronics to World Wide Web. Today, Java is not an ordinary programming language. It is a technology which is simple, Object Oriented, Distributed, Robust, Secure, Architecture neutral, Portable, Interpreated, Multithreaded, High Performance and Dynamic.
Java Application Types This section reviews different types of Java applications before moving on to Servlets. Java can be used to develop different types of applications: • • •
Java Console Applications Java GUI Applications Java Applets Standalone Applications Web Applications Distributed Applications
Standalone Applications A standalone application is a program that runs on your computer. It is more or less like a C or C++ program.
Applets An applet is an application designed to travel over the Internet and to be executed on the client machine by a Java-Compatible web browser like Internet Explorer or Netscape. Applets are also Java programs but they reside on the servers. An applet can not be executed like standalone application. Applet can be executed only by embedding it into an HTML page like an image or sound file. To run an applet you need to access an HTML page which has applet embedded into it. When the web browser downloads such an HTML page, it subsequently loads the executable file, which contains Applet and then executes it on the local machine. Web Applications Web applications run on the Web Server. Web applications are accessed through web clients i.e. web browsers like Internet Explorer or Netscape. Whenever you access some web site by specifying the URL (Universal Resource Locator), you are accessing some web application. The main components of a web application written in Java are: Java Servlets Java Server Pages (JSP), and HTML Java Servlets are also Java programs, which run on the Server and then send the result/response to the client. JSP pages can be thought of as a combination of HTML and Java Code. The Web Server converts JSP pages into Java Servlets before execution.
You access the web application by specifying the URL. If the URL corresponds to an HTML page the web server simply returns the HTML page to the client, which then displays it. If the URL corresponds to the Servlet or JSP then it is executed on the Server and the result/response is returned to the client, which is then displayed by the client. Distributed Applications Java application can be divided into a number of modules/components (Java programs), which can run on different machines. The Java programs/applications running on different machines can communicate with each other. To be more precise the Java Objects on one machine can invoke methods on the Java Objects running on another machine. Thus Java has the support for the distributed processing in the language itself.
Benefits of JAVA The Java programming language is an object-oriented programming language created by Sun Microsystems.
JAVA is object oriented because Java programming is centered on creating objects, manipulating objects, and making objects work together. An object can be perceived as a real life object or business object. Example: real life object like chair, table, person while business objects like bank account, mortgage, invoice etc. Object-oriented programming provides greater flexibility, modularity and reusability.
Benefits of using JAVA programming Security Features: Both the language and the platform were designed from the ground up with security in mind. Portability: One of the most compelling reasons to move to Java is its platform independence. Distributed: Java is designed to make distributed computing easy with the networking capability that is inherently integrated into it. Multi Threaded: Multithreaded is the capability for a program to perform several tasks simultaneously within a program. Reliable and Robust: Java puts a lot of emphasis on early checking for possible errors, as Java compilers are able to detect many problems that would first show up during execution time in other languages.
Dynamic and Extensible: Java code is organized in modular object-oriented units called classes. Classes are stored in separate files and are loaded into the Java interpreter only when needed. This means that an application can decide as it is running what classes it needs and can load them when it needs them. It also means that a program can dynamically extend itself by loading the classes it needs to expand its functionality. Network Centric Programming: Java makes it unbelievably easy to work with resources across a network and to create network-based applications using client/server or multitier architectures. Internationalization: Java is the only commonly used programming language that has internationalization features at its very core
