users@jpa-spec.java.net

[jpa-spec users] Re: JPA_SPEC-145, JPA_SPEC-146: Provide support for JDK9 module system

From: Linda DeMichiel <linda.demichiel_at_oracle.com>
Date: Wed, 03 May 2017 16:21:15 -0700

Hi,

Since Java EE 8 only requires Java SE 8, JPA 2.2 shouldn't explicitly
define anything related to Java SE 9 modules. (I.e., the
italicized text should not be included in the spec.)

Also, with regard to the second item below (Section 9.2), it isn't
clear how the ServiceLoader facility is intended to be used.
Is this intended as a replacement for the requirements in section 9.3
(Determining the Available Persistence Providers)?
Or is it only intended as a replacement for the behavior of the
default PersistenceProviderResolver in determining the persistence
providers?

thanks,

-Linda


On 5/3/17, 9:13 AM, Lukas Jungmann wrote:
>
> Hi,
>
> Since the release of JDK 9 is behind the corner, it would be good
> to update the spec to be ready for it.
> I can see 2 things which can be done:
>
> 1) JPA_SPEC-145: define module name
>
> I'm not 100% sure this needs to be done but for the sake of
> completeness - it is clear that the module name should be
> 'java.persistence'. While it would be nice to have the name defined
> and available, do we really need this or should we stick with API
> being resolved on JDK9 as an automatic module?
>
> I'm proposing to NOT touch this area in the spec now and keep this up
> to the provider. Any opinions?
>
>
> 2) JPA_SPEC-146: Use ServiceLoader facility
>
> with the introduction of the module system there are currently 2 ways,
> how persistence provider implementation can be defined -
> META-INF/services and module-info with 'provides ... with...'. Former
> way is already covered but the latter is not, so I'd like to propose
> following change to Section 9.2 of the spec (additions are in italics,
> removals are striked-through italics)
>
>
> *Section 9.2 Bootstrapping in Java SE Environments*
>
> In Java SE environments, the Persistence.createEntityManagerFactory
> method is used
> by the application to create an entity manager factory.
>
> A persistence provider implementation running in a Java SE environment
> should also act as a service
> provider by supplying a service provider configuration /file as
> described in the JAR File Specification/. /The Persistence//
> //bootstrap class should use ServiceLoader facility to locate all
> available provider implementations./
>
> The provider configuration /file/ serves to export the provider
> implementation class to the Persistence
> bootstrap class, positioning the provider as a candidate for backing
> named persistence units.
> The provider may supply the provider configuration file by creating a
> text file named javax.persistence.spi.PersistenceProvider
> and placing it in the META-INF/services directory of
> one of its JAR files. The contents of the file should be the name of
> the provider implementation class of
> the javax.persistence.spi.PersistenceProvider interface.
>
> Example/1/:
> A persistence vendor called ACME persistence products ships a JAR
> called acme.jar that contains
> its persistence provider implementation. The JAR includes the provider
> configuration file.
>
> acme.jar
> META-INF/services/javax.persistence.spi.PersistenceProvider
> com.acme.PersistenceProvider
> …
>
> The contents of the
> META-INF/services/javax.persistence.spi.PersistenceProvider
> file is nothing more than the name of the implementation class:
> com.acme.PersistenceProvider.
>
> /Example 2://
> //A persistence vendor called ACME persistence products ships a module
> called acme.jar that provides persistence provider implementation. The
> JAR contains module definition which contains the name of the
> implementation class.//
> //
> //acme.jar//
> // module-info.class//
> // …//
> //
> //module acme {//
> // provides javax.persistence.spi.PersistenceProvider with
> com.acme.PersistenceProvider;//
> // …//
> //}//
> //
> //The source code of the provider's module definition must contain the
> name of the provider’s implementation class./
>
>
> Persistence provider jars may be installed or made available in the
> same ways as other service providers,
> e.g. as extensions/,/or added to the application classpath according
> to the guidelines in the JAR File
> Specification /or added to the application module path according to
> the guidelines in the Java Platform Module System specification/./
> /
>
>
> Do you think this is fine, something should be corrected or is there a
> reason why this second part should not be added to JPA 2.2 MR?
>
> Thank you,
> --lukas
>
> [1]: https://java.net/jira/browse/JPA_SPEC-145
> [2]: https://java.net/jira/browse/JPA_SPEC-146
>