Container managed persistance: many-many relationship

Here's the scenario:
table STUDENTS has columns ID, NAME
table CLASSES has columns ID, TITLE
table STUDENT_CLASSES is an intersection table with columns STUDENT, CLASS which are foreign keys to the ID columns in the STUDENTS and CLASSES tables
How do I specify to OC4J that it should use the STUDENT_CLASSES table to facilitate the container managed many-many relationship?

Voytek -- I would use the ormap demo (projects to emps relationship) as an example and see what exists from deploying that. I've included the original ejb-jar.xml entry as well as a trimmed down version of the orion-ejb-jar.xml entry. In this case it is the default mapping but what you would need to do is include an orion-ejb-jar.xml with just the parts you want to control.
<ejb-relation>
<ejb-relation-name>Emps-Projects</ejb-relation-name>
<ejb-relationship-role>
<ejb-relationship-role-name>Projects-have-Emps</ejb-relationship-role-name>
<multiplicity>Many</multiplicity>
<relationship-role-source>
<ejb-name>ProjectBean</ejb-name>
</relationship-role-source>
<cmr-field>
<cmr-field-name>employees</cmr-field-name>
<cmr-field-type>java.util.Collection</cmr-field-type>
</cmr-field>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>Emps-have-Projects</ejb-relationship-role-name>
<multiplicity>Many</multiplicity>
<relationship-role-source>
<ejb-name>EmpBean</ejb-name>
</relationship-role-source>
<cmr-field>
<cmr-field-name>projects</cmr-field-name>
<cmr-field-type>java.util.Collection</cmr-field-type>
</cmr-field>
</ejb-relationship-role>
</ejb-relation>
<entity-deployment name="ProjectBean" location="ProjectBean" table="ProjectBean" >
<primkey-mapping>
<cmp-field-mapping name="projectNo" persistence-name="projectNo" />
</primkey-mapping>
<cmp-field-mapping name="projectName" persistence-name="projectName" />
<cmp-field-mapping name="employees">
<collection-mapping table="EmpBean_projects_Proje__296v53">
<primkey-mapping>
<cmp-field-mapping name="ProjectBean_projectNo">
<entity-ref home="ProjectBean">
<cmp-field-mapping name="ProjectBean_projectNo" persistence-name="ProjectBean_projectNo" />
</entity-ref>
</cmp-field-mapping>
</primkey-mapping>
<value-mapping type="hr.EmpLocal">
<cmp-field-mapping name="EmpBean_empNo">
<entity-ref home="EmpBean">
<cmp-field-mapping name="EmpBean_empNo" persistence-name="EmpBean_empNo" />
</entity-ref>
</cmp-field-mapping>
</value-mapping>
</collection-mapping>
</cmp-field-mapping>
... finder methods removed ...
</entity-deployment>
I hope this helps -- Jeff

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         <display-name>EJB JAR</display-name>
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              <session>
                   <ejb-name>ProfilerBean</ejb-name>
                   <home>com.atosorigin.tcc.testing.ejbses.profiling.ProfilerHome</home>
                   <remote>com.atosorigin.tcc.testing.ejbses.profiling.Profiler</remote>
                   <local-home>com.atosorigin.tcc.testing.ejbses.profiling.ProfilerLocalHome</local-home>
                   <local>com.atosorigin.tcc.testing.ejbses.profiling.ProfilerLocal</local>
                   <ejb-class>com.atosorigin.tcc.testing.ejbses.profiling.ProfilerBean</ejb-class>
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                   <transaction-type>Container</transaction-type>
                   <ejb-local-ref>
                        <ejb-ref-name>EJBTesting/Solution</ejb-ref-name>
                        <ejb-ref-type>Entity</ejb-ref-type>
                        <local-home>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionLocalHome</local-home>
                        <local>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionLocal</local>
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                        <ejb-ref-type>Entity</ejb-ref-type>
                        <local-home>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantLocalHome</local-home>
                        <local>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantLocal</local>
                        <ejb-link>ConsultantBean</ejb-link>
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                   <ejb-name>ConsultantBean</ejb-name>
                   <home>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantHome</home>
                   <remote>com.atosorigin.tcc.testing.ejbcmp.profiling.Consultant</remote>
                   <local-home>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantLocalHome</local-home>
                   <local>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantLocal</local>
                   <ejb-class>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantBean</ejb-class>
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                   <prim-key-class>java.lang.String</prim-key-class>
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                   <cmp-version>2.x</cmp-version>
                   <abstract-schema-name>Consultant</abstract-schema-name>
                   <cmp-field>
                        <field-name>firstname</field-name>
                   </cmp-field>
                   <cmp-field>
                        <field-name>lastname</field-name>
                   </cmp-field>
                   <cmp-field>
                        <field-name>country</field-name>
                   </cmp-field>
