em = AppCatalogJPAUtils.getEntityManager();
em.getTransaction().begin();
AppCatalogQueryGenerator generator = new AppCatalogQueryGenerator(COMPUTE_RESOURCE_PREFERENCE);
generator.setParameter(ComputeResourcePreferenceConstants.GATEWAY_ID, ids.get(ComputeResourcePreferenceConstants.GATEWAY_ID));
generator.setParameter(ComputeResourcePreferenceConstants.RESOURCE_ID, ids.get(ComputeResourcePreferenceConstants.RESOURCE_ID));
Query q = generator.selectQuery(em);
ComputeResourcePreference preference = (ComputeResourcePreference) q.getSingleResult();
ComputeHostPreferenceResource preferenceResource =
(ComputeHostPreferenceResource) AppCatalogJPAUtils.getResource(AppCatalogResourceType.COMPUTE_RESOURCE_PREFERENCE, preference);
em.getTransaction().commit();
em.close();