Hi Yuriy, I agree, we can keep them separate. I just wanted to make you aware of it.
Thanks for the PR, it looks the way I expected. I just read over the KIP document again. I think it needs to be updated to the current proposal, and then we’ll be able to start the vote. Thanks, John On Tue, Jun 30, 2020, at 04:58, Yuriy Badalyantc wrote: > Hi everybody! > > Looks like a discussion about KIP-513 could take a while. I think we should > move forward with KIP-616 without waiting for KIP-513. > > I created a new pull request for KIP-616: > https://github.com/apache/kafka/pull/8955. It contains a new > `org.apache.kafka.streams.scala.serialization.Serdes` object without name > clash. An old one was marked as deprecated. This change is backward > compatible and it could be merged in any further release. > > On Wed, Jun 3, 2020 at 12:41 PM Yuriy Badalyantc <lmne...@gmail.com> wrote: > > > Hi, John > > > > Thanks for pointing that out. I expressed my thoughts about KIP-513 and > > its connection to KIP-616 in the KIP-513 mail list. > > > > - Yuriy > > > > On Sun, May 31, 2020 at 1:26 AM John Roesler <vvcep...@apache.org> wrote: > > > >> Hi Yuriy, > >> > >> I was just looking back at KIP-513, and I’m wondering if there’s any > >> overlap we should consider here, or if they are just orthogonal. > >> > >> Thanks, > >> -John > >> > >> On Thu, May 28, 2020, at 21:36, Yuriy Badalyantc wrote: > >> > At the current moment, I think John's plan is better than the original > >> plan > >> > described in the KIP. I think we should create a new `Serdes` in another > >> > package. The old one will be deprecated. > >> > > >> > - Yuriy > >> > > >> > On Fri, May 29, 2020 at 8:58 AM John Roesler <vvcep...@apache.org> > >> wrote: > >> > > >> > > Thanks, Matthias, > >> > > > >> > > If we go with the approach Yuriy and I agreed on, to deprecate and > >> replace > >> > > the whole class and not just a few of the methods, then the timeline > >> is > >> > > less of a concern. Under that plan, Yuriy can just write the new class > >> > > exactly the way he wants and people can cleanly swap over to the new > >> > > pattern when they are ready. > >> > > > >> > > The timeline was more significant if we were just going to deprecate > >> some > >> > > methods and add new methods to the existing class. That plan requires > >> two > >> > > implementation phases, where we first deprecate the existing methods > >> and > >> > > later swap the implicits at the same time we remove the deprecated > >> members. > >> > > Aside from the complexity of that approach, it’s not a breakage free > >> path, > >> > > as some users would be forced to continue using the deprecated members > >> > > until a future release drops them, breaking their source code, and > >> only > >> > > then can they update their code. > >> > > > >> > > That wouldn’t be the end of the world, and we’ve had to do the same > >> thing > >> > > in the past with the implicit conversations, but this is a much wider > >> > > scope, since it’s all the serdes. I’m happy with the new plan, since > >> it’s > >> > > not only one step, but also it provides everyone a breakage-free path. > >> > > > >> > > We can still consider dropping the deprecated class in 3.0; I just > >> wanted > >> > > to clarify how the timeline issue has changed. > >> > > > >> > > Thanks, > >> > > John > >> > > > >> > > On Thu, May 28, 2020, at 20:34, Matthias J. Sax wrote: > >> > > > I am not a Scale person, so I cannot really contribute much. > >> However for > >> > > > the deprecation period, if