The great thing is that DS is not an "API" you use, it is just a convenient way to express what you provide and what you need, so you will never have any runtime dependency and thus can always choose another, you can even code all this "by hand" ... anyways I never heard it is "superseeded" or "legacy" do you have any normative statement about that?

> maven has a well defined lifecycle whereas OSGi wants to be ultra dynamic

OSGi can be used in a dynamic way but still has "well defined lifecycle" and you are not forced to use the dynamics. and you can define the maven-lifecycle on top of it OSGi do not mandates any specific way to use it. e.g. Tycho embedds OSGi into maven, while m2eclipse do the other way round: Running in OSGi and embedding maven ...

> but almost untestable without sophisticated
> solutions for enterprises apps)

OSGi actually allows better testing (through DI and service layer), while the official maven-plugin-test still suffers from being bound to maven-compat and JUnit 3 .... so I can't really say testing "maven" is really anything I would call easy ;-)

> we should just stick to the excellent work Guillaume did and keep
> decoupling our internal impls/deps from the exposed API we should
> keep control now we have a real API we lacked for years.

This work is actually nothing contradictory or "different" if one would use OSGi ...


Am 17.11.22 um 19:58 schrieb Romain Manni-Bucau:
Le jeu. 17 nov. 2022 à 19:23, Christoph Läubrich <m...@laeubi-soft.de> a
écrit :

For OSGi there is a DI framework name "Declarative Services", that is
(from users POV) not any "complex" or different than Plexus, e.g a Mojo
might simply look like:

@Component
MyMojo implements Mojo {

     @Reference
     Logger logger;

     @Overide
     void execute() {
       ... do it ! ...
     }
}

for the rest, you simply has a maven plugin that generates all the rest
for you ... so very similar to what we have today, but with much more
flexibility (not shown here as not required for most cases).

And for the "breakage", as outlined in the linked issue [1], Tycho
already use a Maven <-> OSGi bridge, so actually one can even combine
both "worlds" ...


We saw multiple times by the past we shouldn't expose any used API cause it
leads to conflicts, API incompatibilities etc... so reuse DS sounds like
redoing some previous errors (we got bitten by a single annotation from
cdi-api.jar so imagine if we use more ;)).
Also DS is starting to be legacy now OSGi superseeded it by OSGi-CDI so not
sure it is better than going back to plexus for end users.
Last issue is that it has a whole set of API for dynamism maven will not
get (to not make the system overcomplex and since it has no real need of it
- maven has a well defined lifecycle whereas OSGi wants to be ultra dynamic
which is good for some systems but almost untestable without sophisticated
solutions for enterprises apps) so think we should just stick to the
excellent work Guillaume did and keep decoupling our internal impls/deps
from the exposed API we should keep control now we have a real API we
lacked for years.



[1] https://issues.apache.org/jira/browse/MNG-7518

Am 17.11.22 um 17:48 schrieb Guillaume Nodet:
I do agree that debugging the provisioning side is *very* complicated
when
there's a problem.
I'd be happy to get rid of sisu/plexus and use a more simple DI
framework,
at least for simple plugins.
However, I definitely don't think pushing OSGi to plugins would be a good
idea : the cost and burden on plugin developers would outweigh the
benefits.

For extensions, and for maven itself, that is a different story though.
Maven and extensions could definitely benefit from OSGi, but this would
be
a complete breakage and it would be hard to keep some level of
compatibility.

Le jeu. 17 nov. 2022 à 17:00, Christoph Läubrich <m...@laeubi-soft.de> a
écrit :

   > Guess classrealm is fine for maven, it does not bring much issues

As long as it works, maybe, maybe even if you write a simple maven
plugin, but for any more complex it is just a complete mess.

Last time I asked on the mailing list how to debug that stuff ...
complete silence ...

Today I tried to refactor the name of one module of a more complex
maven-plugin (with core extension), now I end up with

org.apache.maven.InternalErrorException: Internal error:
com.google.inject.ProvisionException: Unable to provision, see the
following errors:
1) No implementation for org.eclipse.aether.RepositorySystem was bound.

