web.xml deployment descriptors

The web application deployment descriptor file does what its name says it does: it describes how the web application should be deployed.

Servlet 2.3 deployment descriptor

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Web Application</display-name>
</web-app>

Servlet 2.4 deployment descriptor

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
	      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	      xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
	      http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
	      version="2.4">

  <display-name>Web Application</display-name>
</web-app>

Servlet 2.5 deployment descriptor

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
	      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	      xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
	      http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	      version="2.5">
</web-app>

Servlet 3.0 deployment descriptor

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
	      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	      xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
	      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
	      version="3.0">
</web-app>

Servlet 3.1 deployment descriptor

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
		 http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
</web-app>

Servlet 4.0 deployment descriptor

The version 4.0 is still under development.