Hello World @OneToMany in a WebService Session Bean

Question

Ladies and Gents,
I'm trying to setup a simple @OneToMany Hello World type example using SOAP based Web Services.  The setup is fairly straightforward: two entities in a parent/child relationship.  Orders is the parent.  OrderRows is the child.  ALL of this was setup with wizards using JDeveloper 11g.  I did not modify the code other than changing the name of the session bean.
The problem occurs when I try to express this relationship by including the @OneToMany annotations and the related List operations (set, add, remove) in the Orders.java file.  If I comment those out and do not return the associated List containing OrderRows, all is well.  Include the @OneToMany and nothing returns.  This is probably some kind of simple configuration error, but the problem is I'm not getting any errors in my console when I right-click my session bean and select "Test Web Service", choose the getOrdersFindAll() operation, and click "Send Request".  All I get is a nice little snarky message saying "No content to display."  So I'm just sitting here ... at 2 AM in the morning ... wondering "Whiskey Tango Foxtrot?"
I've looked over some sites such as http://biemond.blogspot.com/2011/08/expose-your-session-bean-with-jax-ws.html and read through the Java EE 7 tutorial http://docs.oracle.com/javaee/7/tutorial/doc/jaxws.htm#BNAYL all to no avail. 
Does anyone have any ideas?  Or would anyone have some good websites to get some practical examples?
MySessionBean.java
import java.util.List;
    import javax.annotation.Resource;
    import javax.ejb.SessionContext;
    import javax.ejb.Stateless;
    import javax.jws.WebService;
    import javax.persistence.EntityManager;
    import javax.persistence.PersistenceContext;
    @Stateless(name = "MySession", mappedName = "HelloWs-HelloService-MySession")
    @WebService(name = "MySessionBeanService", portName = "MySessionBeanServicePort")
    public class MySessionBean {
        @Resource
        SessionContext sessionContext;
        @PersistenceContext(unitName = "HelloService")
        private EntityManager em;
        public MySessionBean() {
        /** <code>select o from Orders o</code> */
        public List<Orders> getOrdersFindAll() {
            return em.createNamedQuery("Orders.findAll").getResultList();
My Orders.java Entity
  import java.io.Serializable;
    import java.math.BigDecimal;
    import java.util.List;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.Id;
    import javax.persistence.NamedQueries;
    import javax.persistence.NamedQuery;
    import javax.persistence.OneToMany;
    @Entity
    @NamedQueries( { @NamedQuery(name = "Orders.findAll", query = "select o from Orders o")     })
    public class Orders implements Serializable {
        @Id
        @Column(name = "ORDER_ID", nullable = false)
        private BigDecimal orderId;
        @OneToMany(mappedBy = "orders")
        private List<OrderRows> orderRowsList;
        public Orders() {
        public Orders(BigDecimal orderId, String refName) {
            this.orderId = orderId;
        public BigDecimal getOrderId() {
            return orderId;
        public void setOrderId(BigDecimal orderId) {
            this.orderId = orderId;
        public List<OrderRows> getOrderRowsList() {
            return orderRowsList;
        public void setOrderRowsList(List<OrderRows> orderRowsList) {
            this.orderRowsList = orderRowsList;
        public OrderRows addOrderRows(OrderRows orderRows) {
            getOrderRowsList().add(orderRows);
            orderRows.setOrders(this);
            return orderRows;
        public OrderRows removeOrderRows(OrderRows orderRows) {
            getOrderRowsList().remove(orderRows);
            orderRows.setOrders(null);
            return orderRows;
My persistence.xml.  Note that while the double jdbc looks funky, I'm pretty sure that's not the source of the problem since removing the @OneToMany annotation and related methods works.
    <?xml version="1.0" encoding="windows-1252" ?>
    <persistence 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_2_0.xsd"
             version="2.0">
      <persistence-unit name="HelloService">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <jta-data-source>java:/app/jdbc/jdbc/HelloConnDS</jta-data-source>
        <class>helloservice.Orders</class>
        <class>helloservice.OrderRows</class>
        <properties>
          <property name="eclipselink.target-server" value="WebLogic_10"/>
          <property name="javax.persistence.jtaDataSource"     value="java:/app/jdbc/jdbc/HelloConnDS"/>
        </properties>
      </persistence-unit>
    </persistence>
I've also put this question up on stack overflow at http://stackoverflow.com/posts/17769621

Answer 1

Hi, Thomas!
For establishing a connection to R/3 you could either Enterprise Connector (as described in <a href="http://help.sap.com/saphelp_nw04/helpdata/de/ed/897483ea5011d6b2e800508b6b8a93/frameset.htm">Enterprise Connector</a>) or the SAP Resource Adapter (see <a href="http://help.sap.com/saphelp_nw04/helpdata/de/ed/897483ea5011d6b2e800508b6b8a93/frameset.htm">Java Resource Adapter</a>) - the JCA way.
Regards,
Thomas