EJB - Work with multiple persistence units

[Chris Palau]

Hi guys,

I need to develop an EJB that will work with 4 databases. I am looking in google for the best solution to work with 4 persistence units but I don't have a clear idea about the best solution and the most efficient one.

I dont' know if I inject using @PersistenceUnit() and EntityManagerFactory (one for each of the persistence units) and then create entityManagers using an EntityManagerFactory to choose the EntityManager for the selected persistence unit.

¿If I use 4 @persistentunit injects, will I consume 4 connections to the database ?

Please help.

Thanks !

Chris

[Sebastien Villanueva Thurmes]

Hi,

i am looking for this kind of informations too

i found this interesting link, how to overwrite properties of a PU : Hibernate link see 2.2.2. Bootstrapping

In my case, it should be very nice; i use some schemas in the same DB mysql, the only thing to do should be to override the schema property...

i have not yet tested this trick... i don't know if that work ...

[Sebastien Villanueva Thurmes]

Today, i make some tests:

i work with Netbeans, GlassFish, Derby

persistence.xml

  
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
  <persistence-unit name="CaddyFoxEE-ejbPU" transaction-type="JTA">
    <provider>oracle.toplink.essentials.PersistenceProvider</provider>
    <jta-data-source>jdbc/CaddyFoxWarehouseDS</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="toplink.ddl-generation" value="drop-and-create-tables"/>
    </properties>
  </persistence-unit>
</persistence>
  

my entity bean:

  
@Entity
@Table(name="t_caddyfoxuser")
public class CaddyfoxUser implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    protected String lastname;
    protected String firstname;
    @Column(nullable=false,length=30)
    protected String log;


    public CaddyfoxUser(){

    }


    public  CaddyfoxUser(String first, String last, String log) {
       this.firstname=first;
       this.lastname=last;
       this.log=log;
    }  

my stateless bean:

 
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package com.caddyfox.stateless.caddyfoxuser;

import com.caddyfox.entity.common.CaddyfoxUser;
import com.caddyfox.entity.exception.ValidationException;
import com.caddyfox.util.Constants;
import java.util.logging.Logger;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceUnit;


/**
 *
 * @author seb
 */
@Stateless
public class CaddyfoxUserBean implements CaddyfoxUserRemote, CaddyfoxUserLocal {

 //  @PersistenceContext(unitName="CaddyFoxEE-ejbPU")
   // private EntityManager em;
    @PersistenceUnit(unitName="CaddyFoxEE-ejbPU")
     private EntityManagerFactory emf2;

    private final String cname = this.getClass().getName();
    private Logger logger = Logger.getLogger(Constants.LOGGER_STATELESS);

    public CaddyfoxUserBean() {


    }



    public CaddyfoxUser createCaddyfoxUser(final CaddyfoxUser caddyfoxUser) {
        final String mname = "createCaddyfoxUser";
        logger.entering(cname, mname, caddyfoxUser);

        // On s'assure de la validitÈ des paramËtres
        if (caddyfoxUser == null)
            throw new ValidationException("CaddyfoxUser object is null");


        System.out.println("---seb---test EMF1");
        EntityManagerFactory emf1=null;
        EntityManager em1=null;

        try{
        emf1=Persistence.createEntityManagerFactory("CaddyFoxEE-ejbPU");
        }
        catch(Exception e){
            System.out.println("---seb---ERROR createEntityManagerFactory1:"+e.getMessage());
        }
        

        if (emf1 == null)
            System.out.println("---seb---ERROR emf1 null");

        if (emf1.isOpen())
            System.out.println("---seb---emf1 is opened !!!");
        else
            System.out.println("---seb---ERROR emf is closed !!!");

        try{
        em1=emf1.createEntityManager();
        }
        catch(Exception e){
            System.out.println("---seb---ERROR createEntityManage1:"+e.getMessage());
            }

       try{
       em1.persist(caddyfoxUser);
               }
       catch(Exception e){
            System.out.println("---seb---ERROR persist1:"+e.getMessage());
            }



      System.out.println("---seb---test EMF INJECTION");

       EntityManager em2=null;

      if (emf2 == null)
          System.out.println("---seb---ERROR emf2 null");

      if (emf2.isOpen())
          System.out.println("---seb---emf2 is opened !!!");
      else
          System.out.println("---seb---ERRORemf2 is closed !!!");


      try{
         em2=emf2.createEntityManager();
        }
        catch(Exception e){
            System.out.println("---seb---ERROR createEntityManage2:"+e.getMessage());
            }


       

       try{
    //   em2.persist(caddyfoxUser);
               }
       catch(Exception e){
            System.out.println("---seb---ERROR persist2:"+e.getMessage());
            }

        logger.exiting(cname, mname, caddyfoxUser);



        return caddyfoxUser;
    }



}
  

and my app-client:

  
public class Main {
    @EJB
    private static CaddyfoxUserRemote sb;



    public static void main(String[] args) {
        CaddyfoxUser cfu;

