Platform Independent Client-Side Applications with Java

That very umph comes with Java. Java was originally developed at Sun Microsystems in 1991 to provide a platform-independent programming language and operating system for consumer electronics (TV sets, toasters and VCRs).

In syntax and execution, Java is a lot like a simplified version of C++. ("simplified" should be read in the previous sentence as "an improved"). It is a highly robust, distributed, high performance, object-oriented, multi-threaded language with all of the usual features. As such, it builds upon years of C++ development, taking the good and dispensing with the bad.

As it so happened however, Java did not make it into the consumer electronics market. Instead it wound up in our web browsers.

Java seemed to be a perfect fit for the web. The language itself was extremely small (as it was built to go inside toasters and alarm clocks with tiny amounts of memory). Thus it could quickly be transferred over the web.

Further, Java was platform independent. That is, any computer with a Java virtual machine can run a Java program. Programs can be written anywhere and be run anywhere. This is crucial because, as we saw in the case of the client-side scripting languages, if a language can not run on any machine, it cannot be used on the web that must service every machine, language, and environment imaginable.

Platform independence works because Java is an interpreted rather than a compiled language. Unlike C or C++ code, when Java is compiled, it is not compiled into platform specific machine code, but into platform independent byte code. This byte code is distributed over the web and interpreted by a virtual machine (typically built right into a web browser these days) on whichever platform it is being run. Perhaps a picture would be useful...

Thus, as a programmer, you need only concern yourself with the generic Java programming language and compile your applications into bytecode on whatever system you are using. You can then be assured that your bytecode will be executed correctly whether your clients are using Macs, Pcs, Unix boxes or anything else.

Java, of course, demands books worth of explanation and description. So, of course, we will not delve too deeply into the language here. Instead, I recommend that you browse through the resources collected at Gamelan which is the be all and end all of Java resource sites. There you can sample several Java programs yourself and see how amazing Java really is.

Did I say amazing? Well, Java is certainly a great addition to every web developers tool box, but as you might have expected, Java has as many drawbacks as any of the other tools we've discussed already.