Toplink API

[Dominik Müller]

Hi all together,

i am really weired about the Toplink API and how to use it.
Until now, i used the JPA Implementation from Toplink (with an Entity Manager). My (far far away) Finish is a little Online-Offline WebStart client with DataSync mechanism.
For this Reason i search the web a littlebit and foud some manuals about the "Toplink API", which in my understanding offers a little bit more functionality then the JPA defaults (in fact the "UnitOfWork" seems pretty nice for my application).

Here my "old" EntityManager Project (which connects to the Offline = local Derby-DB), which i want to rebuild with the Toplink API instead.
Entity

@Entity
public class Kunde implements Serializable {
	@Id
	private Integer id;
	private String vorname;
	private String nachname;
	private Timestamp changeDate;

//+ getters/setters

My OfflinePU

    
	<persistence-unit name="PUOffline" transaction-type="RESOURCE_LOCAL">
		<provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>
		<class>dd.webstart.jpa.Kunde</class>
		<properties>
			<property name="toplink.jdbc.url" value="jdbc:derby:db/web;create=true"/>
			<property name="toplink.jdbc.user" value="root"/>
			<property name="toplink.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver"/>
			<property name="toplink.jdbc.password" value=""/>
			<property name="toplink.ddl-generation" value="create-tables"/>
		</properties>
	</persistence-unit>

and a little CodeSnipped:

		em=Persistence.createEntityManagerFactory(pu).createEntityManager();
		em.createQuery("select k from Kunde k").getResultList();

** works fins **

now i try to build up the connection with the Toplink API instead, but i am too stupid i think ;) Same datasource as above

		DatabaseLogin dbLogin=new DatabaseLogin();
// This won't work too
//		dbLogin.setProperty("toplink.jdbc.url", "jdbc:derby:db/web;create=true");
//		dbLogin.setProperty("toplink.jdbc.user", "root");
//		dbLogin.setProperty("toplink.jdbc.driver", "org.apache.derby.jdbc.EmbeddedDriver");
//		dbLogin.setProperty("toplink.jdbc.password", "");
//		dbLogin.setProperty("toplink.ddl-generation", "create-tables");
		
		dbLogin.setDatabaseURL("jdbc:derby:db/web;create=true");
		dbLogin.setUserName("root");
		dbLogin.setPassword("");
		dbLogin.setDriverClass(org.apache.derby.jdbc.EmbeddedDriver.class);
		
		session=new DatabaseSessionImpl(dbLogin);
		session.setLogin(dbLogin);
		session.connect();

Error says, that he can't found the datasource and no default driver???

In Toplink Manual i read in addition somethink about the a project.xml, which can be used to read all the configuration aboute the connection from a xml file:

Example 76-6 illustrates creating a DatabaseSession using a Project read in from a project.xml file. 

Example 76-6 Creating a Database Session from a project.xml File Project
Project myProject = XMLProjectReader.read("myproject.xml");
DatabaseSession databaseSession = myProject.createDatabaseSession();

but a) the "XMLProjectReader" seems not be present for toplink-essentials and b) i find nowhere a documentation how to build up such a project.xml

Maybe i am running in the complete wrong direction, hope somebody could show me the right way ;)

thanks a lot
Dom

[James Sutherland]

In your login you need to call, setConnectionString, not setDatabaseURL.

TopLink Essentials does not support the project.xml, but if you upgrade to EclipseLink (TopLink 11g), everything is supported.

In general I would recommend using JPA, not the native TopLink API. You can still use JPA and access the UnitOfWork API when required. You can get a UnitOfWork from an EntityManager, or create one from an EntityManagerFactory's ServerSession.

[Bear Bibeault]

"da dom", please check your private messages for an important administrative matter.

[Dominik Müller]

James Sutherland wrote: You can get a UnitOfWork from an EntityManager

I found the "getActiveSession()" from EntityManager, this seems to be the best way, but my Problem is that i use the EntityManager (as shown above) from javax.persistence.Persistence; . The additional functions to get the active Session and aquire a unit of work just seems to be present for the entitymanager from Toplink self. The Problem is to get an Toplink-Entitymanager, i need the Factory, the Toplink-EntityManagerFactory need a ServerSession to create, and i am at the same position as above . Or is there any opportunity to get the Session/UoW from the javax.persistence.Persistence.EntityManager; or "convert" this EntityManager in a Toplink-One?

Thanks a lot
Dominik

[James Sutherland]

You can just cast the EntityManager interface to the EclipseLink/TopLink JpaEntityManager. If using JEE, you will need to first call getDelegate().