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How to retrieve collection from EJB to frontend in WSAD?

 
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Posts: 34
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Hi there,
I have a problem in calling a method in EJB from JSP, I am using WSAD5.1.1, below is my source:
Backend
public class CarrierDS{
..
public ArrayList findAllCarrier(){
Connection conn=null;
ArrayList rtnCol = null;
PreparedStatement stat = null;
CarrierPCls getPCls = null;
StringBuffer szSql = new StringBuffer();
ResultSet rs = null;
try{
conn=getConnection();
szSql.append("select carrier_cd, name from car_carrier where carrier_cd like 'AT%' order by carrier_cd");
stat = conn.prepareStatement(szSql.toString());
rs = stat.executeQuery();
rtnCol = new ArrayList();
while (rs.next()){
getPCls = new CarrierPCls();
getPCls.szCarrierCode = rs.getString("CARRIER_CD");
getPCls.szName=rs.getString("NAME");

rtnCol.add(getPCls);/**/
}
}catch (SQLException ex){
ex.printStackTrace();
}finally{
try {
if (rs != null) rs.close();
if (stat != null) stat.close();
if (conn != null) conn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}
return rtnCol;

}
..
}
public class CarrierPCls {
..
public String szName;
public String szCarrierCode;
..
}
public class TPAControllerBean implements javax.ejb.SessionBean {
..
public ArrayList getCarrierList()
{
ArrayList rtnCol = new ArrayList();
try{
rtnCol = new CarrierDS().findAllCarrier();
}catch (Exception ex) {
ex.printStackTrace();
}
return rtnCol;
}
..
}
public interface TPAController extends javax.ejb.EJBObject{
..
public ArrayList getCarrierList() throws RemoteException;
..
}
Frontend
Carrier.jsp
..
TPAController TPARemote=null;
TPAControllerHome TPAHome=null;
InitialContext initCtx = new InitialContext( );
Object homeObject = initCtx.lookup("java:comp/env/websp/TPAController");
TPAHome = (TPAControllerHome) javax.rmi.PortableRemoteObject.narrow(homeObject, TPAControllerHome.class);
TPARemote = TPAHome.create();
ArrayList resultCol= new ArrayList();
resultCol= TPARemote.getCarrierList();
if (resultCol!=null){
Iterator iteCarrier = resultCol.iterator();
while (iteCarrier.hasNext()) {
CarrierPCls tmpPCls = (CarrierPCls)iteCarrier.next();
out.println(tmpPCls.szCarrierCode + "-----" + tmpPCls.szName + "
");
}
..
[End of source]
There are no compile error and deployment error when I deploy the ejb. But if I call the carrier.jsp on browser, it throw an exception below:
Error 500: RemoteException occurred in server thread; nested exception is: java.rmi.MarshalException: Exception occurred in server thread; nested exception is: java.io.NotSerializableException
the stack list below:
[4/1/04 18:42:05:859 PST] 79deecc9 WebGroup E SRVE0026E: [Servlet Error]-[RemoteException occurred in server thread; nested exception is:
java.rmi.MarshalException: Exception occurred in server thread; nested exception is:
java.io.NotSerializableException]: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.MarshalException: Exception occurred in server thread; nested exception is:
java.io.NotSerializableException
at com.ibm.CORBA.iiop.UtilDelegateImpl.wrapException(UtilDelegateImpl.java:690)
at javax.rmi.CORBA.Util.wrapException(Util.java:295)
at com.websp._TPAController_Stub.getCarrierList(_TPAController_Stub.java:257)
at org.apache.jsp._Carrier._jspService(_Carrier.java:136)
at com.ibm.ws.webcontainer.jsp.runtime.HttpJspBase.service(HttpJspBase.java:89)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at com.ibm.ws.webcontainer.jsp.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:344)
at com.ibm.ws.webcontainer.jsp.servlet.JspServlet.serviceJspFile(JspServlet.java:662)
at com.ibm.ws.webcontainer.jsp.servlet.JspServlet.service(JspServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at com.ibm.ws.webcontainer.servlet.StrictServletInstance.doService(StrictServletInstance.java:110)
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet._service(StrictLifecycleServlet.java:174)
at com.ibm.ws.webcontainer.servlet.ServicingServletState.service(StrictLifecycleServlet.java:333)
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet.service(StrictLifecycleServlet.java:116)
at com.ibm.ws.webcontainer.servlet.ServletInstance.service(ServletInstance.java:283)
at com.ibm.ws.webcontainer.servlet.ValidServletReferenceState.dispatch(ValidServletReferenceState.java:42)
at com.ibm.ws.webcontainer.servlet.ServletInstanceReference.dispatch(ServletInstanceReference.java:40)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.handleWebAppDispatch(WebAppRequestDispatcher.java:974)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:555)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:200)
at com.ibm.ws.webcontainer.srt.WebAppInvoker.doForward(WebAppInvoker.java:119)
at com.ibm.ws.webcontainer.srt.WebAppInvoker.handleInvocationHook(WebAppInvoker.java:276)
at com.ibm.ws.webcontainer.cache.invocation.CachedInvocation.handleInvocation(CachedInvocation.java:71)
at com.ibm.ws.webcontainer.cache.invocation.CacheableInvocationContext.invoke(CacheableInvocationContext.java:114)
at com.ibm.ws.webcontainer.srp.ServletRequestProcessor.dispatchByURI(ServletRequestProcessor.java:186)
at com.ibm.ws.webcontainer.oselistener.OSEListenerDispatcher.service(OSEListener.java:334)
at com.ibm.ws.webcontainer.http.HttpConnection.handleRequest(HttpConnection.java:56)
at com.ibm.ws.http.HttpConnection.readAndHandleRequest(HttpConnection.java:618)
at com.ibm.ws.http.HttpConnection.run(HttpConnection.java:439)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:593)
Caused by: java.rmi.MarshalException: Exception occurred in server thread; nested exception is:
java.io.NotSerializableException
at com.ibm.rmi.util.ProxyUtil.copyObject(ProxyUtil.java:470)
at com.ibm.CORBA.iiop.UtilDelegateImpl.copyObject(UtilDelegateImpl.java:789)
at javax.rmi.CORBA.Util.copyObject(Util.java:332)
at com.websp._TPAController_Stub.getCarrierList(_TPAController_Stub.java:254)
... 27 more
Caused by: java.io.NotSerializableException
... 31 more
P.S. If I change the ArrayList type to Collection in above code, there is a information message prompting "CHKJ2500I: java.util.Collection must be serializable at runtime (EJB 2.0: 7.10.5).". If I use ArrayList, this information message disappear.
Woo! A simple program cause me a lot of time.
Please help! Many thanks!
Raymond
 
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Posts: 3892
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Your CarrierPCls class must implement java.io.Serializable. ALL parameters and return values from an EJB must be serializable, and that includes things included inside of other things.
BTW, ignore the warning about Collection. The ArrayList is Serializable at runtime, so it will work.
Kyle
 
Raymond Ou
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Posts: 34
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Kyle, many many thanks!
I forgot to implement the carrierPCls as serializable! When I correct it, the program runs fine.
Kyle, you are very helpful!
Thanks again!
Raymond
 
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