        System.out.println("debut des tests !!!! seb");

        if (sb==null)
            System.out.println("attention sb null");

        cfu=new CaddyfoxUser(args[0],args[1],args[2]);

        try{
         CaddyfoxUser result = sb.createCaddyfoxUser(cfu);
         }
        catch(Exception e){
            System.out.println("problem!!!: "+e.getMessage());
        }
    }

}
  

and the glassfish logs:

  
[#|2009-04-28T13:51:58.782+0200|INFO|sun-appserver2.1|javax.enterprise.system.tools.deployment|_ThreadID=17;_ThreadName=httpWorkerThread-4848-3;|Registering ad hoc servlet: WebPathPath: context root = "/CaddyFoxEE", path = "/CaddyFoxEE-app-client'|#]

[#|2009-04-28T13:51:58.790+0200|INFO|sun-appserver2.1|javax.enterprise.system.tools.deployment|_ThreadID=17;_ThreadName=httpWorkerThread-4848-3;|Java Web Start services started for application com.sun.enterprise.appclient.jws.ApplicationContentOrigin@e79a21 registration name=CaddyFoxEE
    com.sun.enterprise.appclient.jws.NestedAppclientContentOrigin@37f8c9 registration name=CaddyFoxEE, context root=/CaddyFoxEE/CaddyFoxEE-app-client, module name=
, parent=CaddyFoxEE|#]

[#|2009-04-28T13:52:04.298+0200|FINER|sun-appserver2.1|com.caddyfox.stateless|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;ClassName=com.caddyfox.stateless.caddyfoxuser.CaddyfoxUserBean;MethodName=createCaddyfoxUser;com.caddyfox.entity.common.CaddyfoxUser[id=null];_RequestID=9a15e06d-31a0-487a-a8b3-3b50e3f65288;|ENTRY com.caddyfox.entity.common.CaddyfoxUser[id=null]|#]

[#|2009-04-28T13:52:04.299+0200|INFO|sun-appserver2.1|javax.enterprise.system.stream.out|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|
---seb---test EMF1|#]

[#|2009-04-28T13:52:04.301+0200|INFO|sun-appserver2.1|javax.enterprise.system.stream.out|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|
---seb---emf1 is opened !!!|#]

[#|2009-04-28T13:52:04.303+0200|INFO|sun-appserver2.1|oracle.toplink.essentials.session.file:/Users/seb/Documents/CaddyFox/essaiemf/CaddyFoxEE/dist/gfdeploy/CaddyFoxEE-ejb_jar/-CaddyFoxEE-ejbPU|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|TopLink, version: Oracle TopLink Essentials - 2.1 (Build b60e-fcs (12/23/2008))|#]

[#|2009-04-28T13:52:04.303+0200|INFO|sun-appserver2.1|oracle.toplink.essentials.session.file:/Users/seb/Documents/CaddyFox/essaiemf/CaddyFoxEE/dist/gfdeploy/CaddyFoxEE-ejb_jar/-CaddyFoxEE-ejbPU|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|Server: unknown|#]

[#|2009-04-28T13:52:04.304+0200|INFO|sun-appserver2.1|oracle.toplink.essentials.session.file:/Users/seb/Documents/CaddyFox/essaiemf/CaddyFoxEE/dist/gfdeploy/CaddyFoxEE-ejb_jar/-CaddyFoxEE-ejbPU|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|file:/Users/seb/Documents/CaddyFox/essaiemf/CaddyFoxEE/dist/gfdeploy/CaddyFoxEE-ejb_jar/-CaddyFoxEE-ejbPU login successful|#]

[#|2009-04-28T13:52:04.308+0200|INFO|sun-appserver2.1|javax.enterprise.system.stream.out|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|
---seb---test EMF INJECTION|#]

[#|2009-04-28T13:52:04.308+0200|INFO|sun-appserver2.1|javax.enterprise.system.stream.out|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;|
---seb---emf2 is opened !!!|#]

[#|2009-04-28T13:52:04.308+0200|FINER|sun-appserver2.1|com.caddyfox.stateless|_ThreadID=64;_ThreadName=p: thread-pool-1; w: 40;ClassName=com.caddyfox.stateless.caddyfoxuser.CaddyfoxUserBean;MethodName=createCaddyfoxUser;com.caddyfox.entity.common.CaddyfoxUser[id=1];_RequestID=9a15e06d-31a0-487a-a8b3-3b50e3f65288;|RETURN com.caddyfox.entity.common.CaddyfoxUser[id=1]|#]
   

i made a sql request on my table on derby:
select COUNT(*) from DBUSER.T_CADDYFOXUSER

and i have 1 row !!!

select * and i have all i have inserted


That's work whith the two technics:

Persistence.createEntityManagerFactory

EntityManagerFactory INJECTION