Hi Florian,
I hope it's ok if I ask a few questions at this late stage...
Comment 1 ======
It seems like the proposal is to add a new "Named" interface that is
intended to be mixed in with the existing API objects at various points.
Just to preface some of my comments, it looks like your KIP was created
quite a while ago, so the API may have changed somewhat since you started.
As I see the API, there are a few different kinds of DSL method arguments:
* functions: things like Initializer, Aggregator, ValueJoiner,
ForEachAction... All of these are essentially Streams-flavored Function
interfaces with different arities, type bounds, and semantics.
* config objects: things like Produced, Consumed, Joined, Grouped... These
are containers for configurations, where the target of the configuration is
the operation itself
* raw configurations: things like a raw topic-name string and Materialized:
These are configurations for operations that have no config object, and for
various reasons, we didn't make one. The distinguishing feature is that the
target of the configuration is not the operation itself, but some aspect of
it. For example, in Materialized, we are not setting the caching behavior
of, for example, an aggregation; we're setting the caching behavior of a
materialized state store attached to the aggregation.
It seems like choosing to mix the Named interface in with the functions has
a couple of unfortunate side-effects:
* Aggregator is not the only function passed to any of the relevant
aggregate methods, so it seems a little arbitrary to pick that function
over Initializer or Merger.
* As you noted, branch() takes an array of Predicate, so we just ignore the
provided name(s), even though Predicate names are used elsewhere.
* Not all things that we want to name have function arguments, notably
source and sink, so we'd switch paradigms and use the config object instead.
* Adding an extra method to the function interfaces means that those are no
longer SAM interfaces. You proposed to add a default implementation, so we
could still pass a lambda if we don't want to set the name, but if we *do*
want to set the name, we can no longer use lambdas.
I think the obvious other choice would be to mix Named in with the config
objects instead, but this has one main downside of its own...
* not every operator we wish to name has a config object. I don't know if
everyone involved is comfortable with adding a config object to every
operator that's missing one.
Personally, I favor moving toward a more consistent state that's forward
compatible with any further changes we wish to make. I *think* that giving
every operator two forms (one with no config and one with a config object)
would be such an API.
Comment 2 =========
Finally, just a minor comment: the static method in Named wouldn't work
properly as defined. Assuming that we mix Named in with Produced, for
example, we'd need to be able to use it like:
> kStream.to("out", Produced.with("myOut"))
This doesn't work because with() returns a Named, but we need a Produced.
We can pull off a builder method in the interface, but not a static method.
To define a builder method in the interface that returns an instance of the
concrete subtype, you have to use the "curiously recurring generic" pattern.
It would look like:
public interface Named<N extends Named<N>> {
String name();
N withName(String name);
}
You can see where the name of the pattern comes from ;)
An implementation would then look like:
public class Produced implements Named<Produced> {
String name() { return name; }
Produced withName(final String name) { this.name = name; return this; }
}
Note that the generic parameter gets filled in properly in the implementing
class, so that you get the right return type out.
It doesn't work at all with a static factory method at the interface level,
so it would be up to Produced to define a static factory if it wants to
present one.
======
Those are my two feedbacks!
I hope you find this helpful, rather than frustrating. I'm sorry I didn't
get a chance to comment sooner.
Thanks for the KIP, I think it will be much nicer to be able to name the
processor nodes.
-John
On Tue, Nov 27, 2018 at 6:34 PM Guozhang Wang <wangg...@gmail.com> wrote:
> Hi Florian,
>
> I've made a pass over the PR. There are some comments that are related to
> the function names which may be affecting the KIP wiki page, but overall I
> think it looks good already.
>
>
> Guozhang
>
>
> On Fri, Nov 16, 2018 at 4:21 PM Guozhang Wang <wangg...@gmail.com> wrote:
>
> > Thanks Florian! I will take a look at the PR.
> >
> >
> >
> > On Mon, Nov 12, 2018 at 2:44 PM Florian Hussonnois <
> fhussonn...@gmail.com>
> > wrote:
> >
> >> Hi Matthias,
> >>
> >> Sorry I was absent for a while. I have started a new PR for this KIP. It
> >> is
> >> still in progress for now. I'm working on it.
> >> https://github.com/apache/kafka/pull/5909
> >>
> >> Le ven. 19 oct. 2018 à 20:13, Matthias J. Sax <matth...@confluent.io> a
> >> écrit :
> >>
> >> > What is the status of this KIP?