A whole bunch of stack trace but not a little info why the ***** it is
not happy. Now I need to add random "exportedArtifact" /
"exportedPackage" stuff to hope finding out where it has lost a
transitive dependency, also here absolutely no documentation what this
is supposed to do/work exactly beside some introduction that these xml
tags exits and reading the code... or probably add maven-compat
anywhere... or change provided to compile scope (even maven is jelling
at me that's bad and I will be punished soon)... not counting the many
times where I messed up the realms because I accidentally trying to use
XppDom objects in extensions and plugins and something between got
messed up.

With OSGi i get clear errors for missing requirements, I can clearly
share API (or declare I don't want to share it) and can reliable use it
without classlaoding problems.
If one wan't can even implement service filtering that would hide all
"illegal implemented API" ... and you can even make sure API is
(backward) compatible with implementation without waiting for a method
not found exception or alike.

Beside that I find it often more clear to distinguish between API (that
is only implemented by the framework) and SPI (that might be implemented
by extenders). So probably it would be good to have maven-api and
maven-spi (instead of "maven-core") to make this clear.

Am 16.11.22 um 14:53 schrieb Romain Manni-Bucau:
Hi,

Guess classrealm is fine for maven, it does not bring much issues (less
than OSGi or JPMS to be concrete), the real issue is the stability of
the
exposed API.
Thanks the hard work Guillaume did on that for maven 4 I guess it is
mainly
a matter of deciding what we do for maven 3.
Due to the resources and work needed I assume we can just play the
status-quo for maven 3.
Remaining question is for maven 4 do we drop the compatibilty. I don't
like
much the idea but a compat layer can solve that smoothly for maven >= 4
and
limit the work needed, no?

Romain Manni-Bucau
@rmannibucau <https://twitter.com/rmannibucau> |  Blog
<https://rmannibucau.metawerx.net/> | Old Blog
<http://rmannibucau.wordpress.com> | Github <
https://github.com/rmannibucau> |
LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book
<

https://www.packtpub.com/application-development/java-ee-8-high-performance



Le mer. 16 nov. 2022 à 13:00, Christoph Läubrich <m...@laeubi-soft.de>
a
écrit :

If you really like to separate API and get out of the ClassRealm-Hell
OSGi would be much more suitable:

https://issues.apache.org/jira/browse/MNG-7518

Am 16.11.22 um 12:30 schrieb Gary Gregory:
As much as I dislike JPMS, maybe Maven 4 should migrate to Java 9 or
11
and
adopt JPMS to better define its public APIs.

Gary

On Wed, Nov 16, 2022, 05:06 Tamás Cservenák <ta...@cservenak.net>
wrote:

Yes, to define rules is quite easy, but to make our users to obey
them
is
tricky :D

In general, I guess, we should. For this reason JapiCmp has been
used
in
Resolver since 1.9.0 (as noted on refd page end).

But while this was "kinda simple" to achieve in Resolver, I am
really
unsure if it is doable in Maven (sans 4 API) :(

Ultimately, this was the whole reason for API:
- users "grabbed" whatever could get hold on and used
- maven progress was really hindered by this, as that meant
modifying
(even
internal) interfaces without breaking clients was impossible, so we
went
with tricks, and more tricks and even more tricks that now pays
back.

The other day we had a question on ML about 4-alpha compatibility
breakage,
and from mail it was clear that the package of the referred class
was
having "internal" in it. I mean, developers should really take care
of
what
they import.

This is another huge plus for Takari lifecycle, it FORBIDS
compilation
against "encapsulated" internal classes....




http://takari.io/book/40-lifecycle.html#enforcing-dependency-usage-during-compilation

T

On Wed, Nov 16, 2022 at 10:44 AM Konrad Windszus <k...@apache.org>
wrote:

I guess this is the easy part, the tricky question remains: Do we
need
to
make sure that all Maven 3 API interfaces/classes stay 100%
backwards
compatible until we reach 4.100/5.0/whatever?

