Affects Version/s: 2.0.0-M1
Fix Version/s: None
OPENJPA-850, support was provided for some 2.0 spec properties. Some of these properties are equivalent to current openjpa properties, resulting in some properties supported by 2 different keys. As part of this enhancement, an exception is thrown if the same property is specified more than once with different keys. An issue has been raised related to this suggesting that one key could be specified at one level (such as the persistence.xml) but another key could be specified at another level (such as a system property), and that we should allow this. This was discussed among several people, with the resulting conclusion documented by Pinaki as follows:
Rule 1: OpenJPA configurations can be specified at following levels (from lowest to highest)
I have changed Mike's order to reflect how the code (perhaps) now uses precedence (changing such order may require hard tweaks)
> 1. openjpa.xml (globals)
> 5. java.lang.System.getProperties()
> 2. persistence.xml (<properties></properties>)
> 3. A map passed in to the call to createEntityManagerFactory()
> 4. A map passed in to getEntityManager()
Rule 2: Each property is identified by a key. A key must have one, but can have multiple monikers. For example, 'ConnectionDriver' property has two monikers 'openjpa.ConnectionDriverName' and 'javax.persistence.jdbc.driver'. All monikers for a key are treated as interchangeable for all purpose other than when a key appears in the returned list of EMF.getProperties() – which is always the moniker whose corresponding value is 'in effect' in the configuration.
Rule 3: If the same key is specified at the same level, a error message is generated.
Rule 4: If the same key is specified at different levels, the higher level value overwrite the lower level value.
INFO/TRACE message is printed if the values are overwritten or attempted to be overwritten respectively.