> >> >
> >> > -Matthias
> >> >
> >> > On 7/19/18 5:17 PM, Guozhang Wang wrote:
> >> > > Hello Florian,
> >> > >
> >> > > Sorry for being late... Found myself keep apologizing for late
> replies
> >> > > these days. But I do want to push this KIP's progress forward as I
> >> see it
> >> > > very important and helpful feature for extensibility.
> >> > >
> >> > > About the exceptions, I've gone through them and hopefully it is an
> >> > > exhaustive list:
> >> > >
> >> > > 1. KTable#toStream()
> >> > > 2. KStream#merge(KStream)
> >> > > 3. KStream#process() / transform() / transformValues()
> >> > > 4. KGroupedTable / KGroupedStream#count()
> >> > >
> >> > >
> >> > > Here's my reasoning:
> >> > >
> >> > > * It is okay not letting users to override the name for 1/2, since
> >> they
> >> > are
> >> > > too trivial to be useful for debugging, plus their processor names
> >> would
> >> > > not determine any related topic / store names.
> >> > > * For 3, I'd vote for adding overloaded functions with Named.
> >> > > * For 4, if users really want to name the processor she can call
> >> > > aggregate() instead, so I think it is okay to skip this case.
> >> > >
> >> > >
> >> > > Guozhang
> >> > >
> >> > >
> >> > >
> >> > > On Fri, Jul 6, 2018 at 3:06 PM, Florian Hussonnois <
> >> > fhussonn...@gmail.com>
> >> > > wrote:
> >> > >
> >> > >> Hi,
> >> > >>
> >> > >> The option #3 seems to be a good alternative and I find the API
> more
> >> > >> elegant (thanks John).
> >> > >>
> >> > >> But, we still have the need to overload some methods either because
> >> > they do
> >> > >> not accept an action instance or because they are translated to
> >> multiple
> >> > >> processors.
> >> > >>
> >> > >> For example, this is the case for methods branch() and merge(). We
> >> could
> >> > >> introduce a new interface Named (or maybe a different name ?) with
> a
> >> > method
> >> > >> name(). All action interfaces could extend this one to implement
> the
> >> > option
> >> > >> 3).
> >> > >> This would result by having the following overloads :
> >> > >>
> >> > >> Stream<K, V> merge(final Named name, final KStream<K, V> stream);
> >> > >> KStream<K, V>[] branch(final Named name, final Predicate<? super
> K, ?
> >> > super
> >> > >> V>... predicates)
> >> > >>
> >> > >> N.B : The list above is not exhaustive
> >> > >>
> >> > >> ---------
> >> > >> user's code will become :
> >> > >>
> >> > >> KStream<String, Integer> stream = builder.stream("test");
> >> > >> KStream<String, Integer>[] branches =
> >> > >> stream.branch(Named.with("BRANCH-STREAM-ON-VALUE"),
> >> > >> Predicate.named("STREAM-PAIR-VALUE", (k, v) -> v %
> 2
> >> ==
> >> > >> 0),
> >> > >> Predicate.named("STREAM-IMPAIR-VALUE", (k, v) -> v
> %
> >> 2
> >> > !=
> >> > >> 0));
> >> > >>
> >> > >> branches[0].to("pair");
> >> > >> branches[1].to("impair");
> >> > >> ---------
> >> > >>
> >> > >> This is a mix of the options 3) and 1)
> >> > >>
> >> > >> Le ven. 6 juil. 2018 à 22:58, Guozhang Wang <wangg...@gmail.com> a
> >> > écrit :
> >> > >>
> >> > >>> Hi folks, just to summarize the options we have so far:
> >> > >>>
> >> > >>> 1) Add a new "as" for KTable / KStream, plus adding new fields for
> >> > >>> operators-returns-void control objects (the current wiki's
> >> proposal).
> >> > >>>
> >> > >>> Pros: no more overloads.
> >> > >>> Cons: a bit departing with the current high-level API design of
> the
> >> > DSL,
> >> > >>> plus, the inconsistency between operators-returns-void and
> >> > >>> operators-not-return-voids.
> >> > >>>
> >> > >>> 2) Add overloaded functions for all operators, that accepts a new
> >> > control
> >> > >>> object "Described".
> >> > >>>
> >> > >>> Pros: consistent with current APIs.
> >> > >>> Cons: lots of overloaded functions to add.
> >> > >>>
> >> > >>> 3) Add another default function in the interface (thank you J8!)
> as
> >> > John
> >> > >>> proposed.
> >> > >>>
> >> > >>> Pros: no overloaded functions, no "Described".
