<?xml version="1.0" encoding="ISO-8859-1"?>
<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">
    
    <resource-ref>
        <res-ref-name>jdbc/DataSource</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
        <res-sharing-scope>Shareable</res-sharing-scope>
    </resource-ref>
    
    <welcome-file-list>
        <welcome-file>jsp/EMPdemo.jsp</welcome-file>
    </welcome-file-list>
</web-app>

The default namespace of the above XML document is http://java.sun.com/xml/ns/javaeeImage Removed. The XML elements that do not have a namespace prefix belong to the default namespace.

With Servlet 2.5 specification, many of the declarations done through web.xml can also be done through corresponding annotations in the servlets and JSPs. When both annotations and web.xml are provided, the declarations in web.xml takes precedence over annotations.

<web-app xmlns="http://geronimo.apache.org/xml/ns/j2ee/web-2.0.1"
          xmlns:naming="http://geronimo.apache.org/xml/ns/naming-1.2"
          xmlns:sec="http://geronimo.apache.org/xml/ns/security-2.0"
          xmlns:sys="http://geronimo.apache.org/xml/ns/deployment-1.2">

    <sys:environment>
        <sys:moduleId>
            <sys:groupId>samples</sys:groupId>
            <sys:artifactId>EmployeeDemo</sys:artifactId>
            <sys:version>2.5</sys:version>
            <sys:type>war</sys:type>
        </sys:moduleId>
        
        <sys:dependencies>
            <sys:dependency>
                <sys:groupId>samples</sys:groupId>
                <sys:artifactId>EmployeeDatasource</sys:artifactId>
                <sys:version>2.5</sys:version>
                <sys:type>rar</sys:type>
            </sys:dependency>
        </sys:dependencies>
    </sys:environment>
    
    <context-root>/EmployeeDemo</context-root>
        <naming:resource-ref>
        <naming:ref-name>jdbc/DataSource</naming:ref-name>
        <naming:resource-link>jdbc/EmployeeDatasource</naming:resource-link>
    </naming:resource-ref>
</web-app>

The default namespace of the above XML document is http://geronimo.apache.org/xml/ns/j2ee/web-2.0.1Image Removed. The XML elements that do not have a namespace prefix belong to the default namespace.

....
....
Context initContext = new InitialContext();
Context envContext  = (Context)initContext.lookup("java:comp/env");
DataSource ds = (DataSource)envContext.lookup("jdbc/DataSource");
Connection con = ds.getConnection();
....
....