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From sebb <seb...@gmail.com>
Subject Re: [VOTE] HttpComponents Core 4.2 release based on RC1
Date Tue, 24 Apr 2012 19:30:15 GMT
On 24 April 2012 19:33, Oleg Kalnichevski <olegk@apache.org> wrote:
> On Tue, 2012-04-24 at 19:03 +0100, sebb wrote:
>> On 24 April 2012 18:28, Oleg Kalnichevski <olegk@apache.org> wrote:
>> > On Tue, 2012-04-24 at 18:07 +0100, sebb wrote:
>> >> On 24 April 2012 17:18, Oleg Kalnichevski <olegk@apache.org> wrote:
>> >> > On Tue, 2012-04-24 at 16:59 +0100, sebb wrote:
>> >> >> On 24 April 2012 16:03, Oleg Kalnichevski <olegk@apache.org>
wrote:
>> >> >> > On Tue, 2012-04-24 at 15:18 +0100, sebb wrote:
>> >> >> >> On 24 April 2012 12:13, Oleg Kalnichevski <olegk@apache.org>
wrote:
>> >> >> >> > On Tue, 2012-04-24 at 02:48 +0100, sebb wrote:
>> >> >> >> >> On 23 April 2012 14:33, sebb <sebbaz@gmail.com>
wrote:
>> >> >> >> >> > On 21 April 2012 12:21, Oleg Kalnichevski
<olegk@apache.org> wrote:
>> >> >> >> >> >> Please vote on releasing these packages
as HttpComponents Core 4.2. The
>> >> >> >> >> >> vote is open for the at least 72 hours,
and only votes from
>> >> >> >> >> >> HttpComponents PMC members are binding.
The vote passes if at least
>> >> >> >> >> >> three binding +1 votes are cast and
there are more +1 than -1 votes.
>> >> >> >> >> >>
>> >> >> >> >> >> Packages:
>> >> >> >> >> >> http://people.apache.org/~olegk/httpcore-4.2-RC1/
>> >> >> >> >> >>
>> >> >> >> >> >> Release notes:
>> >> >> >> >> >> http://people.apache.org/~olegk/httpcore-4.2-RC1/RELEASE_NOTES.txt
>> >> >> >> >> >>
>> >> >> >> >> >> Maven artefacts:
>> >> >> >> >> >> https://repository.apache.org/content/repositories/orgapachehttpcomponents-078/org/apache/httpcomponents/
>> >> >> >> >> >>
>> >> >> >> >> >> SVN tag:
>> >> >> >> >> >> https://svn.apache.org/repos/asf/httpcomponents/httpcore/tags/4.2-RC1/
>> >> >> >> >> >>
>> >> >> >> >> >> --------------------------------------------------------------------------
>> >> >> >> >> >>  Vote:  HttpComponents Core 4.2 release
>> >> >> >> >> >>  [ ] +1 Release the packages as HttpComponents
Core 4.2.
>> >> >> >> >>
>> >> >> >> >> Sorry, I'm changing my vote:
>> >> >> >> >>
>> >> >> >> >> >>  [X] -1 I am against releasing the
packages (must include a reason).
>> >> >> >> >>
>> >> >> >> >> I've just noticed that Clirr reports several
compatibility issues against 4.1.
>> >> >> >> >>
>> >> >> >> >> I've not investigated in any detail, but it looks
as though at least
>> >> >> >> >> some of these are binary compatibility issues,
and they appear to be
>> >> >> >> >> in public APIs.
>> >> >> >> >>
>> >> >> >> >> It may be that these are not actually a problem,
but I think they need
>> >> >> >> >> to be investigated further.
>> >> >> >> >> If the errors are harmless - or perhaps only
affect source builds - it
>> >> >> >> >> would be helpful to update the site (and ideally
release notes)
>> >> >> >> >> accordingly.
>> >> >> >> >>
>> >> >> >> >> [No need to cancel the vote just yet, in case
I'm wrong.]
>> >> >> >> >>
>> >> >> >> >> BTW, we recently added test jars to the Commons
Maven output.
>> >> >> >> >> This should make it easier to run old tests against
new releases.
>> >> >> >> >>
>> >> >> >> >
>> >> >> >> > Sebastian
>> >> >> >> >
>> >> >> >> > The reported differences in public APIs reported
by Clirr are due to two
>> >> >> >> > things (1) upgrade from Java 1.3 to Java 1.5 (2)
removal of code
>> >> >> >> > deprecated between 4.0-beta1 and 4.0 (that is, before
4.0 GA, more than
>> >> >> >> > two years ago)
>> >> >> >> >
>> >> >> >> > We had a discussion about pros and cons of upgrading
to Java 1.5 and if
>> >> >> >> > I remember it correctly you were in favor of that
idea [1]. The changes
>> >> >> >> > have also been announced early enough (several releases
in advance) [2].
>> >> >> >> > They do make 4.1 and 4.2 not fully binary compatible
but I seriously
>> >> >> >> > doubt there will be a single user affected by incompatibility.
>> >> >> >> >
>> >> >> >> > I hope you will change your mind.
>> >> >> >>
>> >> >> >> I've been looking further at the changes.
>> >> >> >> The changes to NIO are all removals of deprecated methods,
so not a
>> >> >> >> problem (or at least, not our problem).
>> >> >> >>
>> >> >> >> The removed methods in HttpCore are also deprecated methods,
so not a problem.
>> >> >> >>
>> >> >> >
>> >> >> > Not only were they deprecated, they are deprecated two release
cycles
>> >> >> > back (before 4.0 official release).
>> >> >> >
>> >> >> >> Not sure why the value definitions of HTTP.DEFAULT_CONTENT_CHARSET
and
>> >> >> >> DEFAULT_PROTOCOL_CHARSET were changed.
>> >> >> >> Given that they are now deprecated, I would have thought
the values
>> >> >> >> could have been left untouched.
>> >> >> >
>> >> >> > I think the case changed (by mistake). I'll fix it right away.
>> >> >> >
>> >> >> >> However AFAICT that does not affect compatibility.
>> >> >> >>
>> >> >> >> [BTW, in future we ought to document in which release
items are deprecated]
>> >> >> >>
>> >> >> >> That just leaves the changed method signatures, which
are due to
>> >> >> >> adding generics to Iterator in o.a.h.message.Basic*Iterator
and to
>> >> >> >> AbstractMessageParser.
>> >> >> >> In the case of the MessageParser subclasses, these were
also changed
>> >> >> >> to use more specific subclasses:
>> >> >> >> HttpRequest and HttpResponse instead of their common super-interface
HttpMessage
>> >> >> >>
>> >> >> >> It's not obvious to me if these methods are likely to
be called by 3rd
>> >> >> >> party code or whether they are only likely to be used
internally.
>> >> >> >>
>> >> >> >
>> >> >> > You see, in any sane use case scenarios, especially as far
as iterators
>> >> >> > are concerned, the type returned from those methods would
always be cast
>> >> >> > to the expected subtype. In almost all cases regardless of
how those
>> >> >> > methods are being used the changes will have no effect at
the runtime
>> >> >> > behavior.
>> >> >>
>> >> >> The problem is that the return type of a method is part of the
signature.
>> >> >> Java won't find the method at runtime if the signature changes
between
>> >> >> compilation and run-time.
>> >> >>
>> >> >> This generally does not affect source compatibility, but it does
>> >> >> affect binary compat.
>> >> >>
>> >> >> We had this exact problem in Commons IO
>> >> >> We wanted to change a method return from void to something else;
>> >> >> however testing against pre-existing binaries showed that this
broke
>> >> >> binary compat.
>> >> >>
>> >> >
>> >> > All right. I'll revert those changes.
>> >>
>> >> We are already making the assumption breaking the API is OK for
>> >> long-deprecated methods, i.e. that user applications have migrated
>> >> away from the deprecated methods.
>> >>
>> >> So if the methods in question are not likely to be used by 3rd party
>> >> applications - are they effectively internal ? - we could consider
>> >> releasing with such breaks in compat, provided that such changes are
>> >> clearly documented.
>> >>
>> >
>> > It is almost as easy just to deprecate the affected classes.
>>
>> Which classes need to be deprecated?
>>
>> > What is done is done.
>>
>> Not sure I follow what you mean here.
>>
>
> I already reverted the changes that made 4.2 binary incompatible with
> 4.1 with exception of removal of deprecated code.
>
>> >> > I always thought the return type did not matter for binary method calls.
Obviously I was wrong.
>> >>
>> >> I originally thought the same. It was one of the long-time Commons
>> >> devs who pointed out the problem.
>> >>
>> >> It's particularly strange that changing void to non-void matters, but it
does.
>> >> [Perhaps it was easier than making an exception for that particular case]
>> >>
>> >
>> > I am not sure I understand the point of including the return type in the
>> > method signature since there will always be ambiguity in case there is
>> > no assignment of the method return to a variable.
>>
>> Not possible, see below.
>>
>> > int i = obj.dostuff(); // returns int
>> > double d = obj.dostuff(); // returns double
>>
>> That's not possible; obj.dostuff() can only have a single return type (or void).
>>
>> Compiler complains about a "duplicate method" otherwise.
>>
>
> Precisely. So, what is the point of including the return type in the
> method signature?

