Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #36583

Re: Jigsaw: RedHat and IBM say no

Show all headers | View raw

On 5/2/2017 4:45 PM, Silvio wrote:
> On 05/02/2017 10:18 PM, Arne Vajhøj wrote:
>> On 5/2/2017 3:42 PM, Silvio wrote:
>>>            If you have a large existing Java system that you are
>>> constantly improving and extending (which is very common in the standard
>>> software business) one might want to gradually introduce modules into
>>> the code-base while needing 100% backward compatibility for all existing
>>> code and configurations.
>>
>> Yes.
>>
>> And that should be possible.
>>
>> Let us say that you have 200 packages with 2000 classes.
>>
>> You build with Java 9 and it runs unchanged.
>
> Our most current system is written in Scala. Currently no Scala version
> runs on Java9.

Since Java 9 is not officially release yet, then that is not
wildly surprising.

But I would expect Scala to eventually support Java 9.

To quote them:

<quote>
We are planning to add (some) support for Java 9 in the near future. 
Full Java 9 support will be part of the 2.13 roadmap discussions.</quote>

http://www.scala-lang.org/news/2.12.0

And then that issue goes away.

So you may not go to Java 9 when it is released, but it will come.

 >>>                             Not knowing which of your legacy libraries
 >>> may fall apart and when that may happen is a much bigger problem.
 >>
 >> Why should they fall apart?
 >>
 >> Except by using SUN classes?
 >
 > Can I depend on my libraries not doing that? And if they do: what can I
 > do about it? Upgrading to newer versions can not be done without
 > extensive modifications.

Use of unsupported features can cause a lot of pain. Which is
why one should not use them.

And Jigsaw will prevent that from happening again by simply
not exporting those.

There will be some pain now due to old sins.

 > Both of our current applications fail on Java9. One because it is
 > written in Scala. The other one is pure Java but it fails at startup
 > with spurious class loading exceptions that are related to the use of an
 > ancient Asterisk library which we have not yet been able to fix.

But one of the problem will go away by itself. And the other
has its root cause in previous mistakes - Jigsaw is just
bringing them forward.

And I find it a bit hard to see the justification for your
claim that anything "Besides greenfield toy applications"
can not be slowly migrated to Java 9 with basis in:
* a Scala application
* "ancient Asterisk library" library

I will claim that there are lots of non toy applications not
suffering from those.

Of course it is frustrating for you, but I don't see it as
a general problem.

>> Then you take 1/10'th (10 packages with 200 classes) and convert
>> to a module. The rest of the application is unchanged - all
>> you need to change is the ref in the build and run to use the
>> new module.
>
> No. You did not read the article linked by the OP. If you depend on
> service loading introducing modules possibly breaks your application.

All the most common usages of ServiceLoader works.

There are a some corner cases that breaks.

Like assuming a specific order of the services returned.

Maybe they should try and improve compatibility in this area.

That is a bit more specific than just postponing Jigsaw
completely.

Arne

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Jigsaw: RedHat and IBM say no Chris Riesbeck <Chris.Riesbeck@gmail.com> - 2017-05-01 12:25 -0500
  Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 13:43 -0400
    Re: Jigsaw: RedHat and IBM say no Eric Douglas <e.d.programmer@gmail.com> - 2017-05-01 11:14 -0700
      Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 14:33 -0400
        Re: Jigsaw: RedHat and IBM say no Eric Douglas <e.d.programmer@gmail.com> - 2017-05-01 11:53 -0700
          Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 15:10 -0400
            Re: Jigsaw: RedHat and IBM say no Eric Douglas <e.d.programmer@gmail.com> - 2017-05-01 12:53 -0700
              Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 16:06 -0400
          Re: Jigsaw: RedHat and IBM say no Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-05-01 16:00 -0400
            Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 16:14 -0400
  Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 15:59 -0400
  Re: Jigsaw: RedHat and IBM say no Silvio <silvio@internet.com> - 2017-05-01 22:01 +0200
    Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 16:09 -0400
      Re: Jigsaw: RedHat and IBM say no Silvio <silvio@internet.com> - 2017-05-01 23:17 +0200
        Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-01 18:35 -0400
          Re: Jigsaw: RedHat and IBM say no Silvio <silvio@internet.com> - 2017-05-02 21:42 +0200
            Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-02 16:18 -0400
              Re: Jigsaw: RedHat and IBM say no Silvio <silvio@internet.com> - 2017-05-02 22:45 +0200
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-02 17:43 -0400
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-02 22:57 -0400
                Re: Jigsaw: RedHat and IBM say no lewbloch@gmail.com - 2017-05-10 12:42 -0700
                Re: Jigsaw: RedHat and IBM say no Eric Douglas <e.d.programmer@gmail.com> - 2017-05-10 13:12 -0700
                Re: Jigsaw: RedHat and IBM say no Silvio <silvio@internet.com> - 2017-05-10 23:25 +0200
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-14 20:44 -0400
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-15 19:27 -0400
                Re: Jigsaw: RedHat and IBM say no Sebastian <nowhere@nirvana.org> - 2017-05-16 22:39 +0200
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-16 20:48 -0400
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-07-21 19:45 -0400
              Re: Jigsaw: RedHat and IBM say no v_borchert@despammed.com (Volker Borchert) - 2017-05-02 23:09 +0000
                Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-02 22:45 -0400
  Re: Jigsaw: RedHat and IBM say no lewbloch@gmail.com - 2017-05-02 02:53 -0700
    Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-02 16:24 -0400
      Re: Jigsaw: RedHat and IBM say no Gene Wirchenko <genew@telus.net> - 2017-05-02 14:27 -0700
        Re: Jigsaw: RedHat and IBM say no Arne Vajhøj <arne@vajhoej.dk> - 2017-05-02 17:47 -0400

csiph-web