Thank you Matthias, this is great feedback. Adding my comments below.
On Wed, 16 Feb 2022 at 00:42, Matthias J. Sax <mj...@apache.org> wrote: > Thanks for the KIP. > > In alignment to my reply to KIP-634, I am wondering if we are heading > into the right direction, or if we should consider to re-design the DSL > from scratch? > > I'm very excited about the idea of a DLS v2.0. It probably deserves its own thread to start discussing ideas. For this KIP specifically, I think about it as a continuation from KIP-478. Therefore, it could make sense to have it as part of the current version of the DSL. > > Even if we don't do a DSL 2.0 right now, I have some concerns about this > KIP: > > (1) I am not sure if the propose changed is backward compatible? We > currently have: > > void KStream#process(ProcessorSupplier, String...) > > The newly proposed method: > > KStream KStream#process(ProcessorSupplier) > > seems to be an incompatible change? > > The KIP states: > > > Modified method KStream#process should be compatible with previous > version, that at the moment is fixed to a Void return type. > > Why is it backward compatible? Having both old and new #process() seems > not to be compatible to me? Or are you proposing to _change_ the method > signature (if yes, the `String...` parameter to add a state store seems > to be missing)? For this case, it seems that existing programs would at > least need to be recompiled -- it would only be a source compatible > change, but not a binary compatible change? > > You're right. I'm not proposing the method signature. Totally agree about compatibility issue. I was only considering source compatibility and was ignorant that changing from void to a specific type would break binary compatibility. I will update the KIP to reflect this: > Modifications to method KStream#process are source compatible with previous version, though not binary compatible. Therefore will require users to recompile their applications with the latest version. > I am also wondering if/how this change related to KIP-401: > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=97553756 > > From a high level it might not conflict, but I wanted to double check? > > Wasn't aware of this KIP, thanks for sharing! I don't think there is conflict between KIPs, as far as I understand. > > For `KStream#processValues()`, my main concern is the added runtime > check if the key was modified or not -- it seems to provide bad user > experience -- enforcing that the key is not modified on an API level, > would seem to be much better. > > Last, what is the purpose of `setRecordKey()` and `clearRecordKey()`? I > am not sure if I understand their purpose? > > Both methods set/clear the context (current key) to be used when checking keys on forward(record) implementation. > enforcing that the key is not modified on an API level, would seem to be much better. Not sure if I understand how this would look like. Do you mean checking it on the Record itself or somewhere else? > -Matthias > > > On 2/15/22 11:53 AM, John Roesler wrote: > > My apologies, this feedback was intended for KIP-634. > > -John > > > > On Tue, Feb 15, 2022, at 13:15, John Roesler wrote: > >> Thanks for the update, Jorge, > >> > >> I've just looked over the KIP again. Just one more small > >> concern: > >> > >> 5) We can't just change the type of Record#headers() to a > >> new fully qualified type. That would be a source- > >> incompatible breaking change for users. > >> > >> Out options are: > >> * Deprecate the existing method and create a new one with > >> the new type > >> * If the existing Headers is "not great but