web services returning list error

[Mumuney Abdlquadri]

Hi All,

I have a web service, which is basically a stateless session bean that
extends an abstract class(but itself is not abstract) and uses
entitymanager class to query database. It then returns the result as
List<T>.

When I try to test the webservice I get this:


java.lang.NullPointerException at java.io.File.(File.java:222) at
org.glassfish.webservices.monitoring.WebServiceTesterServlet.initializePort(WebServiceTesterServlet.java:505)
at org.glassfish.webservices.monitoring.WebServiceTesterServlet.doGet(WebServiceTesterServlet.java:165)
at org.glassfish.webservices.monitoring.WebServiceTesterServlet.invoke(WebServiceTesterServlet.java:100)
at org.glassfish.webservices.EjbWebServiceServlet.service(EjbWebServiceServlet.java:110)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at
com.sun.grizzly.http.servlet.FilterChainImpl.doFilter(FilterChainImpl.java:195)
at com.sun.grizzly.http.servlet.FilterChainImpl.invokeFilterChain(FilterChainImpl.java:139)
at com.sun.grizzly.http.servlet.ServletAdapter.doService(ServletAdapter.java:376)
at com.sun.grizzly.http.servlet.ServletAdapter.service(ServletAdapter.java:329)
at com.sun.grizzly.tcp.http11.GrizzlyAdapter.service(GrizzlyAdapter.java:166)
at com.sun.enterprise.v3.server.HK2Dispatcher.dispath(HK2Dispatcher.java:100)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:245)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:8
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57)
at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at
com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309)
at java.lang.Thread.run(Thread.java:619)

Any ideas please.

Regards