Wednesday, March 13, 2013

comment_icon 0 Web.XML Explained


The web.xml Deployment Descriptor file tell about that how application will be deployed in the server or servlet container such as TOMCAT
This file is Required for every application which will be deployed on Tomcat/Apache . The location of Web.XML is always Application-root/WEB-INF/web.xml or WebContent/WEB-INF/web.xml

There is minimum one tag is required in web.xml that is  <web-app> TAG. This  contains following information
 <?xml version="1.0" encoding="ISO-8859-1"?>
<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/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
     version="2.5">
</web-app>

WEB-APP CAN CONTAIN VARIOUS DIFFERENT ELEMNETS. A complete web-app example is given below please click the TAG for more details

<?xml version="1.0" encoding="UTF-8"?>
<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">

        <!-- ========================================================== -->
        <!-- General -->
        <!-- ========================================================== -->

        <!-- Name the application -->
        <display-name>Example App</display-name>
        <description>An example application which is used to play with some of the features of Tomcat</description>

        <!-- This app is cluster-ready -->
        <distributable />

        <!-- Set timeout to 120 minutes -->
        <session-config>
                <session-timeout>120</session-timeout>
        </session-config>


        <!-- ========================================================== -->
        <!-- Custom Tag Libraries -->
        <!-- ========================================================== -->

        <!-- Taglib declarations are no longer required since JSP 2.0, see Removing taglib from web.xml -->
        <!-- The <taglib> did not need to be a child of <jsp-config> in earlier versions but is required as of Tomcat 7 -->
        <!-- Note that you can only have one <jsp-config> element per web.xml -->
        <!--
        <jsp-config>
                <taglib>
                        <taglib-uri>mytags</taglib-uri>
                        <taglib-location>/WEB-INF/jsp/mytaglib.tld</taglib-location>
                </taglib>
        </jsp-config>
        -->


        <!-- ========================================================== -->
        <!-- JSP Configuration -->
        <!-- ========================================================== -->

        <jsp-config>
                <jsp-property-group>
                        <url-pattern>*.jsp</url-pattern>
                        <include-prelude>/WEB-INF/jspf/prelude1.jspf</include-prelude>
                        <include-coda>/WEB-INF/jspf/coda1.jspf</include-coda>
                </jsp-property-group>
        </jsp-config>


        <!-- ========================================================== -->
        <!-- Context Parameters -->
        <!-- ========================================================== -->

        <context-param>
                <description>Enable debugging for the application</description>
                <param-name>debug</param-name>
                <param-value>true</param-value>
        </context-param>
        <context-param>
                <description>The email address of the administrator, used to send error reports.</description>
                <param-name>webmaster</param-name>
                <param-value>address@somedomain.com</param-value>
        </context-param>


        <!-- ========================================================== -->
        <!-- JNDI Environment Variables -->
        <!-- ========================================================== -->

        <env-entry>
                <env-entry-name>webmasterName</env-entry-name>
                <env-entry-value>Ms. W. Master</env-entry-value>
                <env-entry-type>java.lang.String</env-entry-type>
        </env-entry>
        <env-entry>
                <env-entry-name>cms/defaultUserSettings/recordsPerPage</env-entry-name>
                <env-entry-value>30</env-entry-value>
                <env-entry-type>java.lang.Integer</env-entry-type>
        </env-entry>
        <env-entry>
                <env-entry-name>cms/enableXMLExport</env-entry-name>
                <env-entry-value>false</env-entry-value>
                <env-entry-type>java.lang.Boolean</env-entry-type>
        </env-entry>
        <env-entry>
                <env-entry-name>cms/enableEmailNotifications</env-entry-name>
                <env-entry-value>true</env-entry-value>
                <env-entry-type>java.lang.Boolean</env-entry-type>
        </env-entry>


        <!-- ========================================================== -->
        <!-- Servlets -->
        <!-- ========================================================== -->

        <!-- Simple Servlet, provide a name, class, description and map to URL /servlet/SimpleServlet -->
        <servlet>
                <servlet-name>Simple</servlet-name>
                <servlet-class>SimpleServlet</servlet-class>
                <description>This is a simple Hello World servlet</description>
        </servlet>
        <servlet-mapping>
                <servlet-name>Simple</servlet-name>
                <url-pattern>/servlet/SimpleServlet</url-pattern>
        </servlet-mapping>

