Re: [hibernate-dev] JPA Compliance

On 24 November 2017 at 17:39, Steve Ebersole <steve(a)hibernate.org&gt; wrote: > Andrea, SF is a EMF. Unwrapping simply returns the same instance. > yes but has you pointed out due to the bootstrapping the behaviour of the SF will be strict JPA compliant. > > 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... > @Bag seems really a good idea to me but that means changing the current default behaviour, forcing users to change the code, so not sure if we need also a setting. > * 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. > I do not like the EMF#close behaviour, probably a prefer a separate setting for this. > * This one I am very undecided. I can see very valid arguments for each. > probably for such case a setting may be a good option. > > [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&gt; >>> > 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&gt; >>> >> 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 >>> >> >>