> >> > >>> Cons: do we lose lambda functions really (seems not if we provide
> a
> >> > >> "named"
> >> > >>> for each func)? Plus "Described" may be more extensible than a
> >> single
> >> > >>> `String`.
> >> > >>>
> >> > >>>
> >> > >>> My principle of considering which one is better depends primarily
> on
> >> > "how
> >> > >>> to make advanced users easily use the additional API, while
> keeping
> >> it
> >> > >>> hidden from normal users who do not care at all". For that
> purpose I
> >> > >> think
> >> > >>> 3) > 1) > 2).
> >> > >>>
> >> > >>> One caveat though, is that changing the interface would not be
> >> > >>> binary-compatible though source-compatible, right? I.e. users need
> >> to
> >> > >>> recompile their code though no changes needed.
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>> Another note: for 3), if we really want to keep extensibility of
> >> > >> Described
> >> > >>> we could do sth. like:
> >> > >>>
> >> > >>> ---------
> >> > >>>
> >> > >>> public interface Predicate<K, V> {
> >> > >>> // existing method
> >> > >>> boolean test(final K key, final V value);
> >> > >>>
> >> > >>> // new default method adds the ability to name the predicate
> >> > >>> default Described described() {
> >> > >>> return new Described(null);
> >> > >>> }
> >> > >>> }
> >> > >>>
> >> > >>> ----------
> >> > >>>
> >> > >>> where user's code becomes:
> >> > >>>
> >> > >>> stream.filter(named("key", (k, v) -> true)); // note `named` now
> >> just
> >> > >>> sets a Described("key") in "described()".
> >> > >>>
> >> > >>> stream.filter(described(Described.as("key", /* any other fancy
> >> > >> parameters
> >> > >>> in the future*/), (k, v) -> true));
> >> > >>> ----------
> >> > >>>
> >> > >>>
> >> > >>> I feel it is not much likely that we'd need to extend it further
> in
> >> the
> >> > >>> future, so just a `String` would be good enough. But just listing
> >> all
> >> > >>> possibilities here.
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>> Guozhang
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>> On Fri, Jul 6, 2018 at 8:19 AM, John Roesler <j...@confluent.io>
> >> > wrote:
> >> > >>>
> >> > >>>> Hi Florian,
> >> > >>>>
> >> > >>>> Sorry I'm late to the party, but I missed the message originally.
> >> > >>>>
> >> > >>>> Regarding the names, it's probably a good idea to stick to the
> same
> >> > >>>> character set we're currently using: letters, numbers, and
> hyphens.
> >> > The
> >> > >>>> names are used in Kafka topics, files and folders, and RocksDB
> >> > >> databases,
> >> > >>>> and we also need them to work with the file systems of Windows,
> >> Linux,
> >> > >>> and
> >> > >>>> MacOS. My opinion is that with a situation like that, it's better
> >> to
> >> > be
> >> > >>>> conservative. It might also be a good idea to impose an upper
> >> limit on
> >> > >>> name
> >> > >>>> length to avoid running afoul of any of those systems.
> >> > >>>>
> >> > >>>> ---
> >> > >>>>
> >> > >>>> It seems like there's a small debate between 1) adding a new
> >> method to
> >> > >>>> KStream (and maybe KTable) to modify its name after the fact, or
> 2)
> >> > >>>> piggy-backing on the config objects where they exist and adding
> one
> >> > >> where
> >> > >>>> they don't. To me, #2 is the better alternative even though it
> >> > produces
> >> > >>>> more overloads and may be a bit awkward in places.
> >> > >>>>
> >> > >>>> The reason is simply that #1 is a high-level departure from the
> >> > >>>> graph-building paradigm we're using in the DSL. Consider:
> >> > >>>>
> >> > >>>> Graph.node1(config).node2(config)
> >> > >>>>
> >> > >>>> vs
> >> > >>>>
> >> > >>>> Graph.node1().config().node2().config()
> >> > >>>>
> >> > >>>> We could have done either, but we picked the former. I think it's
> >> > >>> probably
> >> > >>>> a good goal to try and stick to it so that developers can develop
> >> and
> >> > >>> rely
> >> > >>>> on their instincts for how the DSL will behave.
