Re: [hibernate-dev] JPA Compliance

Andrea, SF is a EMF. Unwrapping simply returns the same instance. Another thing I was discussing with Andrea in chat is possibly making these multi-valued, or having multiple values for this. I can't imagine the FQN case is really all that appealing to a user. I'm fairly certain a user would rather simply say "yeah, treat transactions according the JPA spec" as opposed to "here is a class I will provide that will tell will treat transactions according to the JPA spec". We have started to identify some cases where we deviate from the spec[1], such as: * Strict query compliance. As I mentioned earlier we do have such a setting already for this in particular * List versus Bag determination from mappings. * Closed EMF (SF) handling * EntityTransaction status checking - JPA says we should throw exceptions whereas we just ignore the call. We need to decide also which of these we want to just change outright versus controlling via a setting. * Setting * Setting, or introduce a new @Bag annotation - the annotation option is actually pretty appealing since often times the bag behavior is so unexpected from users... * I think we should just change the behavior of calling EMF#close on a closed EMF. Any application that happens to be relying on us no-op'ing this call can easily change that to protect the call with an `#isOpen` check. In fact I think we should change all of these to match the JPA expectations such that it is an error to call any of the following: #close, #getCache, #getMetamodel, #getCriteriaBuilder, #getProperties, #getPersistenceUnitUtil, #createEntityManager. To me these all seem pretty reasonable. And in fact I think we used to handle this all properly from the EMF side. I think we just lost that behavior when we changed to have our contracts extend the JPA ones since we kept the legacy Hibernate behavior in SessionFactory. * This one I am very undecided. I can see very valid arguments for each. [1] we really ought to start keeping a list of these. I have started adding them to the migration guide. Just as a list of things we need to support configuring or switch to the JPA "way". On Fri, Nov 17, 2017 at 11:06 AM andrea boriero <andrea(a)hibernate.org&gt; wrote: > I think for 5.3 it's still fine to rely on isJpaBootstrap may be > documenting that a SF obtained from unwrapping an EMF will conform to the > JPA spec in term of exceptions. > > On 16 November 2017 at 21:09, Vlad Mihalcea <mihalcea.vlad(a)gmail.com&gt; > wrote: > >> When I said multiple modes, I was thinking of defining all these >> situations >> In some interface which declares methods like: >> >> boolean throwsExceptionWhenClosingAClosedEMF() >> >> The interface can have two implementations for Strict JPA and Native >> mode. >> >> However, the setting could take the FQN of the interface implementation, >> so >> a user can define those compatibility methods according to their needs. >> >> E.g. Maybe someone wants the Strict JPA mode but with just 2 differences; >> >> - don't throw exception when closing the ENG twice >> - use the native Hibernate FlushMode.AUTO instead of the JPA one. >> >> Vlad >> >> On 16 Nov 2017 10:49 pm, "Steve Ebersole" <steve(a)hibernate.org&gt; wrote: >> >> > There is already a similar setting, although specific to query >> language: >> > `hibernate.query.jpaql_strict_compliance` - so there is precedence for >> > such a solution. >> > >> > I'm not sure about the "with multiple modes" aspect though. What are >> > these other enumerated mode values? >> > >> > >> > On Thu, Nov 16, 2017 at 2:15 PM Vlad Mihalcea <mihalcea.vlad(a)gmail.com >> > >> > wrote: >> > >> >> Where the JPA way is questionable, let's add one configuration: >> >> hibernate.jpa.compliance with multiple modes: >> >> >> >> - strict: we do whatever the JPA standard says we should do, like >> >> throwing an exception when trying to close the EMF twice >> >> - native: we bend the rule where we don't agree with the standard >> >> >> >> Maybe we should expose all those cases and group them in some >> interface >> >> to allow the user to customize the level of compliance they need. >> >> >> >> Vlad >> >> >> >> On Thu, Nov 16, 2017 at 10:06 PM, Steve Ebersole <steve(a)hibernate.org >> > >> >> wrote: >> >> >> >>> It was added deprecated. Meaning I added it knowing it would go away >> >>> and I wanted to avoid users using it. >> >>> >> >>> BTW, I am talking about a 5.3 release specifically covering 5.2 + JPA >> >>> 2.2. Yes there is a longer term aspect as well with 6.0 and beyond. >> >>> >> >>> Its specifically the "where the JPA way is