[I'm guessing here]

The compiler checks that the caller of an API method is using the
correct return type.
It's obviously important that the same type is provided at run-time.

If the return type were ignored by the loader when resolving method
references, the JVM would have to do additional run-time checks on the
return types.
This allows the error to be detected earlier (and it's cheaper).

>> > obj.dostuff(); // trouble
>> >
>> > That begs the question: what is the point of making things more complex
>> > than necessary.
>>
>> I don't think they did make things more complex.
>>
>
> See above.
>
>> > Anyway, as soon as you are happy with the content of the release notes,
>> > I'll cut another RC and call a vote.
>>
>> I've made some fixes to the parent pom, because unfortunately the
>> buildNumber plugin with javasvn implementation does not work with SVN
>> 1.7+ clients.
>>
>
> Yes, I am still on version 1.6.x
>
>> I assume you have not yet upgraded, because the "Implementation-Build"
>> headers are OK in the Manifests, so that can be fixed later.
>>
>
> Shall I go ahead and cut a new RC?

OK.

The remaining Clirr errors are for deprecated methods only, so I no
longer have objections on that score.

I see you have created new versions of the AbstractMessageParser
sub-classes, so the old ones can be kept and deprecated.
Solves the compat. problem without losing the type improvements. Excellent.

It would be great if there were a similar solution for the Iterator
classes that were reverted, but unfortunately that does not look
possible, and the classes might well have been used/extended by 3rd
parties. At least there are type-safe nextEntry() methods available
for use.

> Oleg
>
>
>
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