WEB-INF Directory

Today I would like to explore more how the WEB-Content directory is structured, and mainly how the Web.xml file. I will do this using mainly [1], that is the official information from SUN.

The structure of the WEB-INF is not too complicated.

/WEB-INF/

/WEB-INF/web.xml

/WEB-INF/lib/

/WEB-INF/classes/

The /classes directory for servlet and utility classes. The classes in this directory must be available to the application class loader.

The /lib area for Java ARchive files. These files contain servlets, beans, and other utility classes useful to the Web application.

The web.xml file is an xml file ( ahhhh!!) that contains the configuration of the servlet.

<?xml version=”1.0″ encoding=”UTF-8″?>

<web-app id=”WebApp_ID” version=”2.4″ 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”>

<display-name>ZSVNXmlRpcServer

</display-name> <servlet>

<description/>

<display-name>rpc</display-name>

<servlet-name>rpc</servlet-name>

<servlet-class>

com.zagile.scm.servlet.ZSCMXmlRpcServlet

</servlet-class>

<init-param>

<param-name>enabledForExtensions</param-name>

<param-value>true</param-value>

</init-param>

</servlet>

<servlet-mapping>

<servlet-name>rpc</servlet-name>

<url-pattern>/rpc</url-pattern>

</servlet-mapping>

<welcome-file-list>

<welcome-file>view.jsp</welcome-file>

</welcome-file-list>

</web-app>

Above there is an example of an web.xml file:

There is an good site with references to each TAG used on this file [2]. I will put the one that I find more important here, but go to that page if you need more information.

servlet-class –     The fully-qualified class name of the servlet. Use only one of either the <servlet-class> tags or <jsp-file> tags in your servlet body.

init-param –    Contains a name/value pair as an initialization parameter of the servlet. Use a separate set of <init-param> tags for each parameter.

welcome-file –    File name to use as a default welcome file, such as index.html

servlet-mapping –    The servlet-mapping element defines a mapping between a servlet and a URL pattern.

I wrote this post because I was facing problems due to some problems in my web.xml. This was the error that that were happening when I tried to rise the server:

org.apache.catalina.loader.StandardClassLoader@119cca4
com.sun.ws.rest.impl.container.servlet.ServletAdaptor
java.lang.ClassNotFoundException: com.sun.ws.rest.impl.container.servlet.ServletAdaptor
 at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1360)
 at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)
 at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1083)

My web.xml it was like the old one but with this lines more

</servlet>
<servlet>
<servlet-name>ServletAdaptor</servlet-name>
<servlet-class>com.sun.ws.rest.impl.container.servlet.ServletAdaptor</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>ServletAdaptor</servlet-name>
<url-pattern>/resources/*</url-pattern>
</servlet-mapping>

The program was complaining about that the class was not found, what was correct, I didn’t use this classes so I removed it from my web.xml file and voilà it worked. It seems that these lines were added for the Netbeans that my friend used to open the project I am working( I use eclipse). Well probably I am not an expert in web.xml file, but I am able to understand how it works.

If someone could explain why the netbeans added those lines I would appreciate.

[1] – http://cds-esd.sun.com/ESD6/JSCDL/servlet/2.4-fr/servlet-2_4-fr-spec.pdf

[2] – http://edocs.bea.com/wls/docs61/webapp/web_xml.html