                   <cmp-field>
                        <field-name>id</field-name>
                   </cmp-field>
                   <primkey-field>id</primkey-field>
                   <query>
                        <query-method>
                             <method-name>findBySolution</method-name>
                             <method-params>
                                  <method-param>java.lang.String</method-param>
                             </method-params>
                        </query-method>
                        <ejb-ql>SELECT Object(c) FROM Consultant AS c,
                        IN(c.solutions) s WHERE s.id = ?1 </ejb-ql>
                   </query>
              </entity>
              <entity>
                   <ejb-name>SolutionBean</ejb-name>
                   <home>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionHome</home>
                   <remote>com.atosorigin.tcc.testing.ejbcmp.profiling.Solution</remote>
                   <local-home>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionLocalHome</local-home>
                   <local>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionLocal</local>
                   <ejb-class>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionBean</ejb-class>
                   <persistence-type>Container</persistence-type>
                   <prim-key-class>java.lang.String</prim-key-class>
                   <reentrant>False</reentrant>
                   <cmp-version>2.x</cmp-version>
                   <abstract-schema-name>Solution</abstract-schema-name>
                   <cmp-field>
                        <field-name>description</field-name>
                   </cmp-field>
                   <cmp-field>
                        <field-name>name</field-name>
                   </cmp-field>
                   <cmp-field>
                        <field-name>parent</field-name>
                   </cmp-field>
                   <cmp-field>
                        <field-name>id</field-name>
                   </cmp-field>
                   <primkey-field>id</primkey-field>
                   <query>
                        <query-method>
                             <method-name>findChildSolutions</method-name>
                             <method-params>
                                  <method-param>java.lang.String</method-param>
                             </method-params>
                        </query-method>
                        <ejb-ql>SELECT Object(s) FROM Solution AS s WHERE
                        s.parent = ?1</ejb-ql>
                   </query>
                   <query>
                        <query-method>
                             <method-name>findTopLevelSolutions</method-name>
                             <method-params/>
                        </query-method>
                        <ejb-ql>Select Object(s) FROM Solution AS s WHERE
                        (s.parent = &apos;none&apos;)</ejb-ql>
                   </query>
              </entity>
         </enterprise-beans>
         <relationships>
              <ejb-relation>
                   <description>A consultant may have one or more areas of expertise</description>
                   <ejb-relation-name>Consultant_Solutions</ejb-relation-name>
                   <ejb-relationship-role>
                        <ejb-relationship-role-name>com.atosorigin.tcc.testing.ejbcmp.profiling.ConsultantBean</ejb-relationship-role-name>
                        <multiplicity>Many</multiplicity>
                        <relationship-role-source>
                             <ejb-name>ConsultantBean</ejb-name>
                        </relationship-role-source>
                        <cmr-field>
                             <cmr-field-name>solutions</cmr-field-name>
                             <cmr-field-type>java.util.Collection</cmr-field-type>
                        </cmr-field>
                   </ejb-relationship-role>
                   <ejb-relationship-role>
                        <ejb-relationship-role-name>com.atosorigin.tcc.testing.ejbcmp.profiling.SolutionBean</ejb-relationship-role-name>
                        <multiplicity>Many</multiplicity>
                        <relationship-role-source>
                             <ejb-name>SolutionBean</ejb-name>
                        </relationship-role-source>
                   </ejb-relationship-role>
              </ejb-relation>
         </relationships>
         <assembly-descriptor>
              <container-transaction>
                   <description>container-transaction</description>
                   <method>
                        <ejb-name>SolutionBean</ejb-name>
                        <method-name>*</method-name>
                   </method>
                   <method>
                        <ejb-name>ProfilerBean</ejb-name>
                        <method-name>*</method-name>
                   </method>
                   <method>
                        <ejb-name>ConsultantBean</ejb-name>
                        <method-name>*</method-name>
                   </method>
                   <trans-attribute>Required</trans-attribute>
              </container-transaction>
         </assembly-descriptor>
    </ejb-jar>
    I created a stateless session bean as a business facade for the two entity beans. I then created a webservice to test the beans.
