[javaee-spec users] Re: [jpa-spec users] Re: [jsr374-experts] Re: JPA_SPEC-145, JPA_SPEC-146: Provide support for JDK9 module system

From: Kevin Sutter <>
Date: Wed, 3 May 2017 16:24:07 -0500

We should not be incorporating Java SE 9 module definitions into
individual Java EE specifications without the proper guidance from the
Java EE Platform. We have to be consistent with this effort. I know some
of the older Java EE specs that have been incorporated into Java SE have
been defining MRs with the required Java SE 9 updates. But, since Java EE
8 only requires Java SE 8, we should not be defining Java SE 9 module info
in these "child" specifications. This should be a platform requirement
that filters down to the child specs.

Kevin Sutter
STSM, Java EE and Java Persistence API (JPA) architect
e-mail: Twitter: @kwsutter
phone: tl-553-3620 (office), 507-253-3620 (office)

From: Lukas Jungmann <>
Date: 05/03/2017 03:28 PM
Subject: [jpa-spec users] Re: [jsr374-experts] Re: JPA_SPEC-145,
JPA_SPEC-146: Provide support for JDK9 module system

[forgot to cc others in my original reply]

On 5/3/17 9:24 PM, Werner Keil wrote:

Thanks a lot for the pointer especially the JEP and its mention of a
standard namespace for all JCP defined artifacts. That'll help.


On Wed, May 3, 2017 at 7:09 PM, Lukas Jungmann <>
Hi Werner,

On 5/3/17 6:24 PM, Werner Keil wrote:

Thanks for bringing that up.

I was wondering, if there is a common pattern all (Java EE) JSRs are
supposed to follow for making the JSRs Java 9/Jigsaw compatible?

and JSON-P
already got a module-info (at least for JSR 374 it was also you who
created or last changed it;-)

right, I was the one who created it for JSON-P and suggested JSON-B to use
it as well. The idea behind it was that JSON-B is fresh new, simple API
targeted to Java SE 8+ and with JDK 9 release coming it made sense to me
to try to align JSON-B with it ( MR won't be needed later just
because of JDK9). JSON-P was kind of consequence of this since JSON-B
depends on JSON-P...

Unfortunately I don't think there's common pattern to make JSRs Java 9
compatible except of those being part of JDK 9 (eg. JSR-67 (SAAJ), JSR-222
(JAXB) and JSR-224 (JAX-WS) on which I've been working on as well)

As for this spec/JPA 2.2 MR - I'm not strictly against not defining module
name (and I'd actually prefer to define it as soon as provider-agnostic
JPA API artifact becomes available) but since there is currently no
provider-agnostic JPA API artifact, it does not make much sense to me at
this point.

Based on module naming by the JDK itself, should we take
"java.<something>" as a module name to be the preferred name for both the
JDK and all JSRs under

Or are there other preferences e.g. "javax.<something>" to match the Maven
GroupId of most Java EE JSRs especially those by Oracle?
see for JSR 374.

A former EG Member of JSR 363 also asked this in our list and we discussed
what would be a good module name there, but wanted to wait for official
JCP guidance if possible.

the only official naming convention I'm aware of is defined by which states that:

1. Standard modules, whose specifications are governed by the JCP, must
have names starting with the string "java.".

...that should answer your question ;-)


Thanks and Regards,

On Wed, May 3, 2017 at 6:13 PM, Lukas Jungmann <>
   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
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

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.


The contents of the
file is nothing more than the name of the implementation class:

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


module acme {
 provides javax.persistence.spi.PersistenceProvider with

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,