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From Stephan Ewen <se...@apache.org>
Subject Re: Scala 2.10/2.11 Maven dependencies
Date Mon, 02 Nov 2015 07:55:01 GMT
+1 for the approach discusses here, and for removing Scala dependencies
from modules that can be Scala independent.

It would be nice if pure Java users would not see any Scala versioning (on
flink-core, flink-java, later also flink-sreaming-java). I guess for any
runtime-related parts (including flink-client and currently all streaming
projects), we need the Scala versions...

On Sun, Nov 1, 2015 at 9:29 AM, Maximilian Michels <mxm@apache.org> wrote:

> Good point. Didn't know that. We can still add them for the release.
>
> On Sat, Oct 31, 2015 at 1:51 PM, Alexander Alexandrov
> <alexander.s.alexandrov@gmail.com> wrote:
> > My two cents - there are already Maven artifacts deployed for 2.11 in the
> > SNAPSHOT repository. I think it might be confusing if they suddenly
> > disappear for the stable release.
> >
> >
> > 2015-10-29 11:58 GMT+01:00 Maximilian Michels <mxm@apache.org>:
> >
> >> Seems like we agree that we need artifacts for different versions of
> Scala
> >> on Maven. There also seems to be a preference for including the version
> in
> >> the artifact name.
> >>
> >> I've created an issue and marked it to be resolved for 1.0. For the 0.10
> >> release, we will have binaries but no Maven artifacts. The biggest
> >> challenge I see is to remove Scala from as many modules as possible. For
> >> example, flink-java depends on Scala at the moment..
> >>
> >> https://issues.apache.org/jira/browse/FLINK-2940
> >>
> >> On Wed, Oct 28, 2015 at 7:31 PM, Frederick F. Kautz IV <
> fkautz@redhat.com>
> >> wrote:
> >>
> >> > No idea if I get a vote ;) Nevertheless, +1 to have binaries for both
> >> > versions in Maven and explicitly "scala versioned".
> >> >
> >> > Some background on this for those not as familiar with scala
> versioning:
> >> >
> >> > It's considered best practice to label what version of scala a library
> >> > uses in the artifact id.
> >> >
> >> > The reason is compiled scala code is only compatible with the major
> >> > version of scala it was compiled for. For example, a library
> compatible
> >> > with 2.10 is not compatible with 2.11. The same will be true with 2.12
> >> once
> >> > it is released. Mixing versions will result in undefined behavior
> which
> >> > will likely manifest itself as runtime exceptions.
> >> >
> >> > The convention to fix this problem is for all published libraries to
> >> > specify the version of scala they are compatible with. Leaving out the
> >> > scala version in a library is akin to saying "We don't depend on scala
> >> for
> >> > this library, so feel free to use whatever you want." Sbt users will
> >> > typically specify the version of scala they use and tooling is built
> >> around
> >> > ensuring consistency with the "%%" operator.
> >> >
> >> > E.g.
> >> >
> >> > scalaVersion := "2.11.4"
> >> >
> >> > // this resolves to to artifactID: "scalacheck_2.11"
> >> > libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.12.0" %
> >> "test"
> >> >
> >> > The most important part of this is that the scala version is explicit
> >> > which eliminates the problem for downstream users.
> >> >
> >> > Cheers,
> >> > Frederick
> >> >
> >> >
> >> > On 10/28/2015 10:55 AM, Fabian Hueske wrote:
> >> >
> >> >> +1 to have binaries for both versions in Maven and as build to
> download.
> >> >>
> >> >> 2015-10-26 17:11 GMT+01:00 Theodore Vasiloudis <
> >> >> theodoros.vasiloudis@gmail.com>:
> >> >>
> >> >> +1 for having binaries, I'm working on a Spark application currently
> >> with
> >> >>> Scala 2.11 and having to rebuild everything when deploying e.g.
to
> EC2