    What works :
    - create a consultant
    - get a consultant
    - create a solution
    - get a solution
    (basically everything that doesn't involve the relationship field.
    However, what doesn't work is the method call assignSolution:
    - assign solution : this is implemented as follows
    Business Method.
         public void assignSolution(String consultantID, String solutionID)
              throws ProfilingException {
              // TODO : Implement
              ConsultantLocal cons = null;
              SolutionLocal sol = null;
              try {
                   cons = consHome.findByPrimaryKey(consultantID);
                   sol = solHome.findByPrimaryKey(solutionID);
                   Collection solutions = cons.getSolutions();
                   solutions.add(sol);
                   //sol.getConsultants().add(cons);
              } catch (FinderException ex) {
                   ex.printStackTrace();
                   throw new ProfilingException("failed to retrieve data from DB", ex);
    As you can see I am trying to use the CM Relationship in this methhod. Adding the solution to a consultant should be as simple as adding a solution object to the collection retrieved with the getSolutions accessor. The Container is expected to persist the information in my MAXDB database.
    However this doesn't happen.
    The ORM details as defined in the persistent.xml follows :
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE persistent-ejb-map SYSTEM "persistent.dtd">
    <persistent-ejb-map>
         <locking
              type="Table"/>
         <db-properties>
              <data-source-name>TCC_PORTAL_PROFILER</data-source-name>
              <database-vendor
                   name="SAPDB"/>
         </db-properties>
         <entity-beans>
              <entity-bean>
                   <ejb-name>ConsultantBean</ejb-name>
                   <table-name>PFL_CONSULTANTS</table-name>
                   <field-map
                        key-type="NoKey">
                        <field-name>firstname</field-name>
                        <column>
                             <column-name>FIRSTNAME</column-name>
                        </column>
                   </field-map>
                   <field-map
                        key-type="NoKey">
                        <field-name>lastname</field-name>
                        <column>
                             <column-name>LASTNAME</column-name>
                        </column>
                   </field-map>
                   <field-map
                        key-type="NoKey">
                        <field-name>country</field-name>
                        <column>
                             <column-name>COUNTRY</column-name>
                        </column>
                   </field-map>
                   <field-map
                        key-type="PrimaryKey">
                        <field-name>id</field-name>
                        <column>
                             <column-name>ID</column-name>
                        </column>
                   </field-map>
                   <finder-descriptor>
                        <method-name>findBySolution</method-name>
                        <method-params>
                             <method-param>java.lang.String</method-param>
                        </method-params>
                        <load-selected-objects
                             lock="read"/>
                   </finder-descriptor>
              </entity-bean>
              <entity-bean>
                   <ejb-name>SolutionBean</ejb-name>
                   <table-name>PFL_SAPSOLUTIONS</table-name>
                   <field-map
                        key-type="NoKey">
                        <field-name>description</field-name>
                        <column>
                             <column-name>DESCRIPTION</column-name>
                        </column>
                   </field-map>
                   <field-map
                        key-type="NoKey">
                        <field-name>name</field-name>
                        <column>
                             <column-name>NAME</column-name>
                        </column>
                   </field-map>
                   <field-map
                        key-type="NoKey">
                        <field-name>parent</field-name>
                        <column>
                             <column-name>PARENTID</column-name>
                        </column>
                   </field-map>
                   <field-map
                        key-type="PrimaryKey">
                        <field-name>id</field-name>
                        <column>