This wasn't handled consistently in master till now, e.g. the
classes
generated from




https://github.com/apache/maven/blob/master/maven-plugin-api/src/main/mdo/lifecycle.mdo
are now immutable, i.e. lack setter methods in Maven 4.
My change in




https://github.com/apache/maven/pull/827/files#diff-2324c8cead0ad922c829a8ca450764aa149d6efdfe7f841e64210f20efd148acR77
was not backwards compatible (removed a method on an interface
which
may
have been implemented by extensions...)

Konrad

On 2022/11/16 09:35:15 Tamás Cservenák wrote:
Unsure we want to deprecate all of Maven :)

But yes, in general, 3.x "Maven API" was "all that users can grab"
sadly,
and is probably our major source of problems and reason we started
Maven
4
API.

IMO, I'd consider them as "whole", and just say "starting with
Maven
4.100/5.0/whatever" the maven-core (any class out of it) is NOT
ACCESSIBLE
ANYMORE FROM PLUGINS.
And done.

Just as an example, here is what Maven Resolver has to say about
same
topic
(part of not-yet-released, vote is in process 1.9.1 version):





https://maven.apache.org/resolver-archives/resolver-LATEST/api-compatibility.html

HTH
T

On Wed, Nov 16, 2022 at 10:26 AM Konrad Windszus <k...@apache.org

wrote:

I see now there is already





https://github.com/apache/maven/blob/master/api/maven-api-meta/src/main/java/org/apache/maven/api/annotations/Provider.java
but to me the javadoc is not explicit enough. It should state:
Only
Maven
is allowed to implement/extend types with this annotation.

Konrad

On 2022/11/16 09:20:11 Konrad Windszus wrote:
Hi,
Unfortunately Maven 3 didn’t define a proper API. In effect
everything
somehow exposed through class loaders was considered API by
plugin/extension developers.
For Maven 4 a completely separate API was established in package
“org.apache.maven.api”, but what about the old packages used and
exported
in Maven 3?

For example in the context of
https://issues.apache.org/jira/browse/MNG-7588 <
https://issues.apache.org/jira/browse/MNG-7588> I want to evolve
the
package “org.apache.maven.plugin.descriptor”.
We already figured out that this particular package (although
not
part
of the Maven 4 API) is used from both Maven Core as well as Maven
Plugin
Tools, therefore this probably needs to stay backwards
compatible.
What about others like





https://github.com/apache/maven/blob/master/maven-core/src/main/java/org/apache/maven/plugin/MavenPluginManager.java
?
<





https://github.com/apache/maven/blob/master/maven-core/src/main/java/org/apache/maven/plugin/MavenPluginManager.java
?>
This interface should IMHO never been implemented outside Maven
Core
but
in fact it was exposed to all plugins/extensions (via





https://github.com/apache/maven/blob/a6b1ebb1cd40ca4b288fdeb30c6d2460323aa25b/maven-core/src/main/resources/META-INF/maven/extension.xml#L40
<





https://github.com/apache/maven/blob/a6b1ebb1cd40ca4b288fdeb30c6d2460323aa25b/maven-core/src/main/resources/META-INF/maven/extension.xml#L40
).

There are three options coming to my mind:

1. Deprecate the interfaces we don’t consider API and create new
ones
for Maven 4 which are not exported!
2. Modify the existing interfaces in a backwards compatible way
(but
somehow add a marker that they should not be implemented outside
core)
3. Modify the existing  interfaces in a backwards compatible way
(but
somehow add a marker that they should not be implemented outside
core)

For all three options we somehow need to come up with a list of
classes/interfaces currently being exported through the API class
loader,
which should be considered private and agree on an
Annotation/Javadoc
for
that (something like





https://github.com/mulesoft/api-annotations/blob/40b258afeff6560241dee5001ed00f1deb392e47/src/main/java/org/mule/api/annotation/NoImplement.java#L29
<





https://github.com/mulesoft/api-annotations/blob/40b258afeff6560241dee5001ed00f1deb392e47/src/main/java/org/mule/api/annotation/NoImplement.java#L29

or https://wiki.eclipse.org/API_Javadoc_tags#The_New_Solution <
https://wiki.eclipse.org/API_Javadoc_tags#The_New_Solution>

WDYT?

Konrad




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