Right approach using EntityManager and MDB

[hispeedsurfer]

Hi

I have not much experience with MDBs.

I need to use EntityManager in combination with a MDB. As I have seen here in forum an other user have used this in the same way as follow:

MDB

package de.oats.business.mdb;

import javax.annotation.Resource;
import javax.ejb.ActivationConfigProperty;
import javax.ejb.MessageDriven;
import javax.ejb.MessageDrivenContext;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.ObjectMessage;

import org.jboss.annotation.ejb.PoolClass;
import org.jboss.seam.annotations.In;


@MessageDriven(name="QueryMessageBean", activationConfig = {
 @ActivationConfigProperty(propertyName="destinationType", propertyValue="javax.jms.Queue"),
 @ActivationConfigProperty(propertyName="destination", propertyValue="queue/oatsMessageQueue")

})
@PoolClass(value=org.jboss.ejb3.StrictMaxPool.class, maxSize=1)
public class QueryMessageBean implements MessageListener {

 @Resource
 private MessageDrivenContext context;
 @In(create=true)
 private UserQuery userquery;

 public void onMessage(Message message) {
 QueryTest name = null;

 try {
 if (message instanceof ObjectMessage) {
 ObjectMessage objMessage = (ObjectMessage) message;
 Object obj = objMessage.getObject();
 if (obj instanceof QueryTest) {
 name = (QueryTest) obj;
 userquery.setSqlQuery(name.getSqlQuery());
 userquery.query();
 } else {
 System.err.println("Expecting ProcessDTO in Message");
 }
 } else {
 System.err.println("Expecting Object Message");
 }
 } catch (Throwable t) {
 t.printStackTrace();
 context.setRollbackOnly();
 }
 }
}

SLSB

package de.oats.business.mdb;

import java.io.Serializable;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Date;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.jboss.seam.annotations.In;
import org.jboss.seam.annotations.Name;

import de.oats.model.QueryResult;

@Stateless
@Name("userQuery")
public class UserQueryBean implements UserQuery{

 private String sqlQuery;

 private static Connection con = null;
 @PersistenceContext
 private EntityManager entityManager;

 public UserQueryBean() {
 super();
 }

 public String query(){
 ResultSet rs;
 Statement stmt;
 try {
 con = MysqlCon.getConnection();
 stmt = con.createStatement();

 rs = stmt.executeQuery(sqlQuery);
 QueryResult qrslt = null;
 while(rs.next()){
 qrslt = new QueryResult();
 qrslt.setAnzahl(rs.getLong("anzahl"));
 qrslt.setY20gpnum(rs.getString("y20gpnum"));
 qrslt.setLat(rs.getDouble("lat"));
 qrslt.setLon(rs.getDouble("lon"));

 entityManager.persist(qrslt);
 }
 entityManager.flush();
 } catch (Exception e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 return "5 seconds for " +kindOfQuery;
 }
 public void setSqlQuery(String sqlQuery) {
 this.sqlQuery = sqlQuery;
 }

}

But userquery is always null in spite of @In(create=true)

An other try was to put EntityManager in the ObjectMessage(UserTest) - here is null value on entityManager.

Use Seam 2.0 (seam generatet project) and jboss-4.2.1.GA

[pmuir]

QueryMessageBean isn't a Seam component, it needs @Name on it.