Hi John. I updated the KIP. An old proposed implementation is now in the rejected alternatives.
- Yuriy On Sun, Jul 5, 2020 at 12:03 AM John Roesler <vvcep...@apache.org> wrote: > 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 > > >> > > > > >> > > > >> > > > > > >