                             <column-name>ID</column-name>
                        </column>
                   </field-map>
                   <finder-descriptor>
                        <method-name>findChildSolutions</method-name>
                        <method-params>
                             <method-param>java.lang.String</method-param>
                        </method-params>
                        <load-selected-objects
                             lock="read"/>
                   </finder-descriptor>
                   <finder-descriptor>
                        <method-name>findTopLevelSolutions</method-name>
                        <method-params/>
                        <load-selected-objects
                             lock="read"/>
                   </finder-descriptor>
              </entity-bean>
         </entity-beans>
         <relationships>
              <table-relation>
                   <help-table>PFL_CONS_SOL_MAP</help-table>
                   <table-relationship-role
                        key-type="PrimaryKey">
                        <ejb-name>ConsultantBean</ejb-name>
                        <cmr-field>solutions</cmr-field>
                        <fk-column>
                             <column-name>CONSULTANTID</column-name>
                             <pk-field-name>id</pk-field-name>
                        </fk-column>
                   </table-relationship-role>
                   <table-relationship-role
                        key-type="PrimaryKey">
                        <ejb-name>SolutionBean</ejb-name>
                        <fk-column>
                             <column-name>SOLUTIONID</column-name>
                             <pk-field-name>id</pk-field-name>
                        </fk-column>
                   </table-relationship-role>
              </table-relation>
         </relationships>
    </persistent-ejb-map>
    The error in the default trace file when calling the method states, there is an "inconsistency in the number of primary keys". Details follow.
    #1.5#000F1F188E5C004400000000000010480003E76C80EFD57A#1098880364327#com.sap.engine.services.ejb#com.atosorigin.tcc/EJBCMPProfilingTest#com.sap.engine.services.ejb#Guest#2####4d2b2370281411d9a40d000f1f188e5c#SAPEngine_Application_Thread[impl:3]_31##0#0#Error##Java###
    [EXCEPTION]
    #1#com.sap.engine.services.ejb.exceptions.BaseRemoteException: Exception in method assignSolution.
         at com.atosorigin.tcc.testing.ejbses.profiling.ProfilerObjectImpl0.assignSolution(ProfilerObjectImpl0.java:822)
         at com.atosorigin.tcc.testing.ejbses.profiling.Profiler_Stub.assignSolution(Profiler_Stub.java:533)
         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
         at java.lang.reflect.Method.invoke(Method.java:324)
         at com.sap.engine.services.ejb.session.stateless_sp5.ObjectStubProxyImpl.invoke(ObjectStubProxyImpl.java:187)
         at $Proxy73.assignSolution(Unknown Source)
         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
         at java.lang.reflect.Method.invoke(Method.java:324)
         at com.sap.engine.services.webservices.runtime.EJBImplementationContainer.invokeMethod(EJBImplementationContainer.java:126)
         at com.sap.engine.services.webservices.runtime.RuntimeProcessor.process(RuntimeProcessor.java:146)
         at com.sap.engine.services.webservices.runtime.RuntimeProcessor.process(RuntimeProcessor.java:68)
         at com.sap.engine.services.webservices.runtime.servlet.ServletDispatcherImpl.doPost(ServletDispatcherImpl.java:92)
         at SoapServlet.doPost(SoapServlet.java:51)
         at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
         at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
         at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.runServlet(HttpHandlerImpl.java:385)
         at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.handleRequest(HttpHandlerImpl.java:263)
         at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java:339)
         at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java:317)
         at com.sap.engine.services.httpserver.server.RequestAnalizer.invokeWebContainer(RequestAnalizer.java:810)
         at com.sap.engine.services.httpserver.server.RequestAnalizer.handle(RequestAnalizer.java:238)
         at com.sap.engine.services.httpserver.server.Client.handle(Client.java:92)
         at com.sap.engine.services.httpserver.server.Processor.request(Processor.java:147)
         at com.sap.engine.core.service630.context.cluster.session.ApplicationSessionMessageListener.process(ApplicationSessionMessageListener.java:37)
         at com.sap.engine.core.cluster.impl6.session.UnorderedChannel$MessageRunner.run(UnorderedChannel.java:71)