ok", then maybe > >> we leave it alone. > >> > >> Thanks, > >> -John > >> > >> On Mon, 2022-02-14 at 13:58 -0600, Paul Whalen wrote: > >>> No specific comments, but I just wanted to mention I like the > direction of > >>> the KIP. My team is a big user of "transform" methods because of the > >>> ability to chain them, and I have always found the terminology > challenging > >>> to explain alongside "process". It felt like one concept with two > names. > >>> So moving towards a single API that is powerful enough to handle both > use > >>> cases seems absolutely correct to me. > >>> > >>> Paul > >>> > >>> On Mon, Feb 14, 2022 at 1:12 PM Jorge Esteban Quilcate Otoya < > >>> quilcate.jo...@gmail.com> wrote: > >>> > >>>> Got it. Thanks John, this make sense. > >>>> > >>>> I've updated the KIP to include the deprecation of: > >>>> > >>>> - KStream#transform > >>>> - KStream#transformValues > >>>> - KStream#flatTransform > >>>> - KStream#flatTransformValues > >>>> > >>>> > >>>> > >>>> On Fri, 11 Feb 2022 at 15:16, John Roesler <vvcep...@apache.org> > wrote: > >>>> > >>>>> Thanks, Jorge! > >>>>> > >>>>> I think it’ll be better to keep this KIP focused on KStream methods > only. > >>>>> I suspect that the KTable methods may be more complicated than just > that > >>>>> proposed replacement, but it’ll also be easier to consider that > question > >>>> in > >>>>> isolation. > >>>>> > >>>>> The nice thing about just deprecating the KStream methods and not the > >>>>> Transform* interfaces is that you can keep your proposal just scoped > to > >>>>> KStream and not have any consequences for the rest of the DSL. > >>>>> > >>>>> Thanks again, > >>>>> John > >>>>> > >>>>> On Fri, Feb 11, 2022, at 06:43, Jorge Esteban Quilcate Otoya wrote: > >>>>>> Thanks, John. > >>>>>> > >>>>>>> 4) I agree that we shouldn't deprecate the Transformer* > >>>>>> classes, but do you think we should deprecate the > >>>>>> KStream#transform* methods? I'm curious if there's any > >>>>>> remaining reason to have those methods, or if your KIP > >>>>>> completely obviates them. > >>>>>> > >>>>>> Good catch. > >>>>>> I considered that deprecating `Transformer*` and `transform*` would > go > >>>>> hand > >>>>>> in hand — maybe it happened similarly with old `Processor` and > >>>> `process`? > >>>>>> Though deprecating only `transform*` operations could be a better > >>>> signal > >>>>>> for users than non deprecating anything at all and pave the way to > it's > >>>>>> deprecation. > >>>>>> > >>>>>> Should this deprecation also consider including > >>>> `KTable#transformValues`? > >>>>>> The approach proposed on the KIP: > >>>>>> `ktable.toStream().processValues().toTable()` seems fair to me, > though > >>>> I > >>>>>> will have to test it further. > >>>>>> > >>>>>> I'm happy to update the KIP if there's some consensus around this. > >>>>>> Will add the deprecation notes these days and wait for any > additional > >>>>>> feedback on this topic before wrapping up the KIP. > >>>>>> > >>>>>> > >>>>>> On Fri, 11 Feb 2022 at 04:03, John Roesler <vvcep...@apache.org> > >>>> wrote: > >>>>>> > >>>>>>> Thanks for the update, Jorge! > >>>>>>> > >>>>>>> I just read over the KIP again, and I'm in support. One more > >>>>>>> question came up for me, though: > >>>>>>> > >>>>>>> 4) I agree that we shouldn't deprecate the Transformer* > >>>>>>> classes, but do you think we should deprecate the > >>>>>>> KStream#transform* methods? I'm curious if there's any > >>>>>>> remaining reason to have those methods, or if your KIP > >>>>>>> completely obviates them. > >>>>>>> > >>>>>>> Thanks, > >>>>>>> -John > >>>>>>> > >>>>>>> On Thu, 2022-02-10 