        <!-- CMS Servlet, responds to *.cms URL's -->
        <servlet>
                <!-- Identification -->
                <servlet-name>cms</servlet-name>
                <servlet-class>com.metawerx.servlets.ContentManagementSystem</servlet-class>
                <description>This servlet handles requests for the CMS (it is a controller in an MVC architecture)</description>

                <!-- This servlet has two parameters -->
                <init-param>
                        <param-name>debug</param-name>
                        <param-value>true</param-value>
                </init-param>
                <init-param>
                        <param-name>detail</param-name>
                        <param-value>2</param-value>
                </init-param>

                <!-- Load this servlet when the application starts (call the init() method of the servlet) -->
                <load-on-startup>5</load-on-startup>
                <!-- <run-at>0:00, 6:00, 12:00, 18:00</run-at> This tag is only valid for Resin -->
        </servlet>

        <!-- Map some URLs to the cms servlet (demonstrates *.extension mapping) -->
        <servlet-mapping>
                <!-- For any URL ending in .cms, the cms servlet will be called -->
                <servlet-name>cms</servlet-name>
                <url-pattern>*.cms</url-pattern>
        </servlet-mapping>

        <!-- Rewriter Servlet, responds to /content/* and /admin/RewriterStatistics URL's -->
        <!-- Define a servlet to respond to /content/* URL's -->
        <servlet>
                <servlet-name>rewriter</servlet-name>
                <servlet-class>com.metawerx.servlets.URLRewriter</servlet-class>
        </servlet>

        <!-- Map some URL's to the rewriter servlet (demonstrates /path/* and specific URL mapping) -->
        <servlet-mapping>
                <!-- For any URL starting with /content/, the rewriter servlet will be called -->
                <servlet-name>rewriter</servlet-name>
                <url-pattern>/content/*</url-pattern>
        </servlet-mapping>
        <servlet-mapping>
                <!-- The rewriter servlet can also be called directly as /admin/RewriterStatistics, to return stats -->
                <servlet-name>rewriter</servlet-name>
                <url-pattern>/admin/RewriterStatistics</url-pattern>
        </servlet-mapping>

        <!-- PathJSP Servlet, maps /shop/item/* URL's to a JSP file -->
        <!-- Define a JSP file to respond to /shop/item/* URL's -->
        <servlet>
                <servlet-name>pathjsp</servlet-name>
                <jsp-file>pathfinder.jsp</jsp-file>
        </servlet>

        <!-- Map some URL's to the pathjsp servlet (demonstrates /long/path/* URL mapping) -->
        <servlet-mapping>
                <!-- For any URL starting with /shop/item/, the pathjsp servlet will be called -->
                <servlet-name>pathjsp</servlet-name>
                <url-pattern>/shop/item/*</url-pattern>
        </servlet-mapping>


        <!-- ========================================================== -->
        <!-- Filters -->
        <!-- ========================================================== -->

        <!-- Example filter to set character encoding on each request (from Tomcat servlets-examples context) -->
        <filter>
                <filter-name>Set Character Encoding</filter-name>
                <filter-class>filters.SetCharacterEncodingFilter</filter-class>
                <init-param>
                        <param-name>encoding</param-name>
                        <param-value>EUC_JP</param-value>
                </init-param>
        </filter>
        <filter-mapping>
                <filter-name>Set Character Encoding</filter-name>
                <url-pattern>/*</url-pattern>
        </filter-mapping>

        <!-- Example filter to dump the HTTP request at the top of each page (from Tomcat servlets-examples context) -->
        <filter>
                <filter-name>Request Dumper Filter</filter-name>
                <filter-class>filters.RequestDumperFilter</filter-class>
        </filter>
        <filter-mapping>
                <filter-name>Request Dumper Filter</filter-name>
                <url-pattern>/*</url-pattern>
        </filter-mapping>


        <!-- ========================================================== -->
        <!-- Listeners -->
        <!-- ========================================================== -->

        <!-- Define example application events listeners -->
        <listener>
                <listener-class>com.metawerx.listener.ContextListener</listener-class>
        </listener>
        <listener>
                <listener-class>com.metawerx.listener.SessionListener</listener-class>
        </listener>


