Enrico, It reminds me of the breaking changes in Guava and other widely used libraries. The problem for us is that we can never change our APIs if this is the case. Note that ListenerContainer has been marked deprecated since 4.1.1 (https://github.com/apache/curator/blob/apache-curator-4.1.1/curator-framework/src/main/java/org/apache/curator/framework/listen/ListenerContainer.java <https://github.com/apache/curator/blob/apache-curator-4.1.1/curator-framework/src/main/java/org/apache/curator/framework/listen/ListenerContainer.java>).
So, we're really left with these options: Release Curator 5.0 and let the issues fall onto those with compatibility problems Bundle or refer to a compatibility JAR that is put early in the CLASSPATH as I outlined in my test project Move Curator 5.0 to a new package so that it can exist in the same JVM as earlier versions of Curator. Backout the change and mark the APIs as deprecated and push the problem to a future version -Jordan > On May 24, 2020, at 3:58 PM, Enrico Olivelli <eolive...@gmail.com> wrote: > > > > Il Dom 24 Mag 2020, 22:48 Cameron McKenzie <cammcken...@apache.org > <mailto:cammcken...@apache.org>> ha scritto: > Enrico, > Can you explain your environment that exposes these backwards > compatibility issues? > > Cameron, > Let's say we have two libraries Foo and Bar that are compiled for Curator 4.x. > > I am now using in my Application Baz that use both Foo and Bar. So I have > Curator 4.x on the classpath. > Developers of Foo want to move to Curator 5.x in Foo 2.0, but Bar is still > happy with Curator 4.x. > > If I want to upgrade Foo to 2.0 I have these chances: > 1) Curator 5 is compatible with 4.x,so I can simply keep 5 and everything > works > 2) Curator 5 is not compatible with 4.x so I can't have both (this is current > case) > 3) Curator 5 is independent from 4.x and I can keep both of them > > The best option for users is 1). > > 3) is good anyway, but it needs more work for users that want to migrate. > > Option 2) is not good. Users will have to shade/relocate Curator 5 or 4 and > Foo 2.0 or Bar. > > Hope that this explains better the problem > Enrico > > > I am probably coming from a place of ignorance, but I > haven't seen new versions of a third party binary being dropped into an > existing environment without recompiling the application, so I have never > encountered these binary compatibility issues before. My expectation with > this release was that if you wanted to pickup the changes in Curator 5.0 > that you would rebuild your application against the new binaries and then > redeploy the application. Obviously this compilation will break if you are > using any of the changed APIs, but they are pretty trivial change to fix. > We could potentially deprecate the existing APIs and add the new ones, but > this will produce more tech debt to clean up later. > cheers > > On Sat, May 23, 2020 at 7:40 PM Enrico Olivelli <eolive...@gmail.com > <mailto:eolive...@gmail.com>> wrote: > > > I will check you trick ad soon as possible. I am sorry, this is a very > > busy week for me and do not have enough cycles. But I think that we should > > address this problem in order to ease the adoption of the new code and APIs. > > > > Did you evaluate to eventually rollback the breaking changes? > > > > Another alternative, if we want to let users use both the old and the new > > APIs is to simply rename all of the packages and start a brand new system. > > This approach was done in Apache Commons and IIRC it will be done with > > Netty5. We also did it with the new Apache Bookkeeper API. > > > > Pros: > > No need to preserve compatibility, we are free to clean up all of the tech > > debt. > > The switch to Curator 5 will be explicit opted in > > > > Cons: > > Cherry picks won't be straightforward. > > > > Enrico > > > > Il Ven 22 Mag 2020, 23:40 Jordan Zimmerman <jor...@jordanzimmerman.com > > <mailto:jor...@jordanzimmerman.com>> > > ha scritto: > > > >> Hi Everyone, > >> > >> I've coded a possible solution in the test project. See here: > >> > >> https://github.com/Randgalt/curator_5_0_test/blob/master/combo/pom.xml#L49 > >> <https://github.com/Randgalt/curator_5_0_test/blob/master/combo/pom.xml#L49> > >> > >> It uses the Maven dependency plugin to create a small compatibility JAR > >> that contains the Curator 4.3.0 versions of the classes that have changed > >> in 5.0.0 (i.e. the ones that no longer return ListenerContainer). If this > >> JAR is included in a CLASSPATH before Curator 5.0.0's JARs, these old > >> classes will take precedence and thus old binaries will continue to work. > >> The curator_5_0_test shows this. run.sh is the previous way with the > >> error. run-compatibility.sh is with the compatibility JAR. > >> > >> Thoughts? Notable, this doesn't change the master code of Curator at all. > >> We could add it to the 5.0 release. I don't think there's an issue with > >> this "hack". Can anyone think of one? I'd really appreciate people testing > >> with it. Try a build with just Curator 5.0 and then install and include > >> this curator-5_0-test:combo:1.0-SNAPSHOT early in the CLASSPATH - it should > >> work. > >> > >> -Jordan > >> > >> On May 21, 2020, at 10:43 AM, Jordan Zimmerman < > >> jor...@jordanzimmerman.com <mailto:jor...@jordanzimmerman.com>> wrote: > >> > >> Hello All, > >> > >> Sorry for the cross-posting but this is important enough to justify it. > >> > >> Apache Curator is in the process of releasing version 5.0. We've taken > >> the opportunity to address some long standing tech debt but this causes > >> breaking changes. We've detailed the breaks here: > >> http://curator.apache.org/staging/breaking-changes.html > >> <http://curator.apache.org/staging/breaking-changes.html>. The Clirr > >> report shows the exact API changes: > >> http://curator.apache.org/staging/curator-recipes/clirr-report.html > >> <http://curator.apache.org/staging/curator-recipes/clirr-report.html>. The > >> first two of these are the most worrisome. NodeCache's and > >> PathChildrenCache's getListenable() methods now have a different return > >> type. This has far reaching implications. If a Curator user were to drop in > >> Curator 5.0 without any code changes they will get runtime exceptions when > >> these methods are called. > >> > >> I've written a test that shows the problem: > >> > >> git clone https://github.com/Randgalt/curator_5_0_test.git > >> <https://github.com/Randgalt/curator_5_0_test.git> > >> cd curator_5_0_test > >> ./run.sh > >> > >> You will see: > >> > >> java.lang.NoSuchMethodError: > >> org.apache.curator.framework.recipes.cache.PathChildrenCache.getListenable()Lorg/apache/curator/framework/listen/ListenerContainer; > >> at binary.Curator50Test.run(Curator50Test.java:26) > >> at test.Test.main(Test.java:9) > >> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > >> at > >> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) > >> at > >> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > >> at java.lang.reflect.Method.invoke(Method.java:498) > >> at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297) > >> at java.lang.Thread.run(Thread.java:748) > >> > >> Enrico Olivelli brought this to our attention. Curator 5.0 is a major > >> version bump so breaking changes are implied. But, maybe this is blocker? > >> What do people think? If this is a serious enough concern we can come up > >> with a workaround. > >> > >> Please discuss and let's hold off completing the current release until > >> this has been fully discussed. > >> > >> -Jordan > >> > >> > >>
