I discovered that when you build an ALDSP document that contains two related entities, you must take care when you map the join fields to the document. You must map the primary key side of the relationship to the output document. If you map the foreign key side, then you will get a runtime error message like:
com.bea.ld.dsmediator.DataServiceException: Primary key attribute PROPERTY_ID on Object FACT is not provided.
Actually, the rule may be that you have to map the key from the outer element (regardless of which side of the foreign key constraint it comes from). More experimentation is needed.
