Java EE (Java Enterprise Edition) General Discussion

Hello,
I created a new web application in Apache tomcat. I put a HelloWorldExample servlet in Web-inf/classes folder. Then i put an entry into the web.xml file. When i invoke the servlet i get "Servlet Currently Unavailable No.503 "

web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>

<!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>First Examples</display-name>
<description>
My Example servlets and JSP pages.
</description>



<!-- Define servlets that are included in the example application -->

<servlet>
<servlet-name>firstServlet</servlet-name>
<servlet-class>firstServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>HelloWorldExample</servlet-name>
<servlet-class>HelloWorldExample</servlet-class>
</servlet>

<servlet>
<servlet-name>
servletToJsp
</servlet-name>
<servlet-class>
servletToJsp
</servlet-class>
</servlet>
<servlet>
<servlet-name>
CompressionFilterTestServlet
</servlet-name>
<servlet-class>
compressionFilters.CompressionFilterTestServlet
</servlet-class>

</servlet>


<servlet-mapping>
<servlet-name>invoker</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<servlet-mapping>
<servlet-name>
CompressionFilterTestServlet
</servlet-name>
<url-pattern>
/CompressionTest
</url-pattern>
</servlet-mapping>


<servlet-mapping>
<servlet-name>
servletToJsp
</servlet-name>
<url-pattern>
/servletToJsp
</url-pattern>
</servlet-mapping>

<servlet-mapping>
<servlet-name>firstServlet</servlet-name>
<url-pattern>/firstServlet</url-pattern>
</servlet-mapping>

<servlet-mapping>
<servlet-name>HelloWorldExample</servlet-name>
<url-pattern>/HelloWorldExample</url-pattern>
</servlet-mapping>


</web-app>
Hoping for ur replies
Mani.