we get the change into 2.7, it might be > >> ok to > >> > > > remove the deprecated classed in 3.0. > >> > > > > >> > > > It would only be one minor release in between what is a little bit > >> short > >> > > > (we usually prefer at least two minor released, better three), but > >> if we > >> > > > have a good reason for it, it might be ok. > >> > > > > >> > > > If we cannot remove it in 3.0, it seems there would be a 4.0 in > >> about a > >> > > > year(?) when ZK removal is finished and we can remove the deprecated > >> > > > code than. > >> > > > > >> > > > > >> > > > -Matthias > >> > > > > >> > > > On 5/28/20 7:39 AM, John Roesler wrote: > >> > > > > Hi Yuriy, > >> > > > > > >> > > > > Sounds good to me! I had a feeling we were bringing different > >> context > >> > > > > to the discussion; thanks for sticking with the conversation > >> until we > >> > > got > >> > > > > it hashed out. > >> > > > > > >> > > > > I'm glad you prefer Serde*s*, since having multiple different > >> classes > >> > > with > >> > > > > the same name leads to all kinds of trouble. "Serdes" seems > >> relatively > >> > > > > safe because people in the Scala lib won't be using the Java > >> Serdes > >> > > class, > >> > > > > and they won't be using the deprecated and non-deprecated one at > >> the > >> > > > > same time. > >> > > > > > >> > > > > Thank again, > >> > > > > -John > >> > > > > > >> > > > > On Thu, May 28, 2020, at 02:21, Yuriy Badalyantc wrote: > >> > > > >> Ok, I understood you, John. I wasn't sure about kafka deprecation > >> > > policy > >> > > > >> and thought that the full cycle could be done with 2.7 version. > >> > > Waiting for > >> > > > >> 3.0 is too much, I agree with it. > >> > > > >> > >> > > > >> So, I think creating one more `Serdes` in another package is our > >> way. > >> > > I > >> > > > >> suggest one of the following: > >> > > > >> 1. `org.apache.kafka.streams.scala.serde.Serdes` > >> > > > >> 2. `org.apache.kafka.streams.scala.serialization.Serdes` > >> > > > >> > >> > > > >> About `Serde` vs `Serdes`. I'm strongly against `Serde` because > >> it > >> > > would > >> > > > >> lead to a new name clash with the > >> > > > >> `org.apache.kafka.common.serialization.Serde`. > >> > > > >> > >> > > > >> - Yuriy > >> > > > >> > >> > > > >> On Thu, May 28, 2020 at 11:12 AM John Roesler < > >> vvcep...@apache.org> > >> > > wrote: > >> > > > >> > >> > > > >>> Hi Yuriy, > >> > > > >>> > >> > > > >>> Thanks for the clarification. > >> > > > >>> > >> > > > >>> I guess my concern is twofold: > >> > > > >>> 1. We typically leave deprecated methods in place for at least a > >> > > major > >> > > > >>> release cycle before removing them, so it would seem abrupt to > >> have a > >> > > > >>> deprecation period of only one minor release. If we follow the > >> same > >> > > pattern > >> > > > >>> here, it would take over a year to finish this KIP. > >> > > > >>> 2. It doesn’t seem like there is a nonbreaking deprecation path > >> at > >> > > all if > >> > > > >>> people enumerate their imports (if they don’t use a wildcard). > >> In > >> > > that > >> > > > >>> case, they would have no path to implicitly use the newly named > >> > > serdes, and > >> > > > >>> therefore they would have no way to avoid continuing to use the > >> > > deprecated > >> > > > >>> ones. > >> > > > >>> > >> > > > >>> Since you mentioned that your reason is mainly the preference > >> for > >> > > the name > >> > > > >>> “Serde” or “Serdes”, can we explore just using one of those? > >> Would > >> > > it cause > >> > > > >>> some kind of conflict to use > >> org.apache.kafka.streams.scala.Serde or > >> > > to use > >> > > > >>> Serdes in a different package, like > >> > > > >>> org.apache.kafka.streams.scala.implicit.Serdes? > >> > > > >>> > >> > > > >>> I empathize with this desire. I faced the same dilemma when I > >> wanted > >> > > to > >> > > > >>> replace Processor but keep the class name in KIP-478. I wound up > >> > > creating a > >> > > > >>> new package for the new Processor. > >> > > > >>> > >> > > > >>> Thanks, > >> > > > >>> John > >> > > > >>> > >> > > > >>> On Wed, May 27, 2020, at 22:20, Yuriy Badalyantc wrote: > >> > > > >>>> Hi John, > >> > > > >>>> > >> > > > >>>> I'm stick with the `org.apache.kafka.streams.scala.Serdes` > >> because > >> > > it's > >> > > > >>>> sort of conventional in the scala community. If you have a > >> typeclass > >> > > > >>> `Foo`, > >> > > > >>>> you probably will search `Foo` related stuff in the `Foo` or > >> maybe > >> > > `Foos` > >> > > > >>>> (plural). All other places are far less discoverable for the > >> > > developers. > >> > > > >>>> > >> > > > >>>> I agree that the migration path is a bit complex for such > >> change. > >> > > But I > >> > > > >>>> think it's more important to provide good developer experience > >> than > >> > > to > >> > > > >>>> simplify migration. Also, I think it's debatable which > >> migration > >> > > path is > >> > > > >>>> better for library users. If we would create, for example, > >> > > `Serdes2`, > >> > > > >>>> library users will have to modify their code if they used any > >> part > >> > > of the > >> > > > >>>> old `Serde`. With my approach, most of the old code will still > >> work > >> > > > >>> without > >> > > > >>>> changes. Only explicit usage of implicits will need to be fixed > >> > > (because > >> > > > >>>> names will be changed, and old names will be deprecated). > >> Wildcard > >> > > > >>> imports > >> > > > >>>> will work without changes and will not lead to a name clash. > >> > > Moreover, > >> > > > >>> many > >> > > > >>>> users may not notice name clash problems. And with my migration > >> > > path, > >> > > > >>> they > >> > > > >>>> will not notice any changes at all. > >> > > > >>>> > >> > > > >>>> - Yuriy > >> > > > >>>> > >> > > > >>>> On Thu, May 28, 2020 at 7:48 AM John Roesler < > >> vvcep...@apache.org> > >> > > > >>> wrote: > >> > > > >>>> > >> > > > >>>>> Hi Yuriy, > >> > > > >>>>> > >> > > > >>>>> Thanks for the reply. I guess I've been out of the Scala game > >> for a > >> > > > >>>>> while; all this summoner business is totally new to me. > >> > > > >>>>> > >> > > > >>>>> I think I followed the rationale you provided, but I still > >> don't > >> > > see > >> > > > >>>>> why you can't implement your whole plan in a new class. What > >> > > > >>>>> is special about the existing Serdes class? > >> > > > >>>>> > >> > > > >>>>> Thanks, > >> > > > >>>>> -John > >> > > > >>>>> > >> > > > >>>>> On Tue, May 19, 2020, at 01:18, Yuriy Badalyantc wrote: > >> > > > >>>>>> Hi John, > >> > > > >>>>>> > >> > > > >>>>>> Your suggestion looks interesting. I think it's technically > >> > > doable. > >> > > > >>> But > >> > > > >>>>> I'm > >> > > > >>>>>> not sure that this is the better solution. I will try to > >> explain. > >> > > > >>> From > >> > > > >>>>> the > >> > > > >>>>>> scala developers' perspective, `Serde` looks really like a > >> > > typeclass. > >> > > > >>>>>> Typical typeclass in pure scala will look like this: > >> > > > >>>>>> > >> > > > >>>>>> ``` > >> > > > >>>>>> trait