The following sections describe the deployment descriptor elements defined in the web.xml file under the root element <web-app>:
context-param
description
display-name
distributable
ejb-ref
ejb-local-ref
env-entry
error-page
filter
filter-mapping
icon
listener
login-config
mime-mapping
resource-env-ref
resource-ref
security-constraint
security-role
servlet
servlet-mapping
session-config
taglib
welcome-file-list
All J2EE web applications are configured with a web.xml deployment descriptor. It’s a very important file, and it’s good to know something about it.
<?xml version=”1.0″ encoding=”UTF-8″?>
<!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>Hello, World!</display-name>
<description>Welcome to JavaServer Faces</description>
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Development</param-value>
</context-param>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>30 </session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>faces/index.xhtml</welcome-file>
</welcome-file-list>
</web-app>
<display-name></display-name> – short name displayed by GUI tools
<description></description> – descriptive name about our Web application
<servlet></servlet> – our servlet definition
<servlet-name>Faces Servlet</our-servlet-name> – the name of our servlet
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class> – the class our servlet belongs to
<load-on-startup>1</load-on-startup> – load order on startup (0, 1, 2, etc); lower numbers first, then higher ones; when the value is < 0 or no value, then our servlet is loaded when the web container chooses
<servlet-mapping></our-servlet-mapping> our servlet mapping on URL name
<servlet-name>Faces Servlet</our-servlet-name> the name of our servlet (must be the same in both cases: <servlet></servlet> and <servlet-mapping></servlet-mapping>)
<url-pattern>/faces/*</url-pattern> the name of our servlet mapped to an URL pattern (we use that to get to the servlet in a web browser that is /faces/our-servlet-name)
<session-config></session-config> – session configuration
<session-timeout>30 </session-timeout>– how long your session lasts
<welcome-file-list></welcome-file-list> – welcome files show when no filename is provided in the URL
<welcome-file>faces/index.xhtml</welcome-file> – your welcome file is index.xhtml
Tomasz Zackiewicz 