JavaServer Pages™ (JSP™) is a programming technology for websites that allows the seamless integration of Java™ programs into the normal functioning of a website and within active HyperText Markup Language (HTML) documents. The technology can be used to display dynamic data or to process user input. It also has the advantage of being able to access information on the server on which it is running and being portable to any system or web server with the correct suite of programs installed.
One of the largest differences when developing interactive or dynamic websites with JavaServer Pages™ is that the pages are able to be used readily on any web server that has a program running and capable of interpreting them. The portability of these types of programs is made possible by programs such as Apache Tomcat™ that are able to function across several platforms and web servers to enable JavaServer Pages™. These programs can be run in the background or on top of other web servers to provide the functionality needed. The actual pages are often human readable and look like regular HTML pages with Java™ embedded in the code.
There are many differences between JavaServer Pages™ and more traditional web-based languages. One of these is that there are few security restrictions on communications between the web server and the pages because they are integrated. This is in stark contrast to other common gateway interface (CGI) languages, which are run independently of the web server and have heavy restrictions on the actions they can perform.
A very convenient difference for programmers is that Java™ code can be directly placed into an HTML page and executed from within the page as if it were part of another block of code located elsewhere. With Java Server Pages™, an HTML page can be loaded and the dynamically generated portions simply inserted as needed. This is different from many CGI languages in which the source code that is executed must generate the entire HTML page from within the program. This process can be complemented by allowing the server to compile the Java™ code on the fly instead of pre-compiling it, making changes and maintenance to the website much easier.
JavaServer Pages™ offer a more powerful interface for programming than some other similar languages. Some scripting languages are used because they are conveniently available or because they are specifically designed to perform a subset of network functions. A web developer using JavaServer Pages™ has access to nearly the entire Java™ language when creating a website, allowing advanced functions and the ability to use and load new libraries as needed. This is a powerful feature that can make it more efficient to access databases, use new protocols and communicate with remote servers.