Thanks Guozhang for the comments .. we will start working on them .. regards.
On Mon, Mar 19, 2018 at 11:02 PM, Guozhang Wang <wangg...@gmail.com> wrote: > And one more comment about the type safety: > > 7. I'm in favor of the approach of enforcing type safety at compile time, > since with Scala's strong typing system I think it makes more sense to get > rid of config-based serde specifications that can cause runtime error in > the Scala wrapper. > > > Guozhang > > > On Mon, Mar 19, 2018 at 10:28 AM, Guozhang Wang <wangg...@gmail.com> > wrote: > > > Hello Debasish, > > > > Thanks for the KIP. Here are some comments: > > > > 1. About the naming: I'd also vote for option 2 and enforce users to > > rename when import since this scenario seems rare to me. > > > > 2. About the dependency: since this KIP can only be merged as early as > > 1.2, it means that for users who wants to use this artifact, say for > > version 1.2, she would need to bring in "kafka-streams" version 1.2. In > > addition, if we change the Java API in the future versions we'd also need > > to update the Scala wrapper at the same version as well, so in other > words > > "kafka-streams-scala" version X have to be with "kafka-streams" version X > > anyways. So I'd suggest we remove the version number in > "kafka-streams-scala > > only depends on the Scala standard library and Kafka Streams" as it may > > be confusing to readers. > > > > 3. For the KIP discussion, it need be based on the proposed state of this > > project in AK. More specifically, for the groupId in maven / gradle, it > > need to be "org.apache.kafka"; for the version, it need to be Kafka > release > > versions, e.g. 1.2.0. > > > > 4. In "New or Changed Public Interfaces" section, it does not mention the > > serde classes like "DefaultSerdes", but I think they should also be > > considered public APIs as users would most likely import these in her > > implementation. > > > > 5. Could you also list the changes you'd propose to made to build.gradle > > in kafka for adding this artifact? More details will help readers to > better > > understand your proposal. > > > > 6. I think it'd will be good to have a WordCount example code as part of > > this KIP, to illustrate how to code in this Scala wrapper, e.g. in > > o.a.k.scala.examples. But for this class we probably do not need to have > a > > separate artifact for it as we did in kafka-streams-examples. > > > > > > Guozhang > > > > > > On Mon, Mar 19, 2018 at 9:16 AM, Ted Yu <yuzhih...@gmail.com> wrote: > > > >> I agree with Sean on name unification. > >> > >> +1 to option 2. > >> > >> On Mon, Mar 19, 2018 at 7:23 AM, Sean Glover <sean.glo...@lightbend.com > > > >> wrote: > >> > >> > Type names: I vote for option 2. The user must explicitly add a > >> dependency > >> > to this library and the wrapper types are in a different package. It > >> seems > >> > reasonable to expect them to do an import rename if there's a need to > >> drop > >> > down to the Java API. > >> > > >> > Test Utils: The test utils in kafka-streams-scala are nice and lean, > but > >> > I'm not sure if it provides much more value than other options that > >> exist > >> > in the community. There's an embedded Kafka/ZK project implementation > >> for > >> > ScalaTest that's popular and active: manub/scalatest-embedded-kakfa. > >> It > >> > implies you must also use ScalaTest, which I acknowledge isn't > >> everyone's > >> > first choice for Scala test framework, but it probably is one of, if > not > >> > the most, popular library. It includes a DSL for Kafka Streams too. > If > >> > this KIP is accepted then perhaps a PR to that project could be made > to > >> > support the new wrapper implementations. > >> > > >> > https://github.com/manub/scalatest-embedded-kafka# > >> > scalatest-embedded-kafka-streams > >> > > >> > Sean > >> > > >> > On Sun, Mar 18, 2018 at 4:05 AM, Debasish Ghosh < > >> > debasish.gh...