> >> > >>>>
> >> > >>>> I do want to present one alternative to adding new config
> objects:
> >> we
> >> > >> can
> >> > >>>> just add a "name()" method to all our "action" interfaces. For
> >> > example,
> >> > >>>> I'll demonstrate how we can add a "name" to Predicate and then
> use
> >> it
> >> > >> to
> >> > >>>> name a "KStream#filter" DSL operator:
> >> > >>>>
> >> > >>>> public interface Predicate<K, V> {
> >> > >>>> // existing method
> >> > >>>> boolean test(final K key, final V value);
> >> > >>>>
> >> > >>>> // new default method adds the ability to name the predicate
> >> > >>>> default String name() {
> >> > >>>> return null;
> >> > >>>> }
> >> > >>>>
> >> > >>>> // new static factory method adds the ability to wrap lambda
> >> > >>> predicates
> >> > >>>> with a named predicate
> >> > >>>> static <K, V> Predicate<K, V> named(final String name, final
> >> > >>>> Predicate<K, V> predicate) {
> >> > >>>> return new Predicate<K, V>() {
> >> > >>>> @Override
> >> > >>>> public boolean test(final K key, final V value) {
> >> > >>>> return predicate.test(key, value);
> >> > >>>> }
> >> > >>>>
> >> > >>>> @Override
> >> > >>>> public String name() {
> >> > >>>> return name;
> >> > >>>> }
> >> > >>>> };
> >> > >>>> }
> >> > >>>> }
> >> > >>>>
> >> > >>>> Then, here's how it would look to use it:
> >> > >>>>
> >> > >>>> // Anonymous predicates continue to work just fine
> >> > >>>> stream.filter((k, v) -> true);
> >> > >>>>
> >> > >>>> // Devs can swap in a Predicate that implements the name()
> method.
> >> > >>>> stream.filter(new Predicate<Object, Object>() {
> >> > >>>> @Override
> >> > >>>> public boolean test(final Object key, final Object value) {
> >> > >>>> return true;
> >> > >>>> }
> >> > >>>>
> >> > >>>> @Override
> >> > >>>> public String name() {
> >> > >>>> return "hey";
> >> > >>>> }
> >> > >>>> });
> >> > >>>>
> >> > >>>> // Or they can wrap their existing lambda using the static
> factory
> >> > >> method
> >> > >>>> stream.filter(named("key", (k, v) -> true));
> >> > >>>>
> >> > >>>> Just a thought.
> >> > >>>>
> >> > >>>> Overall, I think it's really valuable to be able to name the
> >> > >> processors,
> >> > >>>> for all the reasons you mentioned in the KIP. So thank you for
> >> > >>> introducing
> >> > >>>> this!
> >> > >>>>
> >> > >>>> Thanks,
> >> > >>>> -John
> >> > >>>>
> >> > >>>> On Thu, Jul 5, 2018 at 4:53 PM Florian Hussonnois <
> >> > >> fhussonn...@gmail.com
> >> > >>>>
> >> > >>>> wrote:
> >> > >>>>
> >> > >>>>> Hi, thank you very much for all you suggestions. I've started to
> >> > >> update
> >> > >>>> the
> >> > >>>>> KIP (
> >> > >>>>>
> >> > >>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-
> >> > >>>> 307%3A+Allow+to+define+custom+processor+names+with+KStreams+DSL
> >> > >>>>> ).
> >> > >>>>> Also, I propose to rename the Processed class into Described -
> >> this
> >> > >>> will
> >> > >>>> be
> >> > >>>>> more meaningful (but this is just a detail).
> >> > >>>>>
> >> > >>>>> I'm OK to not enforcing uppercase for specific names but should
> we
> >> > >>> allow
> >> > >>>>> arbitrary names with whitespaces for example ? Currently, I
> can't
> >> > >> tell
> >> > >>> if
> >> > >>>>> this can lead to some side effects ?
> >> > >>>>>
> >> > >>>>> Le lun. 11 juin 2018 à 01:31, Matthias J. Sax <
> >> matth...@confluent.io
> >> > >>>
> >> > >>> a
> >> > >>>>> écrit :
> >> > >>>>>
> >> > >>>>>> Just catching up on this thread.
> >> > >>>>>>
> >> > >>>>>> I like the general idea. Couple of comments:
> >> > >>>>>>
> >> > >>>>>> - I think that adding `Processed` (or maybe a different name?)
> >> is
> >> > >> a
> >> > >>>>>> valid proposal for stateless operators that only have a single
> >> > >>> overload
> >> > >>>>>> atm. It would align with the overall API design.
