求助:关于Hessian实现webservice的问题

今天在弄那个Hessian,想用它实现web服务,于是按官方网站的document的例子做了一个简单的hello程序,报了一堆错误,刚接触这个,实在不知道原因何在.
请教一下们,在此先谢了!!
程序完整代码:
1,对外暴露的业务接口

package com.neoman.hession;

public interface BasicAPI {
	public String hello();
}

2,服务器端实现

package com.neoman.hession;

import com.caucho.hessian.server.HessianServlet;

public class BasicService extends HessianServlet implements BasicAPI {
	private String str="Hello World";
	public void setStr(String str) {
		this.str = str;
	}
	public String hello() {
		// TODO Auto-generated method stub
		return str;
	}

}

3,客户端测试代码

package com.neoman.hession;

import java.net.MalformedURLException;

import com.caucho.hessian.client.HessianProxyFactory;

public class Test {

	/**
	 * @param args
	 * @throws Exception 
	 */
	public static void main(String[] args) throws Exception {
		// TODO Auto-generated method stub
		String url = "http://localhost:8080/HessionTest/hello";

		HessianProxyFactory factory = new HessianProxyFactory();
		BasicAPI basic=(BasicAPI) factory.create(BasicAPI.class, url);	

		System.out.println("hello(): " + basic.hello());
	}

}

4, web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app 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">
	<servlet>
   <servlet-name>hello</servlet-name>
   <servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
    <init-param>
      <param-name>home-class</param-name>
      <param-value>com.neoman.hession.BasicService</param-value>
    </init-param>
    <init-param>
      <param-name>home-api</param-name>
      <param-value>com.neoman.hession.BasicAPI</param-value>
    </init-param>
  </servlet>

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

</web-app>

报的错误:Exception in thread "main" com.caucho.hessian.client.HessianRuntimeException: com.caucho.hessian.io.HessianProtocolException: 500: java.io.IOException: Server returned HTTP response code: 500 for URL: http://localhost:8080/HessionTest/hello
at com.caucho.hessian.client.HessianProxy.invoke(HessianProxy.java:183)
at $Proxy0.hello(Unknown Source)
at com.neoman.hession.Test.main(Test.java:21)
Caused by: com.caucho.hessian.io.HessianProtocolException: 500: java.io.IOException: Server returned HTTP response code: 500 for URL: http://localhost:8080/HessionTest/hello
at com.caucho.hessian.client.HessianProxy.invoke(HessianProxy.java:167)
... 2 more
Caused by: java.io.IOException: Server returned HTTP response code: 500 for URL: http://localhost:8080/HessionTest/hello
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:494)
at sun.net.www.protocol.http.HttpURLConnection$6.run(HttpURLConnection.java:1227)
at java.security.AccessController.doPrivileged(Native Method)
at sun.net.www.protocol.http.HttpURLConnection.getChainedException(HttpURLConnection.java:1221)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:910)
at com.caucho.hessian.client.HessianProxy.invoke(HessianProxy.java:149)
... 2 more
Caused by: java.io.IOException: Server returned HTTP response code: 500 for URL: http://localhost:8080/HessionTest/hello
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1174)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:367)
at com.caucho.hessian.client.HessianProxy.invoke(HessianProxy.java:140)
... 2 more

http://localhost:8080/HessionTest/hello

# <servlet-mapping> 
#     <servlet-name>hello</servlet-name> 
#     <url-pattern>/hello</url-pattern> 
#   </servlet-mapping>

mapping is wrong ... look again...

我的工程名字是HessianTest
那映射写成:<url-pattern>/HessianTest/hello</url-pattern>
么???
能否直接点,谢谢啦

老田...看来又是JNDI问题,那么象EJB的....

web.xml改成:

<?xml version="1.0" encoding="UTF-8"?>  
<web-app 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">  
    <servlet>  
   <servlet-name>hello</servlet-name>  
   <servlet-class>com.neoman.hession.BasicService </servlet-class>    
  </servlet>  
  
  <servlet-mapping>  
    <servlet-name>hello</servlet-name>  
    <url-pattern>/hello</url-pattern>  
  </servlet-mapping>  
</web-app>