         at com.sap.engine.core.thread.impl3.ActionObject.run(ActionObject.java:37)
         at java.security.AccessController.doPrivileged(Native Method)
         at com.sap.engine.core.thread.impl3.SingleThread.execute(SingleThread.java:94)
         at com.sap.engine.core.thread.impl3.SingleThread.run(SingleThread.java:162)
    Caused by: com.sap.engine.services.applocking.exception.SAPAppLockingIllegalArgumentException: Inconsistency in number of primary keys
         at com.sap.engine.services.applocking.TableLockingImpl.getArgument(TableLockingImpl.java:385)
         at com.sap.engine.services.applocking.TableLockingImpl.lock(TableLockingImpl.java:128)
         at com.sap.engine.services.applocking.TableLockingImpl.lock(TableLockingImpl.java:138)
         at com.sap.engine.services.ejb.entity.pm.lock.TableLockingSystem.write(TableLockingSystem.java:82)
         at com.sap.engine.services.ejb.entity.pm.PersistentM2M.create(PersistentM2M.java:172)
         at com.sap.engine.services.ejb.entity.pm.PersistentCacheM2M.add(PersistentCacheM2M.java:197)
         at com.sap.engine.services.ejb.entity.pm.multiple.CollectionM2M.add(CollectionM2M.java:57)
         at com.atosorigin.tcc.testing.ejbses.profiling.ProfilerBean.assignSolution(ProfilerBean.java:201)
         at com.atosorigin.tcc.testing.ejbses.profiling.ProfilerObjectImpl0.assignSolution(ProfilerObjectImpl0.java:771)
         ... 32 more
    I can't figure out what the problem is with the ORM mapping defined.
    On the database level I have three tables. Consultant maps to PFL_CONSULTANT, Solution to PFL_SAPSOLUTIONS. The third table PFL_CONS_SOL_MAP is the help table used for the relationship (having two fields, which are in fact foreign keys from the other two tables to express the assignment of solutions to consultants (where a consultant can have one or more solutions).
    ps. : I am running Netweaver Developer Workplace (Netweaver 2004, at stack level 5)
    Message was edited by: Theo Paesen

    Hm, after disabling 'automatic locking' it works.

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  • Problem with 1-to-many relationship between entity beans

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    CHILD-NAME
    PARENT-ID(foreign key of PARENTID).
    ejbCreate(Integer parentID,String name,String foreignparentID)
    In a jsp page i collect the parent details and 3 corresponding chld details in a text box.
    Can you please tell me how do i proceed from here...
    ie. how to i insert data into the entity beans..
    Do i pass the child as a collection, and within parents ejbCreate() method do i lookup for the childs home interface and insert one -by -one from the collection.
    1. Considering the above example, can some one pls tell how the ejbCreate() mehod signatures, for the parent and child entity beans should be.
    2. Pls also show some sample client code as to how to make an insertion.
    3. In case you are passing a collection of child data, then in what format does one have to insert into a collection and also how does the container know how to insert the values in the child table , bcoz we are passing as a collection.
    4.In case collections cannot be inserted do we need to iterate into the collection in parent's ejbCreate() method, and manually insert into the database of the childtable, thereby creating child entity beans.
    Thanks for your time and support...
    regards
    kartik

    Hi,
    3. In this case of course child's ejbCreate(and postCreate) looks like
    ejbCreate(Integer childID,String name,ParentLocal parent) {
    setId(Id);
    setName(name);
    ejbPostCreate(Integer childID,String name,ParentLocal parent) {
    setParent(parent);
    Here you don't need IDs, but it happens only using Locals, not Remotes, if I'm not wrong. Container does it itself.
    1. Of course, if you have parent.getChildren() and parent.setChildren() then you don't need any loops, but it should be done anyway in postCreate, because in ejbCreate there no parent exists yet.
    Once more 3: example - I'm using JBoss 3.2.5 as EJB container. It has tomcat inside and EJB and JSP+Struts use the same jvm. It means for me that I don't need to use remote interfaces, just locals. And in this case I can implement ejb-relations. So, a have the abstract method parent.getChildren() which returns Collection of ChildLocal - s and method parent.setChildren(Collection childrenLocals) which creates/modifies children by itself.
    I have not used remotes for a long time, but as I remember it was not possible to implement ejb-relations using remotes.
    regards,
    Gio

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