> >> > >>>>>>
> >> > >>>>>> - for all methods with multiple existing overloads, we can
> >> > >> consider
> >> > >>> to
> >> > >>>>>> extend `Consumed`, `Produced`, `Materialized` etc to take an
> >> > >>> additional
> >> > >>>>>> processor name (not sure atm how elegant this is; we would need
> >> to
> >> > >>>>>> "play" with the API a little bit; the advantage would be, that
> we
> >> > >> do
> >> > >>>> not
> >> > >>>>>> add more overloads what seems to be key for this KIP)
> >> > >>>>>>
> >> > >>>>>> - operators return void: while I agree that the "name first"
> >> > >>> chaining
> >> > >>>>>> idea is not very intuitive, it might still work, if we name the
> >> > >>> method
> >> > >>>>>> correctly (again, we would need to "play" with the API a little
> >> bit
> >> > >>> to
> >> > >>>>> see)
> >> > >>>>>>
> >> > >>>>>> - for DSL operators that are translated to multiple nodes: it
> >> > >> might
> >> > >>>>>> make sense to use the specified operator name as prefix and add
> >> > >>>>>> reasonable suffixes. For example, a join translates into 5
> >> > >> operators
> >> > >>>>>> that could be name "name-left-store-processor",
> >> > >>>>>> "name-left-join-processor", "name-right-store-processor",
> >> > >>>>>> "name-right-join-processor", and "name-join-merge-processor"
> (or
> >> > >>>>>> similar). Maybe just using numbers might also work.
> >> > >>>>>>
> >> > >>>>>> - I think, we should strip the number suffixes if a user
> >> provides
> >> > >>>> names
> >> > >>>>>>
> >> > >>>>>> - enforcing upper case seems to be tricky: for example, we do
> >> not
> >> > >>>>>> enforce upper case for store names and we cannot easily change
> it
> >> > >> as
> >> > >>> it
> >> > >>>>>> would break compatibility -- thus, for consistency reasons we
> >> might
> >> > >>> not
> >> > >>>>>> want to do this
> >> > >>>>>>
> >> > >>>>>> - for better understand of the impact of the KIP, it would be
> >> > >> quite
> >> > >>>>>> helpful if you would list all method names that are affected in
> >> the
> >> > >>> KIP
> >> > >>>>>> (ie, list all newly added overloads)
> >> > >>>>>>
> >> > >>>>>>
> >> > >>>>>> -Matthias
> >> > >>>>>>
> >> > >>>>>>
> >> > >>>>>> On 5/31/18 6:40 PM, Guozhang Wang wrote:
> >> > >>>>>>> Hi Florian,
> >> > >>>>>>>
> >> > >>>>>>> Re 1: I think changing the KStreamImpl / KTableImpl to allow
> >> > >>>> modifying
> >> > >>>>>> the
> >> > >>>>>>> processor name after the operator is fine as long as we do the
> >> > >>> check
> >> > >>>>>> again
> >> > >>>>>>> when modifying that. In fact, we are having some topology
> >> > >>>> optimization
> >> > >>>>>>> going on which may modify processor names in the final
> topology
> >> > >>>>> anyways (
> >> > >>>>>>> https://github.com/apache/kafka/pull/4983). Semantically I
> >> think
> >> > >>> it
> >> > >>>> is
> >> > >>>>>>> easier to understand to developers than "deciding the
> processor
> >> > >>> name
> >> > >>>>> for
> >> > >>>>>>> the next operator".
> >> > >>>>>>>
> >> > >>>>>>> Re 2: Yeah I'm thinking that for operators that translates to
> >> > >>>> multiple
> >> > >>>>>>> processor names, we can still use the provided "hint" to name
> >> the
> >> > >>>>>> processor
> >> > >>>>>>> names, e.g. for Joins we can name them as `join-foo-this` and
> >> > >>>>>>> `join-foo-that` etc if user calls `as("foo")`.
> >> > >>>>>>>
> >> > >>>>>>> Re 3: The motivation I had about removing the suffix is that
> it
> >> > >> has
> >> > >>>>> huge
> >> > >>>>>>> restrictions on topology compatibilities: consider if user
> code
> >> > >>>> added a
> >> > >>>>>> new
> >> > >>>>>>> operator, or library does some optimization to remove some
> >> > >>> operators,
> >> > >>>>> the
> >> > >>>>>>> suffix indexing may be changed for a large amount of the
> >> > >> processor
> >> > >>>>> names:
> >> > >>>>>>> this will in turn change the internal state store names, as
> well
> >> > >> as
> >> > >>>>>>> internal topic names as well, making the new application
> >> topology
> >> > >>> to
> >> > >>>> be
> >> > >>>>>>> incompatible with the ones. One rationale I had about this KIP
> >> is
> >> > >>>> that
> >> > >>>>>>> aligned this effort, moving forward we can allow users to
> >> > >> customize
> >> > >>>>>>> internal names so that they can still be reused even with
> >> > >> topology
> >> > >>>>>> changes
> >> > >>>>>>> (e.g. KIP-230), so I think removing the suffix index would be
> >> > >> more
> >> > >>>>>>> applicable in the long run.
