[ http://issues.apache.org/jira/browse/OPENJPA-24?page=comments#action_12436323 ] Michael Dick commented on OPENJPA-24: -------------------------------------
Thanks Abe, I was able to load a custom EMF with your changes. I might have more questions when I get a chance to experiment a little more. > Allow OpenJPA to be extensible > ------------------------------ > > Key: OPENJPA-24 > URL: http://issues.apache.org/jira/browse/OPENJPA-24 > Project: OpenJPA > Issue Type: Bug > Components: kernel > Reporter: Kevin Sutter > Assigned To: Kevin Sutter > > The current OpenJPA architecture is not extendable to other implementations. > For example, if somebody wanted to provide their own PersistenceProvider > implementation, simply extending the > org.apache.openjpa.PersistenceProviderImpl would not suffice due to the > dependencies in the ConfigurationProviderImpl. The discussion for this > improvement was started on the dev mailing list. Once it was determined that > there was more to this request than a simple conditional or two, we decided > to open a JIRA report. > The complete history of this request can be found in the OpenJPA dev mailing > list. The first message was posted by me (Kevin Sutter) on August 14, titled > "Extending the OpenJPA Implementation". I will attempt to paraphrase the > current state of the problem... > We have three main players in this issue. The PersistenceProvider, the > ConfigurationProvider, and the ProductDerivation (along with the various > implementations of these interfaces). Currently, the ConfigurationProvider > is in the lib and is unaware of any specific persistence requirements. The > ProductDerivation is in the kernel and, unfortunately, is aware of > persistence requirements, specifically the spec and store types. Abe's > postings have indicated that we need to make these two interfaces more aware > of each other and work with each other. We need to start with either making > ConfigurationProvider more persistence-aware and move it into kernel, or make > ProductDerivations less persistence-aware and move it into lib. The latter > approach is preferred. > After we get this re-organization of the base framework complete, we still > have a couple of other issues ot resolve: > * Still need the ability to extend EMF's through a ProductDerivation. > This should be doable by adding a new PluginValue to indicate what class of > EMF to load. > * There is still a question as to whether we will need to provide a > custom PersistenceProviderImpl and ConfigurationProviderImpl pair. I still > think this will be necessary. And, one of Abe's posts indicated that this > might help with class loading issues when multiple versions of OpenJPA-based > implementations are available in the same system. > I also posted these questions last Friday. (Abe has responded with some > answers, but I wanted to get this JIRA report created before trying to > paraphrase his answers.) > * You mention in several places about separating away the notion of > specs and stores. In a general sense, I understand what these are. But, can > you elaborate on how these types are used in the ConfigurationProvider and > ProductDerivation interfaces? > * I've moved the ProductDerivation interface to the lib and added the > "load" methods from the ConfigurationProvider (as described in your previous > notes). And, I've started to clean up the implementations that depend on > these interfaces. But, concerning the implementation of the load methods... > Now that we need to return a ConfigurationProvider, would you expect that we > just new up a ConfigurationProviderImpl and then just call across to the > "load" methods on the implementation? Since we want to keep the > ProductDerivations stateless, I'm not sure how else you were expecting to > create a ConfigurationProvider to return on these "load" methods. > * Now that ConfigurationProvider is bare, the > ConfigurationTestConfigurationProvider doesn't have much function. I'll need > to take a look to see if this is even required any longer. > * Can you shed a bit more light on the Configurations class? It doesn't > implement nor extend any interfaces or classes, but it seems to provide many > of the same methods as ConfigurationProvider, but as statics. And, it's > dependent on having a Provider. Can you explain the relationship of this > class in the bigger picture and how you think it might be affected by thes > changes? > That's enough for the initial JIRA report. We will now track this problem > here instead of the dev mailing list. Thanks. > Kevin -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