        <!-- ========================================================== -->
        <!-- Security -->
        <!-- ========================================================== -->

        <!-- Define roles -->
        <security-role>
                <role-name>admin</role-name>
        </security-role>
        <security-role>
                <role-name>cms_editors</role-name>
        </security-role>
        
        <!-- Define a constraint to restrict access to /private/* -->
        <security-constraint>

                <display-name>Security constraint for the /private folder</display-name>

                <web-resource-collection>
                        
                        <web-resource-name>Protected Area</web-resource-name>
                        <url-pattern>/private/*</url-pattern>
                        
                        <!-- If you list http methods, only those methods are protected. -->
                        <!-- Leave this commented out to protect all access -->
                        <!--
                        <http-method>DELETE</http-method>
                        <http-method>GET</http-method>
                        <http-method>POST</http-method>
                        <http-method>PUT</http-method>
                        -->

                </web-resource-collection>

                <auth-constraint>
                        <!-- Only only administrator and CMS editors to access this area -->
                        <role-name>admin</role-name>
                        <role-name>cms_editors</role-name>
                </auth-constraint>

        </security-constraint>

        <!-- FORM based authentication -->
        <!-- Leave this commented out, we will use BASIC (HTTP) authentication instead -->
        <!--
        <login-config>
                <auth-method>FORM</auth-method>
                <form-login-config>
                        <form-login-page>/login.jsp</form-login-page>
                        <form-error-page>/error.jsp</form-error-page>
                </form-login-config>
        </login-config>
        -->
        <!-- This application uses BASIC authentication -->
        <login-config>
                <auth-method>BASIC</auth-method>
                <realm-name>Editor Login</realm-name>
        </login-config>

        <!-- Define a constraint to force SSL on all pages in the application -->
        <security-constraint>

                <web-resource-collection>
                        <web-resource-name>Entire Application</web-resource-name>
                        <url-pattern>/*</url-pattern>
                </web-resource-collection>

                <user-data-constraint>
                        <transport-guarantee>CONFIDENTIAL</transport-guarantee>
                </user-data-constraint>

        </security-constraint>


        <!-- ========================================================== -->
        <!-- Error Handler -->
        <!-- ========================================================== -->

        <!-- Define an error handler for 404 pages -->
        <error-page>
                <error-code>404</error-code>
                <location>/error404.jsp</location>
        </error-page>

        <!-- Define an error handler for java.lang.Throwable -->
        <error-page>
                <exception-type>java.lang.Throwable</exception-type>
                <location>/errorThrowable.jsp</location>
        </error-page>


        <!-- ========================================================== -->
        <!-- Extra MIME types -->
        <!-- ========================================================== -->

        <!-- Set XML mime-mapping so spreadsheets open properly instead of being sent as an octet/stream -->
        <mime-mapping>
                <extension>xls</extension>
                <mime-type>application/vnd.ms-excel</mime-type>
        </mime-mapping>


        <!-- ========================================================== -->
        <!-- Locale -->
        <!-- ========================================================== -->

        <!-- Set Locale Encoding -->
        <locale-encoding-mapping-list>
                <locale-encoding-mapping>
                        <locale>ja</locale>
                        <encoding>Shift_JIS</encoding>
                </locale-encoding-mapping>
        </locale-encoding-mapping-list>


        <!-- ========================================================== -->
        <!-- Welcome Files -->
        <!-- ========================================================== -->

        <!-- Define, in order of preference, which file to show when no filename is defined in the path -->
        <!-- eg: when user goes to http://yoursite.com/ or http://yoursite.com/somefolder -->
        <!-- Defaults are provided in the server-wide web.xml file, such as index.jsp, index.htm -->
        <!-- Note: using this tag overrides the defaults, so don't forget to add them here -->
        <welcome-file-list>
                <!-- Use index.swf if present, or splash.jsp, otherwise just look for the normal defaults -->
                <welcome-file>index.swf</welcome-file>
                <welcome-file>splash.jsp</welcome-file>
                <welcome-file>index.html</welcome-file>
                <welcome-file>index.htm</welcome-file>
                <welcome-file>index.jsp</welcome-file>
        </welcome-file-list>

</web-app>