JAVA

This small article is aimed at web designers who are (mostly) non-programmers and who wish to use 3rd party applets rather than create their own. It sets out to define java from the non-specialist's perspective and guard against a few common misconceptions. Java is a programming language just like any other (e.g. Basic, C, C++), with the following distinctive characteristic: it was developed for networks - especially for the internet and other large networks where different kinds of computer are connected together. To make it better at using networks than other languages, it is (i) compatible with different operating systems, and (ii) can be condensed into extremely small packages for quick network transfer. Java can be divided into: applets, serve’s, beans and applications. Applets are perhaps the most familiar face of java. Applets are tiny programmes that can be embedded into a web page to produce startling effects and interactivity. They don't run on the web server - they are downloaded to the visitor's own computer and run using the site visitor's CPU and memory (known as the "client"). In theory a programme running on the client in this fashion could be a security hazard (it could remove, copy or write files, for example), so applets are strictly controlled by a security manager which prevents them doing a lot of things most programmes can do. For example, applets aren't allowed any kind of access to the client's file system, nor can they send any information elsewhere unless they are explicitly allowed to do so. Servlets are a bit like applets except that they run on the server, not the client. In practice this means they are suitable for quite different kinds of operation, and you don't see them on web pages. Beans are not complete programmes at all. They are an outgrowth of the idea that java should be extremely portable and versatile. Beans contain just single elements of a programme, and can be incorporated by different people into different java programmes. This saves time on development, and allows good ideas to spread quickly and conveniently. Applications are more like "normal" computer programmes. They are usually bigger, and can only run on one computer. They have nothing to do with web pages and HTML. Theoretically your word-processor, web browser and favourite games could all be programmed in java. The advantage if you did this would be that the same files would run on Windows, Mac, Linux, etc. With other languages, you need different versions for the different operating systems.