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>> Guozhang
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>> On Thu, May 31, 2018 at 3:08 PM, Florian Hussonnois <
> >> > >>>>>> fhussonn...@gmail.com>
> >> > >>>>>>> wrote:
> >> > >>>>>>>
> >> > >>>>>>>> Hi ,
> >> > >>>>>>>> Thank you very much for your feedback.
> >> > >>>>>>>>
> >> > >>>>>>>> 1/
> >> > >>>>>>>> I agree that overloading most of the methods with a Processed
> >> is
> >> > >>> not
> >> > >>>>>> ideal.
> >> > >>>>>>>> I've started modifying the KStream API and I got to the same
> >> > >>>>> conclusion.
> >> > >>>>>>>> Also ading a new method directly to KStreamImpl and
> KTableImpl
> >> > >>>> classes
> >> > >>>>>>>> seems to be a better option.
> >> > >>>>>>>>
> >> > >>>>>>>> However a processor name cannot be redefined after calling an
> >> > >>>> operator
> >> > >>>>>> (or
> >> > >>>>>>>> maybe I miss something in the code).
> >> > >>>>>>>> From my understanding, this will only set the KStream name
> >> > >>> property
> >> > >>>>> not
> >> > >>>>>> the
> >> > >>>>>>>> processor name previsouly added to the topology builder -
> >> > >> leading
> >> > >>> to
> >> > >>>>>>>> InvalidTopology exception.
> >> > >>>>>>>>
> >> > >>>>>>>> So the new method should actually defines the name of the
> next
> >> > >>>>>> processor :
> >> > >>>>>>>> Below is an example :
> >> > >>>>>>>>
> >> > >>>>>>>> *stream.as <http://stream.as
> >> > >>>> (Processed.name("MAPPE_TO_UPPERCASE")*
> >> > >>>>>>>> * .map( (k, v) -> KeyValue.pair(k,
> v.toUpperCase()))*
> >> > >>>>>>>>
> >> > >>>>>>>> I think this approach could solve the cases for methods
> >> > >> returning
> >> > >>>>> void ?
> >> > >>>>>>>>
> >> > >>>>>>>> Regarding this new method we have two possible
> implementations
> >> :
> >> > >>>>>>>>
> >> > >>>>>>>> 1. Adding a method like : withName(String processorName)
> >> > >>>>>>>> 2. or adding a method accepting an Processed object :
> >> > >>>>> as(Processed).
> >> > >>>>>>>>
> >> > >>>>>>>> I think solution 2. is preferable as the Processed class
> could
> >> > >> be
> >> > >>>>>> enriched
> >> > >>>>>>>> further (in futur).
> >> > >>>>>>>>
> >> > >>>>>>>> 2/
> >> > >>>>>>>> As Guozhang said some operators add internal processors.
> >> > >>>>>>>> For example the branch() method create one KStreamBranch
> >> > >> processor
> >> > >>>> to
> >> > >>>>>> route
> >> > >>>>>>>> records and one KStreamPassThrough processor for each branch.
> >> > >>>>>>>> In that situation only the parent processor can be named. For
> >> > >>>> children
> >> > >>>>>>>> processors we could keep the current behaviour that add a
> >> suffix
> >> > >>>> (i.e
> >> > >>>>>>>> KSTREAM-BRANCHCHILD-)
> >> > >>>>>>>>
> >> > >>>>>>>> This also the case for the join() method that result to
> adding
> >> > >>>>> multiple
> >> > >>>>>>>> processors to the topology (windowing, left/right joins and a
> >> > >>> merge
> >> > >>>>>>>> processor).
> >> > >>>>>>>> I think, like for the branch method users could only define a
> >> > >>>>> processor
> >> > >>>>>>>> name prefix.
> >> > >>>>>>>>
> >> > >>>>>>>> 3/
> >> > >>>>>>>> I think we should still added a suffix like "-0000000000" to
> >> > >>>>> processor
> >> > >>>>>>>> name and enforce uppercases as this will keep some
> consistency
> >> > >>> with
> >> > >>>>> the
> >> > >>>>>>>> ones generated by the API.