@lightbend.com> wrote: > >> > > >> > > > > >> > > > > Should this be 1.2 (maybe it's even better to not put any > >> version at > >> > > > all) > >> > > > >> > > > >> > > Actually wanted to emphasize that the support is from 1.0.0 onwards > .. > >> > > Should we make that explicit ? Like .. > >> > > > >> > > kafka-streams-scala only depends on the Scala standard library and > >> Kafka > >> > > > Streams 1.0.0+. > >> > > > >> > > > >> > > In 1.1 release, we add a new module `kafka-streams-test-utils` to > >> > simplify > >> > > > testing for Kafka Streams applications. Are those test utils > >> suitable > >> > for > >> > > > Scala users or should we add Scala wrappers for those, too? > >> > > > >> > > > >> > > I will check up and let you know .. > >> > > > >> > > Also I am not clear about the decision on renaming of Scala > >> abstractions. > >> > > Can we have a consensus on this ? Here's the summary .. > >> > > > >> > > *Option 1:* Keep names separate (KStream for Java class, KStreamS > for > >> > > Scala). No renaming of imports required. > >> > > *Option 2:* Unify names (KStream for Java and Scala class names). No > >> > > conflict since they will reside in different packages. But if we > need > >> to > >> > > use both abstractions, renaming of imports are required. But again, > >> this > >> > > may not be a too frequent use case. > >> > > > >> > > Suggestions ? > >> > > > >> > > regards. > >> > > > >> > > On Sat, Mar 17, 2018 at 3:07 AM, Matthias J. Sax < > >> matth...@confluent.io> > >> > > wrote: > >> > > > >> > > > Thanks a lot for the KIP! Two questions: > >> > > > > >> > > > 1) the KIP states: > >> > > > > >> > > > > kafka-streams-scala only depends on the Scala standard library > and > >> > > Kafka > >> > > > Streams 1.0.0. > >> > > > > >> > > > Should this be 1.2 (maybe it's even better to not put any version > >> at > >> > > all) > >> > > > > >> > > > > >> > > > 2) In 1.1 release, we add a new module `kafka-streams-test-utils` > to > >> > > > simplify testing for Kafka Streams applications. Are those test > >> utils > >> > > > suitable for Scala users or should we add Scala wrappers for > those, > >> > too? > >> > > > > >> > > > > >> > > > -Matthias > >> > > > > >> > > > > >> > > > On 3/16/18 11:10 AM, Ted Yu wrote: > >> > > > > Import renames seem to be fine. > >> > > > > > >> > > > > The class names with trailing 'S' look clean. > >> > > > > > >> > > > > Cheers > >> > > > > > >> > > > > On Fri, Mar 16, 2018 at 11:04 AM, Ismael Juma < > ism...@juma.me.uk> > >> > > wrote: > >> > > > > > >> > > > >> If this is rare (as it sounds), relying on import renames seems > >> fine > >> > > to > >> > > > me. > >> > > > >> Let's see what others think. > >> > > > >> > >> > > > >> Ismael > >> > > > >> > >> > > > >> On Fri, Mar 16, 2018 at 10:51 AM, Debasish Ghosh < > >> > > > >> debasish.gh...@lightbend.com> wrote: > >> > > > >> > >> > > > >>> I am not sure if this is practical or not. But theoretically a > >> user > >> > > may > >> > > > >>> want to extract the unsafe Java abstraction from the Scala > ones > >> and > >> > > use > >> > > > >>> Java APIs on them .. e.g. > >> > > > >>> > >> > > > >>> val userClicksStream: KStreamS[String, Long] = > >> > > > >>> builder.stream(userClicksTopic) // Scala abstraction > >> > > > >>> > >> > > > >>> val jStream: KStream[String, Long] = userClicksStream.inner // > >> > > > publishes > >> > > > >>> the underlying Java abstraction > >> > > > >>> > >> > > > >>> //.. work with Java, may be pass to some function written in > >> Java > >> > > > >>> > >> > > > >>> I do realize this is somewhat of a convoluted use case and may > >> not > >> > be > >> > > > >>> practically useful .. > >> > > > >>> > >> > > > >>> Otherwise we can very well work on the suggested approach of > >> > unifying > >> > > > the > >> > > > >>> names .. > >> > > > >>> > >> > > > >>> regards. > >> > > > >>> > >> > > > >>> > >> > > > >>> > >> > > > >>> On Fri, Mar 16, 2018 at 10:28 PM, Ismael Juma < > >> ism...@juma.me.uk> > >> > > > wrote: > >> > > > >>> > >> > > > >>>> What does "mixed mode application" mean? What are the cases > >> where > >> > a > >> > > > >> user > >> > > > >>>> would want to use both APIs? I think that would help > understand > >> > the > >> > > > >>>> reasoning. > >> > > > >>>> > >> > > > >>>> Thanks, > >> > > > >>>> Ismael > >> > > > >>>> > >> > > > >>>> On Fri, Mar 16, 2018 at 8:48 AM, Debasish Ghosh < > >> > > > >>>> debasish.gh...