at 21:32 +0000, Jorge Esteban Quilcate > >>>>>>> Otoya wrote: > >>>>>>>> Thank you both for your feedback! > >>>>>>>> > >>>>>>>> I have added the following note on punctuation: > >>>>>>>> > >>>>>>>> ``` > >>>>>>>> NOTE: The key validation can be defined when processing the > message. > >>>>>>>> Though, with punctuations it won't be possible to define the key > for > >>>>>>>> validation before forwarding, therefore it won't be possible to > >>>>> forward > >>>>>>>> from punctuation. > >>>>>>>> This is similar behavior to how `ValueTransformer`s behave at the > >>>>> moment. > >>>>>>>> ``` > >>>>>>>> > >>>>>>>> Also make it explicit also that we are going to apply referencial > >>>>>>> equality > >>>>>>>> for key validation. > >>>>>>>> > >>>>>>>> I hope this is covering all your feedback, let me know if I'm > >>>> missing > >>>>>>>> anything. > >>>>>>>> > >>>>>>>> Cheers, > >>>>>>>> Jorge. > >>>>>>>> > >>>>>>>> On Wed, 9 Feb 2022 at 22:19, Guozhang Wang <wangg...@gmail.com> > >>>>> wrote: > >>>>>>>> > >>>>>>>>> I'm +1 on John's point 3) for punctuations. > >>>>>>>>> > >>>>>>>>> And I think if people are on the same page that a reference > >>>> equality > >>>>>>> check > >>>>>>>>> per record is not a huge overhead, I think doing that enforcement > >>>> is > >>>>>>> better > >>>>>>>>> than documentations and hand-wavy undefined behaviors. > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> Guozhang > >>>>>>>>> > >>>>>>>>> On Wed, Feb 9, 2022 at 11:27 AM John Roesler < > vvcep...@apache.org > >>>>> > >>>>>>> wrote: > >>>>>>>>> > >>>>>>>>>> Thanks for the KIP Jorge, > >>>>>>>>>> > >>>>>>>>>> I'm in support of your proposal. > >>>>>>>>>> > >>>>>>>>>> 1) > >>>>>>>>>> I do agree with Guozhang's point (1). I think the cleanest > >>>>>>>>>> approach. I think it's cleaner and better to keep the > >>>>>>>>>> enforcement internal to the framework than to introduce a > >>>>>>>>>> public API or context wrapper for processors to use > >>>>>>>>>> explicitly. > >>>>>>>>>> > >>>>>>>>>> 2) I tend to agree with you on this one; I think the > >>>>>>>>>> equality check ought to be fast enough in practice. > >>>>>>>>>> > >>>>>>>>>> 3) I think this is implicit, but should be explicit in the > >>>>>>>>>> KIP: For the `processValues` API, because the framework sets > >>>>>>>>>> the key on the context before calling `process` and then > >>>>>>>>>> unsets it afterwards, there will always be no key set during > >>>>>>>>>> task puctuation. Therefore, while processors may still > >>>>>>>>>> register punctuators, they will not be able to forward > >>>>>>>>>> anything from them. > >>>>>>>>>> > >>>>>>>>>> This is functionally equivalent to the existing > >>>>>>>>>> transformers, by the way, that are also forbidden to forward > >>>>>>>>>> anything during punctuation. > >>>>>>>>>> > >>>>>>>>>> For what it's worth, I think this is the best tradeoff. > >>>>>>>>>> > >>>>>>>>>> The only alternative I see is not to place any restriction > >>>>>>>>>> on forwarded keys at all and just document that if users > >>>>>>>>>> don't maintain proper partitioning, they'll get undefined > >>>>>>>>>> behavior. That might be more powerful, but it's also a > >>>>>>>>>> usability problem. > >>>>>>>>>> > >>>>>>>>>> Thanks, > >>>>>>>>>> -John > >>>>>>>>>> > >>>>>>>>>> On Wed, 2022-02-09 at 11:34 +0000, Jorge Esteban Quilcate > >>>>>>>>>> Otoya wrote: > >>>>>>>>>>> Thanks Guozhang. > >>>>>>>>>>> > >>>>>>>>>>>> Does `ValueProcessorContext` have to be a public API? It > >>>> seems > >>>>>>> to me > >>>>>>>>>>> that this can be completely abstracted away from user > >>>> interfaces > >>>>>>> as an > >>>>>>>>>>> internal class > >>>>>>>>>>> > >>>>>>>>>>> Totally agree. No intention to add these as public APIs. Will > >>>>>>> update > >>>>>>>>> the > >>>>>>>>>>> KIP to reflect this. > >>>>>>>>>>> > >>>>>>>>>>>> in the past the rationale for enforcing it at the > >>>>>>>>>>> interface layer rather than do runtime checks is that it is > >>>> more > >>>>>>>>>> efficient. > >>>>>>>>>>>> I'm not sure how much overhead it may incur to check if the > >>>>> key > >>>>>>> did > >>>>>>>>> not > >>>>>>>>>>> change: if it is just a reference equality check maybe it's > >>>>> okay. > >>>>>>>>> What's > >>>>>>>>>>> your take on this? > >>>>>>>>>>> > >>>>>>>>>>> Agree, reference equality should cover this validation and the > >>>>>>> overhead > >>>>>>>>>>> impact should not be meaningful. > >>>>>>>>>>> Will update the KIP to reflect this as well. > >>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>> On Tue, 8 Feb 2022 at 19:05, Guozhang Wang < > >>>> wangg...@gmail.com> > >>>>>>> wrote: > >>>>>>>>>>> > >>>>>>>>>>>> Hello Jorge, > >>>>>>>>>>>> > >>>>>>>>>>>> Thanks for bringing this KIP! I think this is a nice idea to > >>>>>>> consider > >>>>>>>>>> using > >>>>>>>>>>>> a single overloaded function name for #process, just a > >>>> couple > >>>>>>> quick > >>>>>>>>>>>> questions after reading the proposal: > >>>>>>>>>>>> > >>>>>>>>>>>> 1) Does `ValueProcessorContext` have to be a public API? It > >>>>>>> seems to > >>>>>>>>> me > >>>>>>>>>>>> that this can be completely abstracted away from user > >>>>> interfaces > >>>>>>> as > >>>>>>>>> an > >>>>>>>>>>>> internal class, and we call the `setKey` before calling > >>>>>>>>>> user-instantiated > >>>>>>>>>>>> `process` function, and then in its overridden `forward` it > >>>>> can > >>>>>>> just > >>>>>>>>>> check > >>>>>>>>>>>> if the key changes or not. > >>>>>>>>>>>> 2) Related to 1) above, in the past the rationale for > >>>>> enforcing > >>>>>>> it at > >>>>>>>>>> the > >>>>>>>>>>>> interface layer rather than do runtime checks is that it is > >>>>> more > >>>>>>>>>> efficient. > >>>>>>>>>>>> I'm not sure how much overhead it may incur to check if the > >>>>> key > >>>>>>> did > >>>>>>>>> not > >>>>>>>>>>>> change: if it is just a reference equality check maybe it's > >>>>> okay. > >>>>>>>>>> What's > >>>>>>>>>>>> your take on this? > >>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> Guozhang > >>>>>>>>>>>> > >>>>>>>>>>>> On Tue, Feb 8, 2022 at 5:17 AM Jorge Esteban Quilcate Otoya > >>>> < > >>>>>>>>>>>> quilcate.jo...@gmail.com> wrote: > >>>>>>>>>>>> > >>>>>>>>>>>>> Hi Dev team, > >>>>>>>>>>>>> > >>>>>>>>>>>>> I'd like to start a new discussion thread on Kafka Streams > >>>>>>> KIP-820: > >>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>> > >>>>>>> > >>>>> > >>>> > https://cwiki.apache.org/confluence/display/KAFKA/KIP-820%3A+Extend+KStream+process+with+new+Processor+API > >>>>>>>>>>>>> > >>>>>>>>>>>>> This KIP is aimed to extend the current `KStream#process` > >>>>> API > >>>>>>> to > >>>>>>>>>> return > >>>>>>>>>>>>> output values that could be chained across the topology, > >>>> as > >>>>>>> well as > >>>>>>>>>>>>> introducing a new `KStream#processValues` to use processor > >>>>>>> while > >>>>>>>>>>>> validating > >>>>>>>>>>>>> keys haven't change and repartition is not required. > >>>>>>>>>>>>> > >>>>>>>>>>>>> Looking forward to your feedback. > >>>>>>>>>>>>> > >>>>>>>>>>>>> Regards, > >>>>>>>>>>>>> Jorge. > >>>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> -- > >>>>>>>>>>>> -- Guozhang > >>>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>> > >>>>>>>>> -- > >>>>>>>>> -- Guozhang > >>>>>>>>> > >>>>>>> > >>>>>>> > >>>>> > >>>> >