questionable" aspect I am >> >>> asking about. Like to me, it really never makes sense to throw an >> >>> exception when I close something that is already closed. So how do we >> >>> handle cases like this? >> >>> >> >>> >> >>> On Thu, Nov 16, 2017 at 1:51 PM Vlad Mihalcea < >> mihalcea.vlad(a)gmail.com&gt; >> >>> wrote: >> >>> >> >>>> Hi Steve, >> >>>> >> >>>> I think that for 5.2 was ok to have the isJpaBootstrap method to >> avoid >> >>>> breaking compatibility for the native bootstrap. >> >>>> For 6.0, maybe it's easier if we just align to the JPA spec where it >> >>>> makes sense, >> >>>> and only provide a separation where the JPA way is questionable. >> >>>> >> >>>> I noticed that the isJpaBootstrap method is deprecated. Was it >> >>>> intended to be removed in 6.0? >> >>>> >> >>>> Vlad >> >>>> >> >>>> On Thu, Nov 16, 2017 at 6:21 PM, Steve Ebersole < >> steve(a)hibernate.org&gt; >> >>>> wrote: >> >>>> >> >>>>> Part of 5.2 was merging the JPA contracts into the corresponding >> >>>>> Hibernate >> >>>>> ones. So, e.g., we no longer "wrap" a SessionFactory in an impl of >> >>>>> EntityManagerFactory - instead, SessionFactory now extends >> >>>>> EntityManagerFactory. >> >>>>> >> >>>>> This caused a few problems that we handled as they came up. In >> >>>>> working on >> >>>>> the JPA 2.2 compatibility testing, I see that there are a few more >> >>>>> still >> >>>>> that we need to resolve. Mostly they relate to JPA expecting >> >>>>> exceptions in >> >>>>> certain cases where Hibernate has historically been lenient. >> E.g., JPA >> >>>>> says that calling EntityManagerFactory#close on an EMF that is >> already >> >>>>> closed should result in an exception. Historically, calling >> >>>>> SessionFactory#close on a SF that is already closed is simply >> ignored. >> >>>>> Philosophical debates aside[1], we need to decide how we want to >> handle >> >>>>> this situation such that we can throw the JPA-expected exceptions >> when >> >>>>> needed. Do we simply change SF#close to match the JPA expectation? >> >>>>> Or do >> >>>>> we somehow >> >>>>> make SF#close aware of JPA versus "native" use? This latter option >> >>>>> was the >> >>>>> intent of `SessionFactoryOptions#isJpaBootstrap` and we can >> certainly >> >>>>> continue to use that as the basis of the solution here for other >> cases. >> >>>>> >> >>>>> This `#isJpaBootstrap` flag is controlled by the JPA bootstrap >> code. >> >>>>> So if >> >>>>> the EMF is created in either of the 2 JPA-defined bootstrap >> mechanisms, >> >>>>> that flag is set to true. It's an ok solution, but it does have >> some >> >>>>> limitations - mainly, there was previously a distinction between >> >>>>> SF#close >> >>>>> being called versus EMF#close being called (they were different >> >>>>> classes, so >> >>>>> they could react differently). Therefore, regardless of bootstrap >> >>>>> mechanism, if the user unwrapped the EMF to a SF, they would always >> >>>>> get the >> >>>>> legacy SF behavior. >> >>>>> >> >>>>> So long story short, so we want to consider an alternative >> approach to >> >>>>> deciding what to do in "some"[2] of these cases? Again, we clearly >> >>>>> need >> >>>>> these to throw the spec-mandated exceptions in certain "strict >> >>>>> compliance" >> >>>>> situations. The question really is how to do that. Should we: >> >>>>> >> >>>>> 1. just completely change the behavior to align with the spec? >> >>>>> 2. change the behavior to match the spec *conditionally*, where >> that >> >>>>> condition could be: >> >>>>> 1. `#isJpaBootstrap` >> >>>>> 2. some setting >> >>>>> 3. some extension contract >> >>>>> 4. something else? >> >>>> >> >>>> >> >>>>> >> >>>>> Thoughts? >> >>>>> >> >>>>> >> >>>>> [1] It's not relevant e.g. that I think JPA is wrong here. We >> need to >> >>>>> comply with the spec, at least in certain cases ;) >> >>>>> >> >>>>> [2] I say "some" here, because I think the spec is correct in some >> >>>>> cases - >> >>>>> for example, I think its clearly correct that a closed EMF throws >> an >> >>>>> exception when `#createEntityManager` is called. Personally I >> think >> >>>>> its >> >>>>> questionable whether closing an already closed EMF should be an >> >>>>> exception. >> >>>>> >> >>>> _______________________________________________ >> >>>>> hibernate-dev mailing list >> >>>>> hibernate-dev(a)lists.jboss.org >> >>>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev >> >>>>> >> >>>> >> >>>> >> >> >> _______________________________________________ >> hibernate-dev mailing list >> hibernate-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/hibernate-dev >> > >