> >> >>> is a
> >> >>> pain.
> >> >>>
> >> >>> On Mon, Oct 26, 2015 at 4:22 PM, Ufuk Celebi <uce@apache.org>
> wrote:
> >> >>>
> >> >>> I agree with Till, but is this something you want to address in
this
> >> >>>> release already?
> >> >>>>
> >> >>>> I would postpone it to 1.0.0.
> >> >>>>
> >> >>>> – Ufuk
> >> >>>>
> >> >>>> On 26 Oct 2015, at 16:17, Till Rohrmann <trohrmann@apache.org>
> wrote:
> >> >>>>>
> >> >>>>> I would be in favor of deploying also Scala 2.11 artifacts
to
> Maven
> >> >>>>>
> >> >>>> since
> >> >>>
> >> >>>> more and more people will try out Flink with Scala 2.11. Having
the
> >> >>>>> dependencies in the Maven repository makes it considerably
easier
> for
> >> >>>>> people to get their Flink jobs running.
> >> >>>>>
> >> >>>>> Furthermore, I observed that people are not aware that
our
> deployed
> >> >>>>> artifacts, e.g. flink-runtime, are built with Scala 2.10.
As a
> >> >>>>>
> >> >>>> consequence,
> >> >>>>
> >> >>>>> they mix flink dependencies with other dependencies pulling
in
> Scala
> >> >>>>>
> >> >>>> 2.11
> >> >>>
> >> >>>> and then they wonder that the program crashes. It would be,
imho,
> >> >>>>>
> >> >>>> clearer
> >> >>>
> >> >>>> if all our dependencies which depend on a specific Scala version
> would
> >> >>>>>
> >> >>>> have
> >> >>>>
> >> >>>>> the corresponding Scala suffix appended.
> >> >>>>>
> >> >>>>> Adding the 2.10 suffix would also spare us the hassle of
upgrading
> >> to a
> >> >>>>> newer Scala version in the future, because then the artifacts
> >> wouldn't
> >> >>>>> share the same artifact name.
> >> >>>>>
> >> >>>>> Cheers,
> >> >>>>> Till
> >> >>>>>
> >> >>>>> On Mon, Oct 26, 2015 at 4:04 PM, Maximilian Michels <
> mxm@apache.org>
> >> >>>>>
> >> >>>> wrote:
> >> >>>>
> >> >>>>> Hi Flinksters,
> >> >>>>>>
> >> >>>>>> We have recently committed an easy way to change Flink's
Scala
> >> >>>>>>
> >> >>>>> version.
> >> >>>
> >> >>>> The
> >> >>>>
> >> >>>>> question arises now whether we should ship Scala 2.11 as
binaries
> and
> >> >>>>>>
> >> >>>>> via
> >> >>>>
> >> >>>>> Maven. For the rc0, I created all binaries twice, for Scala
2.10
> and
> >> >>>>>>
> >> >>>>> 2.11.
> >> >>>>
> >> >>>>> However, I didn't create Maven artifacts. This follows
our current
> >> >>>>>>
> >> >>>>> shipping
> >> >>>>
> >> >>>>> strategy where we only ship Hadoop1 and Hadoop 2.3.0 Maven
> >> >>>>>>
> >> >>>>> dependencies
> >> >>>
> >> >>>> but
> >> >>>>
> >> >>>>> additionally Hadoop 2.4, 2.6, 2.7 as binaries.
> >> >>>>>>
> >> >>>>>> Should we also upload Maven dependencies for Scala
2.11?
> >> >>>>>>
> >> >>>>>> If so, the next question arises: What version pattern
should we
> have
> >> >>>>>>
> >> >>>>> for
> >> >>>
> >> >>>> the Flink Scala 2.11 dependencies? For Hadoop, we append -hadoop1
> to
> >> >>>>>>
> >> >>>>> the
> >> >>>
> >> >>>> VERSION, e.g. artifactID=flink-core, version=0.9.1-hadoop1.
> >> >>>>>>
> >> >>>>>> However, it is common practice to append the suffix
to the
> >> artifactID
> >> >>>>>>
> >> >>>>> of
> >> >>>
> >> >>>> the Maven dependency, e.g. artifactID=flink-core_2.11,
> version=0.9.1.
> >> >>>>>>
> >> >>>>> This
> >> >>>>
> >> >>>>> has mostly historic reasons but is widely used.
> >> >>>>>>
> >> >>>>>> Whatever naming pattern we choose, it should be consistent.
I
> would
> >> be
> >> >>>>>>
> >> >>>>> in
> >> >>>>
> >> >>>>> favor of changing our artifact names to contain the Hadoop
and
> Scala
> >> >>>>>> version. This would also imply that all Scala dependent
Maven
> >> modules
> >> >>>>>> receive a Scala suffix (also the default Scala 2.10
modules).
> >> >>>>>>
> >> >>>>>> Cheers,
> >> >>>>>> Max
> >> >>>>>>
> >> >>>>>>
> >> >>>>
> >> >
> >>
>

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