> >> > >>>>>>>>
> >> > >>>>>>>> 4/
> >> > >>>>>>>> Yes, the KTable interface should be modified like KStream to
> >> > >> allow
> >> > >>>>>> custom
> >> > >>>>>>>> processor names definition.
> >> > >>>>>>>>
> >> > >>>>>>>> Thanks,
> >> > >>>>>>>>
> >> > >>>>>>>>
> >> > >>>>>>>> Le jeu. 31 mai 2018 à 19:18, Damian Guy <
> damian....@gmail.com>
> >> > >> a
> >> > >>>>> écrit
> >> > >>>>>> :
> >> > >>>>>>>>
> >> > >>>>>>>>> Hi Florian,
> >> > >>>>>>>>>
> >> > >>>>>>>>> Thanks for the KIP. What about KTable and other DSL
> >> interfaces?
> >> > >>>> Will
> >> > >>>>>> they
> >> > >>>>>>>>> not want to be able to do the same thing?
> >> > >>>>>>>>> It would be good to see a complete set of the public API
> >> > >> changes.
> >> > >>>>>>>>>
> >> > >>>>>>>>> Cheers,
> >> > >>>>>>>>> Damian
> >> > >>>>>>>>>
> >> > >>>>>>>>> On Wed, 30 May 2018 at 19:45 Guozhang Wang <
> >> wangg...@gmail.com
> >> > >>>
> >> > >>>>> wrote:
> >> > >>>>>>>>>
> >> > >>>>>>>>>> Hello Florian,
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> Thanks for the KIP. I have some meta feedbacks on the
> >> > >> proposal:
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> 1. You mentioned that this `Processed` object will be added
> >> > >> to a
> >> > >>>> new
> >> > >>>>>>>>>> overloaded variant of all the stateless operators, what
> about
> >> > >>> the
> >> > >>>>>>>>> stateful
> >> > >>>>>>>>>> operators? Would like to hear your opinions if you have
> >> > >> thought
> >> > >>>>> about
> >> > >>>>>>>>> that:
> >> > >>>>>>>>>> note for stateful operators they will usually be mapped to
> >> > >>>> multiple
> >> > >>>>>>>>>> processor node names, so we probably need to come up with
> >> some
> >> > >>>> ways
> >> > >>>>> to
> >> > >>>>>>>>>> define all their names.
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> 2. I share the same concern with Bill as for adding lots of
> >> > >> new
> >> > >>>>>>>> overload
> >> > >>>>>>>>>> functions into the stateless operators, as we have just
> spent
> >> > >>>> quite
> >> > >>>>>>>> some
> >> > >>>>>>>>>> effort in trimming them since 1.0.0 release. If the goal is
> >> to
> >> > >>>> just
> >> > >>>>>>>>> provide
> >> > >>>>>>>>>> some "hints" on the generated processor node names, not
> >> > >> strictly
> >> > >>>>>>>>> enforcing
> >> > >>>>>>>>>> the exact names that to be generated, then how about we
> just
> >> > >>> add a
> >> > >>>>> new
> >> > >>>>>>>>>> function to `KStream` and `KTable` classes like:
> >> > >>> "as(Processed)",
> >> > >>>>> with
> >> > >>>>>>>>> the
> >> > >>>>>>>>>> semantics as "the latest operators that generate this
> KStream
> >> > >> /
> >> > >>>>> KTable
> >> > >>>>>>>>> will
> >> > >>>>>>>>>> be named accordingly to this hint".
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> The only caveat, is that for all operators like
> `KStream#to`
> >> > >> and
> >> > >>>>>>>>>> `KStream#print` that returns void, this alternative would
> not
> >> > >>>> work.
> >> > >>>>>> But
> >> > >>>>>>>>> for
> >> > >>>>>>>>>> the current operators:
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> a. KStream#print,
> >> > >>>>>>>>>> b. KStream#foreach,
> >> > >>>>>>>>>> c. KStream#to,
> >> > >>>>>>>>>> d. KStream#process
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> I personally felt that except `KStream#process` users would
> >> > >> not
> >> > >>>>>> usually
> >> > >>>>>>>>>> bother to override their names, and for `KStream#process`
> we
> >> > >>> could
> >> > >>>>> add
> >> > >>>>>>>> an
> >> > >>>>>>>>>> overload variant with the additional Processed object.