@lightbend.com> wrote: > >> > > > >>>> > >> > > > >>>>> Hi Damian - > >> > > > >>>>> > >> > > > >>>>> We could. But in case the user wants to use both Scala and > >> Java > >> > > APIs > >> > > > >>> (may > >> > > > >>>>> be for some mixed mode application), won't that be > confusing ? > >> > She > >> > > > >> will > >> > > > >>>>> have to do something like .. > >> > > > >>>>> > >> > > > >>>>> import o.a.k.s.scala.{KStream => KStreamS} > >> > > > >>>>> > >> > > > >>>>> to rename Scala imports or the other way round for imported > >> Java > >> > > > >>> classes. > >> > > > >>>>> > >> > > > >>>>> regards. > >> > > > >>>>> > >> > > > >>>>> > >> > > > >>>>> > >> > > > >>>>> On Fri, Mar 16, 2018 at 9:07 PM, Damian Guy < > >> > damian....@gmail.com> > >> > > > >>>> wrote: > >> > > > >>>>> > >> > > > >>>>>> Hi Debasish, > >> > > > >>>>>> > >> > > > >>>>>> Thanks for the KIP - will be a great addition to streams. > >> I've > >> > > only > >> > > > >>>> had a > >> > > > >>>>>> quick scan, but seeing as the Scala classes are going to be > >> in > >> > > > >> their > >> > > > >>>> own > >> > > > >>>>>> package could we drop the S at the end of the class names? > >> > > > >>>>>> > >> > > > >>>>>> Thanks, > >> > > > >>>>>> Damian > >> > > > >>>>>> > >> > > > >>>>>> > >> > > > >>>>>> On Fri, 16 Mar 2018 at 15:25 Debasish Ghosh < > >> > > > >>>>> debasish.gh...@lightbend.com> > >> > > > >>>>>> wrote: > >> > > > >>>>>> > >> > > > >>>>>>> Hi - > >> > > > >>>>>>> > >> > > > >>>>>>> A new KIP, KIP-270 is up for discussion: > >> > > > >>>>>>> > >> > > > >>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP- > >> > > > >>>>>> 270+-+A+Scala+Wrapper+Library+for+Kafka+Streams > >> > > > >>>>>>> > >> > > > >>>>>>> The relevant JIRA issue: https://issues.apache.org/ > >> > > > >>>>>> jira/browse/KAFKA-6670 > >> > > > >>>>>>> > >> > > > >>>>>>> The library as proposed in the KIP has been implemented at > >> > > > >>>>>>> https://github.com/lightbend/kafka-streams-scala and the > >> > current > >> > > > >>>>> release > >> > > > >>>>>>> is > >> > > > >>>>>>> 0.2.0 ( > >> > > > >>>>>>> https://github.com/lightbend/ > kafka-streams-scala/releases/ > >> > > > >>> tag/v0.2.0 > >> > > > >>>> ). > >> > > > >>>>>>> We at Lightbend has been using it since quite some time > now. > >> > > > >>>>>>> > >> > > > >>>>>>> regards. > >> > > > >>>>>>> > >> > > > >>>>>>> -- > >> > > > >>>>>>> Debasish Ghosh > >> > > > >>>>>>> Principal Engineer > >> > > > >>>>>>> > >> > > > >>>>>>> Twitter: @debasishg > >> > > > >>>>>>> Blog: http://debasishg.blogspot.com > >> > > > >>>>>>> Code: https://github.com/debasishg > >> > > > >>>>>>> > >> > > > >>>>>> > >> > > > >>>>> > >> > > > >>>>> > >> > > > >>>>> > >> > > > >>>>> -- > >> > > > >>>>> Debasish Ghosh > >> > > > >>>>> Principal Engineer > >> > > > >>>>> > >> > > > >>>>> Twitter: @debasishg > >> > > > >>>>> Blog: http://debasishg.blogspot.com > >> > > > >>>>> Code: https://github.com/debasishg > >> > > > >>>>> > >> > > > >>>> > >> > > > >>> > >> > > > >>> > >> > > > >>> > >> > > > >>> -- > >> > > > >>> Debasish Ghosh > >> > > > >>> Principal Engineer > >> > > > >>> > >> > > > >>> Twitter: @debasishg > >> > > > >>> Blog: http://debasishg.blogspot.com > >> > > > >>> Code: https://github.com/debasishg > >> > > > >>> > >> > > > >> > >> > > > > > >> > > > > >> > > > > >> > > > >> > > > >> > > -- > >> > > Debasish Ghosh > >> > > Principal Engineer > >> > > > >> > > Twitter: @debasishg > >> > > Blog: http://debasishg.blogspot.com > >> > > Code: https://github.com/debasishg > >> > > > >> > > >> > > >> > > >> > -- > >> > Senior Software Engineer, Lightbend, Inc. > >> > > >> > <http://lightbend.com> > >> > > >> > @seg1o <https://twitter.com/seg1o>, in/seanaglover > >> > <https://www.linkedin.com/in/seanaglover/> > >> > > >> > > > > > > > > -- > > -- Guozhang > > > > > > -- > -- Guozhang > -- Debasish Ghosh Principal Engineer Twitter: @debasishg Blog: http://debasishg.blogspot.com Code: https://github.com/debasishg