Serde[A] { > >> > > > >>>>>> def serialize(data: A): Array[Byte] > >> > > > >>>>>> def deserialize(data: Array[Byte]): A > >> > > > >>>>>> } > >> > > > >>>>>> object Serde extends DefaultSerdes { > >> > > > >>>>>> // "summoner" function. With this I can write `Serde[A]` > >> and > >> > > this > >> > > > >>> serde > >> > > > >>>>>> will be implicitly summonned. > >> > > > >>>>>> def apply[A](implicit ev: Serde[A]): Serde[A] = ev > >> > > > >>>>>> } > >> > > > >>>>>> > >> > > > >>>>>> trait DefaultSerdes { > >> > > > >>>>>> // default instances here > >> > > > >>>>>> } > >> > > > >>>>>> ``` > >> > > > >>>>>> > >> > > > >>>>>> Usage example (note, that there are no wildcards imports > >> here): > >> > > > >>>>>> ``` > >> > > > >>>>>> object Main extends App { > >> > > > >>>>>> import Serde // not wildcard import > >> > > > >>>>>> > >> > > > >>>>>> // explicit summonning: > >> > > > >>>>>> val stringSerde = Serde[String] // using summoner > >> > > > >>>>>> stringSerde.serialize(???) > >> > > > >>>>>> > >> > > > >>>>>> // implicit summonning > >> > > > >>>>>> def serialize[A: Serde](a: A) = { > >> > > > >>>>>> Serde[A].serialize(a) // summoner again > >> > > > >>>>>> } > >> > > > >>>>>> serialize("foo") > >> > > > >>>>>> } > >> > > > >>>>>> ``` > >> > > > >>>>>> > >> > > > >>>>>> Examples are pretty silly, but I just want to show common > >> > > patterns of > >> > > > >>>>>> working with typeclasses in scala. All default instances in > >> the > >> > > usage > >> > > > >>>>>> examples are found using implicits searching mechanism. Scala > >> > > > >>> compiler > >> > > > >>>>>> searches implicits in a lot of places. Including companion > >> > > objects. > >> > > > >>> In my > >> > > > >>>>>> examples compiler will found `Serde[String]` instance in the > >> > > > >>> companion > >> > > > >>>>>> object of `Serde` typeclass. > >> > > > >>>>>> > >> > > > >>>>>> Also, I want to pay attention to the summoner function. It > >> makes > >> > > > >>> usage of > >> > > > >>>>>> typeclasses very neat and clear. > >> > > > >>>>>> > >> > > > >>>>>> The example above was the example of the perfect solution > >> for the > >> > > > >>> scala > >> > > > >>>>>> developers. But this solution requires to create separate > >> `Serde` > >> > > > >>>>>> typeclass, to make all this implicit searching stuff works. I > >> > > don't > >> > > > >>> think > >> > > > >>>>>> that it worth it, because a lot of code should be > >> reimplemented > >> > > using > >> > > > >>>>> this > >> > > > >>>>>> new typeclass. But the main point of my example is to show > >> the > >> > > > >>> perfect > >> > > > >>>>>> solution. And I think we should strive to provide developer > >> > > > >>> experience > >> > > > >>>>>> close to this. > >> > > > >>>>>> > >> > > > >>>>>> It's a bit out of the scope of my KIP, but I have a plan to > >> make > >> > > > >>>>>> `org.apache.kafka.streams.scala.Serdes` more closer to the > >> > > solution > >> > > > >>>>> above. > >> > > > >>>>>> It could be done in 2 steps: > >> > > > >>>>>> 1. Fix implicit names. > >> > > > >>>>>> 2. Add summoner function. > >> > > > >>>>>> > >> > > > >>>>>> And with this scala developers will be able to write almost > >> the > >> > > same > >> > > > >>> code > >> > > > >>>>>> as in the example above: > >> > > > >>>>>> ``` > >> > > > >>>>>> object Main extends App { > >> > > > >>>>>> import org.apache.kafka.streams.scala.Serdes // not > >> wildcard > >> > > import > >> > > > >>>>>> > >> > > > >>>>>> val stringSerde = Serdes[String] > >> > > > >>>>>> stringSerde.serialize(???) > >> > > > >>>>>> > >> > > > >>>>>> def serialize[A: Serde](a: A) = { > >> > > > >>>>>> Serdes[A].serialize(a) > >> > > > >>>>>> } > >> > > > >>>>>> serialize("foo") > >> > > > >>>>>> } > >> > > > >>>>>> ``` > >> > > > >>>>>> Of course, wildcard import will still work. > >> > > > >>>>>> > >> > > > >>>>>> Other names will make this new entity (containing default > >> > > implicits) > >> > > > >>> less > >> > > > >>>>>> discoverable. And summoner usage, in this case, will look > >> weird: > >> > > > >>>>>> ``` > >> > > > >>>>>> object Main extends App { > >> > > > >>>>>> import org.apache.kafka.streams.scala.DefaultSerdes // not > >> > > wildcard > >> > > > >>>>> import > >> > > > >>>>>> > >> > > > >>>>>> val stringSerde = DefaultSerdes[String] > >> > > > >>>>>> stringSerde.serialize(???) > >> > > > >>>>>> > >> > > > >>>>>> def serialize[A: Serde](a: A) = { > >> > > > >>>>>> DefaultSerdes[A].serialize(a) > >> > > > >>>>>> } > >> > > > >>>>>> serialize("foo") > >> > > > >>>>>> } > >> > > > >>>>>> ``` > >> > > > >>>>>> > >> > > > >>>>>> So, I think it's more important to provide a solid and > >> familiar > >> > > > >>> developer > >> > > > >>>>>> experience for the scala developer. And renaming (or > >> creating a > >> > > new > >> > > > >>>>>> version) of `Serdes` will not help here. > >> > > > >>>>>> > >> > > > >>>>>> -Yuriy > >> > > > >>>>>> > >> > > > >>>>>> On Tue, May 19, 2020 at 11:56 AM John Roesler < > >> > > vvcep...@apache.org> > >> > > > >>>>> wrote: > >> > > > >>>>>> > >> > > > >>>>>>> Hi Yuriy, > >> > > > >>>>>>> > >> > > > >>>>>>> Thanks so much for the KIP! I didn’t anticipate the problem > >> you > >> > > > >>> laid > >> > > > >>>>> out > >> > > > >>>>>>> in the KIP, but I find it very plausible. > >> > > > >>>>>>> > >> > > > >>>>>>> Thanks for pushing back on the “convention” and raising the > >> > > issue, > >> > > > >>> and > >> > > > >>>>>>> also volunteering a solution! > >> > > > >>>>>>> > >> > > > >>>>>>> I’m wondering if we can “fix” it in one shot by just > >> deprecating > >> > > > >>> the > >> > > > >>>>> whole > >> > > > >>>>>>> Serdes class and replacing it with a new one containing the > >> defs > >> > > > >>> you > >> > > > >>>>>>> proposed. Then, people could just switch their import to > >> the new > >> > > > >>> one. > >> > > > >>>>>>> > >> > > > >>>>>>> Of course the new class needs to have a different name, > >> which is > >> > > > >>>>> always a > >> > > > >>>>>>> challenge in situations like this, so I might just throw out > >> > > > >>>>> ImplicitSerdes > >> > > > >>>>>>> as an option. > >> > > > >>>>>>> > >> > > > >>>>>>> Do you think this would work? > >> > > > >>>>>>> > >> > > > >>>>>>> Thanks again, > >> > > > >>>>>>> John > >> > > > >>>>>>> > >> > > > >>>>>>> On Mon, May 18, 2020, at 23:35, Yuriy Badalyantc wrote: > >> > > > >>>>>>>> Hi, > >> > > > >>>>>>>> > >> > > > >>>>>>>> I would like to propose KIP-616 to fix naming clash in the > >> kafka > >> > > > >>>>>>>> streams scala API: > >> > > > >>>>>>>> > >> > > > >>>>>>> > >> > > > >>>>> > >> > > > >>> > >> > > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-616%3A+Rename+implicit+Serdes+instances+in+kafka-streams-scala > >> > > > >>>>>>>> > >> > > > >>>>>>>> Looking forward to your feedback. > >> > > > >>>>>>>> > >> > > > >>>>>>>> -Yuriy > >> > > > >>>>>>>> > >> > > > >>>>>>> > >> > > > >>>>>> > >> > > > >>>>> > >> > > > >>>> > >> > > > >>> > >> > > > >> > >> > > > > >> > > > > >> > > > Attachments: > >> > > > * signature.asc > >> > > > >> > > >> > > >