> >> > >>>>>>>>>>
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> 3. In your example, the processor names are still added
> with
> >> a
> >> > >>>>> suffix
> >> > >>>>>>>>> like
> >> > >>>>>>>>>> "
> >> > >>>>>>>>>> -0000000000", is this intentional? If yes, why (I thought
> >> with
> >> > >>>> user
> >> > >>>>>>>>>> specified processor name hints we will not add suffix to
> >> > >>>> distinguish
> >> > >>>>>>>>>> different nodes of the same type any more)?
> >> > >>>>>>>>>>
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> Guozhang
> >> > >>>>>>>>>>
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> On Tue, May 29, 2018 at 6:47 AM, Bill Bejeck <
> >> > >> bbej...@gmail.com
> >> > >>>>
> >> > >>>>>>>> wrote:
> >> > >>>>>>>>>>
> >> > >>>>>>>>>>> Hi Florian,
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> Thanks for the KIP. I think being able to add more
> context
> >> > >> to
> >> > >>>> the
> >> > >>>>>>>>>>> processor names would be useful.
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> I like the idea of adding a "withProcessorName" to
> Produced,
> >> > >>>>> Consumed
> >> > >>>>>>>>> and
> >> > >>>>>>>>>>> Joined.
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> But instead of adding the "Processed" parameter to a large
> >> > >>>>> percentage
> >> > >>>>>>>>> of
> >> > >>>>>>>>>>> the methods, which would result in overloaded methods
> (which
> >> > >> we
> >> > >>>>>>>> removed
> >> > >>>>>>>>>>> quite a bit with KIP-182) what do you think of adding a
> >> > >> method
> >> > >>>>>>>>>>> to the AbstractStream class "withName(String
> >> processorName)"?
> >> > >>> BTW
> >> > >>>>> I"m
> >> > >>>>>>>>> not
> >> > >>>>>>>>>>> married to the method name, it's the best I can do off the
> >> > >> top
> >> > >>> of
> >> > >>>>> my
> >> > >>>>>>>>>> head.
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> For the methods that return void, we'd have to add a
> >> > >> parameter,
> >> > >>>> but
> >> > >>>>>>>>> that
> >> > >>>>>>>>>>> would at least cut down on the number of overloaded
> methods
> >> > >> in
> >> > >>>> the
> >> > >>>>>>>> API.
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> Just my 2 cents.
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> Thanks,
> >> > >>>>>>>>>>> Bill
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>> On Sun, May 27, 2018 at 4:13 PM, Florian Hussonnois <
> >> > >>>>>>>>>> fhussonn...@gmail.com
> >> > >>>>>>>>>>>>
> >> > >>>>>>>>>>> wrote:
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>>> Hi,
> >> > >>>>>>>>>>>>
> >> > >>>>>>>>>>>> I would like to start a new discussion on following KIP :
> >> > >>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-
> >> > >>>>>>>>>>>>
> >> > >>> 307%3A+Allow+to+define+custom+processor+names+with+KStreams+DSL
> >> > >>>>>>>>>>>>
> >> > >>>>>>>>>>>> This is still a draft.
> >> > >>>>>>>>>>>>
> >> > >>>>>>>>>>>> Looking forward for your feedback.
> >> > >>>>>>>>>>>> --
> >> > >>>>>>>>>>>> Florian HUSSONNOIS
> >> > >>>>>>>>>>>>
> >> > >>>>>>>>>>>
> >> > >>>>>>>>>>
> >> > >>>>>>>>>>
> >> > >>>>>>>>>>
> >> > >>>>>>>>>> --
> >> > >>>>>>>>>> -- Guozhang
> >> > >>>>>>>>>>
> >> > >>>>>>>>>
> >> > >>>>>>>>
> >> > >>>>>>>>
> >> > >>>>>>>> --
> >> > >>>>>>>> Florian HUSSONNOIS
> >> > >>>>>>>>
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>>
> >> > >>>>>>
> >> > >>>>>>
> >> > >>>>>
> >> > >>>>> --
> >> > >>>>> Florian HUSSONNOIS
> >> > >>>>>
> >> > >>>>
> >> > >>>
> >> > >>>
> >> > >>>
> >> > >>> --
> >> > >>> -- Guozhang
> >> > >>>
> >> > >>
> >> > >>
> >> > >> --
> >> > >> Florian HUSSONNOIS
> >> > >>
> >> > >
> >> > >
> >> > >
> >> >
> >> >
> >>
> >> --
> >> Florian HUSSONNOIS
> >>
> >
> >
> > --
> > -- Guozhang
> >
>
>
> --
> -- Guozhang
>
