SERVLETS

Introduction

The Java web server is JavaSoft's own web Server. The Java web server is just a part of a larger framework, intended to provide you not just with a web server, but also with tools. To build customized network servers for any Internet or Intranet client/server system. Servlets are to a web server, how applets are to the browser.

About Servlets

Servlets provide a Java-based solution used to address the problems currently associated with doing server-side programming, including inextensible scripting solutions, platform-specific APIs, and incomplete interfaces.

Servlets are objects that conform to a specific interface that can be plugged into a Java-based server. Servlets are to the server-side what applets are to the client-side - object byte codes that can be dynamically loaded off the net. They differ from applets in that they are faceless objects (without graphics or a GUI component). They serve as platform independent, dynamically loadable, pluggable helper byte code objects on the server side that can be used to dynamically extend server-side functionality.

For example, an HTTP Servlets can be used to generate dynamic HTML content. When you use Servlets to do dynamic content you get the following advantages:

Ø   They’re faster and cleaner than CGI scripts

Ø   They use a standard API (the Servlets API)

Ø   They provide all the advantages of Java (run on a variety of servers without needing to be rewritten).

Attractiveness of Servlets

There are many features of Servlets that make them easy and attractive to use. These include:

Ø   Easily configured using the GUI-based Admin tool

Ø   Can be loaded and invoked from a local disk or remotely across the network.

Ø   Can be linked together, or chained, so that one Servlets can call another Servlets, or several Servlets in sequence.

Ø   Can be called dynamically from within HTML pages, using server-side include tags.

Ø   Are secure - even when downloading across the network, the Servlets security model and Servlets sandbox protect your system from unfriendly behavior.

Advantages of the Servlet API

One of the great advantages of the Servlet API is protocol independence. It assumes nothing about:

·         The protocol being used to transmit on the net

·         How it is loaded

·         The server environment it will be running in

These qualities are important, because it allows the Servlet API to be embedded in many different kinds of servers. There are other advantages to the Servlet API as well. These include:

·         It’s extensible - you can inherit all your functionality from the base classes made available to you.

·         It’s simple, small, and easy to use.