The "departments" property is a containment reference - not a simple
cross-reference (pointer). A DataObject can only have a single container,
so SDO specifies that if you add an object to a containment reference, it
is automatically removed from its previous container, if it has one.
You could define a non-containment property and set two of those to point
to a single object, but using it in a way that crosses DataGraphs is also
not allowed. SDO DataGraphs are supposed to be self contained - any
non-containment references in a DataGraph need to point to objects that
are contained in the same DG.
Frank
"Murtaza Goga" <[EMAIL PROTECTED]> wrote on 03/20/2007 12:09:28
PM:
> Maybe I confused the issue with the way I had coded it. I want to add a
> reference to the 'department' object in the two disconnected DataGraphs.
> I was calling DataObject.detach to remove the container reference. The
> test case will fail with the same exception if you comment out the
> detach.
>
> I am not removing objects, I am adding objects. At the end of the test
> case I would have expected to see companyA to have 1 department and
> companyB to have 2 departments. The only way we are able to work around
> this is by making a copy of the object as follows:
>
> for (Iterator iter = departments_A.iterator(); iter.hasNext();) {
> DataObject department_A = (DataObject) iter.next();
> departments_B.add(CopyHelper.INSTANCE.copy(department_A));
> }
>
> This is the failing test code fragment:
> for (Iterator iter = departments_A.iterator(); iter.hasNext();) {
> DataObject department_A = (DataObject) iter.next();
> departments_B.add(department_A);
> }
>
> I hope this clarifies the use case and question.
>
> -----Original Message-----
> From: Frank Budinsky [mailto:[EMAIL PROTECTED]
> Sent: Tuesday, March 20, 2007 11:54 AM
> To: tuscany-user@ws.apache.org
> Subject: Re: ConcurrentModificationException Disconnected DataGraphs
>
> Murtaza,
>
> This is just a standard Java programming issue. You can't remove objects
>
> in a List while you have an active Iterator, unless you use
> Iterator.remove().
>
> In your example, instead of this:
>
> department_A.detach();
>
> you would need to call:
>
> iter.remove();
>
> to remove the department from the list and inform the Iterator of the
> change.
>
> Frank
>
>
> "Murtaza Goga" <[EMAIL PROTECTED]> wrote on 03/20/2007
> 11:24:34
> AM:
>
> > We have two disconnected DataGraphs and when we add DataObjects from
> one
> > DataGraph into the other (with or without 'detach' being called) we
> are
> > observe ConcurrentModificationExceptions. I have pasted a simple test
> > case below which adds a 'department' from one company into another.
> > This test case will error out with the above exception. The
> company.xsd
> > is from the Tuscany M3 RC1 build.
> >
> >
> >
> > Can someone explain this behavior and what should be the recommended
> > usage pattern?
> >
> >
> >
> > /**
> >
> > * @see junit.framework.TestCase#setUp()
> >
> > */
> >
> > @Override
> >
> > protected void setUp() throws Exception {
> >
> > XSDHelper.INSTANCE.define(ClassLoader
> >
> > .getSystemResourceAsStream("company.xsd"), null);
> >
> > }
> >
> >
> >
> > /**
> >
> > * Test list usage.
> >
> > */
> >
> > public void test01Concurrency() {
> >
> > DataGraph dataGraph_A = createCompanyDataGraph(1);
> >
> > DataGraph dataGraph_B = createCompanyDataGraph(1);
> >
> >
> >
> > List departments_A =
> > dataGraph_A.getRootObject().getList("departments");
> >
> > List departments_B =
> > dataGraph_B.getRootObject().getList("departments");
> >
> > for (Iterator iter = departments_A.iterator(); iter.hasNext();) {
> >
> > DataObject department_A = (DataObject) iter.next();
> >
> > department_A.detach(); // Does not matter if this call is made
> or
> > not
> >
> > departments_B.add(department_A);
> >
> > }
> >
> > }
> >
> >
> >
> > /**
> >
> > * Creates the company datagraph.
> >
> > * @param departmentsToCreate the number of departments to create.
> >
> > * @return the DataGraph.
> >
> > */
> >
> > private DataGraph createCompanyDataGraph(int departmentsToCreate) {
> >
> > DataGraph dataGraph = SDOUtil.createDataGraph();
> >
> > dataGraph.createRootObject("company.xsd", "CompanyType");
> >
> > for (int i = 0; i < departmentsToCreate; i++) {
> >
> > dataGraph.getRootObject().createDataObject("departments",
> > "company.xsd",
> >
> > "DepartmentType");
> >
> > }
> >
> > return dataGraph;
> >
> > }
> >
> >
> >
> > Thanks,
> >
> > Murtaza.
> >
>
>
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