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From Andy Coates <a...@confluent.io>
Subject Re: [VOTE] KIP-476: Add Java AdminClient interface
Date Mon, 01 Jul 2019 11:22:27 GMT
Done. I've not deprecated the factory methods on the AdminClient for the
same reason the AdminClient itself is not deprecated, i.e. this would cause
unavoidable warnings for libraries / platforms that support multiple
versions of Kafka. However, I think we add a note to the Java docs of
`AdminClient` to indicate that its use, going forward, is discouraged in
favour of the new `Admin` interface and explain why its not  been
deprecated, but that it may/will be removed in a future version.

Regarding factory methods on interfaces: there seems to be some difference
of opinion here. I'm not sure of the best approach to revolve this. At the
moment the KIP has factory methods on the new `Admin` interface, rather
than some utility class. I prefer the utility class, but this isn't inline
with the patterns in the code base and some of the core team have expressed
they'd prefer to continue to have the factory methods on the interface.
I'm happy with this if others are.

Thanks,

Andy

On Thu, 27 Jun 2019 at 23:21, Matthias J. Sax <matthias@confluent.io> wrote:

> @Andy:
>
> What about the factory methods of `AdminClient` class? Should they be
> deprecated?
>
> One nit about the KIP: can you maybe insert "code blocks" to highlight
> the API changes? Code blocks would simplify to read the KIP a lot.
>
>
> -Matthias
>
> On 6/26/19 6:56 AM, Ryanne Dolan wrote:
> > +1 (non-binding)
> >
> > Thanks.
> > Ryanne
> >
> > On Tue, Jun 25, 2019 at 10:21 PM Satish Duggana <
> satish.duggana@gmail.com>
> > wrote:
> >
> >> +1 (non-binding)
> >>
> >> On Wed, Jun 26, 2019 at 8:37 AM Satish Duggana <
> satish.duggana@gmail.com>
> >> wrote:
> >>>
> >>> +1 Matthias/Andy.
> >>> IMHO, interface is about the contract, it should not have/expose any
> >>> implementation. I am fine with either way as it is more of taste or
> >>> preference.
> >>>
> >>> Agree with Ismael/Colin/Ryanne on not deprecating for good reasons.
> >>>
> >>>
> >>> On Mon, Jun 24, 2019 at 8:33 PM Andy Coates <andy@confluent.io> wrote:
> >>>>
> >>>> I agree Matthias.
> >>>>
> >>>> (In Scala, such factory methods are on a companion object. As Java
> >> doesn't
> >>>> have the concept of a companion object, an equivalent would be a
> >> utility
> >>>> class with a similar name...)
> >>>>
> >>>> However, I'll update the KIP to include the factory method on the
> >> interface.
> >>>>
> >>>> On Fri, 21 Jun 2019 at 23:40, Matthias J. Sax <matthias@confluent.io>
> >> wrote:
> >>>>
> >>>>> I still think, that an interface does not need to know anything
about
> >>>>> its implementation. But I am also fine if we add a factory method
to
> >> the
> >>>>> new interface if that is preferred by most people.
> >>>>>
> >>>>>
> >>>>> -Matthias
> >>>>>
> >>>>> On 6/21/19 7:10 AM, Ismael Juma wrote:
> >>>>>> This is even more reason not to deprecate immediately, there
is
> >> very
> >>>>> little
> >>>>>> maintenance cost for us. We should be mindful that many of our
> >> users (eg
> >>>>>> Spark, Flink, etc.) typically allow users to specify the kafka
> >> clients
> >>>>>> version and hence avoid using new classes/interfaces for some
> >> time. They
> >>>>>> would get a bunch of warnings they cannot do anything about
apart
> >> from
> >>>>>> suppressing.
> >>>>>>
> >>>>>> Ismael
> >>>>>>
> >>>>>> On Fri, Jun 21, 2019 at 4:00 AM Andy Coates <andy@confluent.io>
> >> wrote:
> >>>>>>
> >>>>>>> Hi Ismael,
> >>>>>>>
> >>>>>>> I’m happy enough to not deprecate the existing `AdminClient`
> >> class as
> >>>>> part
> >>>>>>> of this change.
> >>>>>>>
> >>>>>>> However, note that, the class will likely be empty, i.e.
all
> >> methods and
> >>>>>>> implementations will be inherited from the interface:
> >>>>>>>
> >>>>>>> public abstract class AdminClient implements Admin {
> >>>>>>> }
> >>>>>>>
> >>>>>>> Not marking it as deprecated has the benefit that users
won’t see
> >> any
> >>>>>>> deprecation warnings on the next release. Conversely, deprecating
> >> it
> >>>>> will
> >>>>>>> mean we can choose to remove this, now pointless class,
in the
> >> future
> >>>>> if we
> >>>>>>> choose.
> >>>>>>>
> >>>>>>> That’s my thinking for deprecation, but as I’ve said
I’m happy
> >> either
> >>>>> way.
> >>>>>>>
> >>>>>>> Andy
> >>>>>>>
> >>>>>>>> On 18 Jun 2019, at 16:09, Ismael Juma <ismael@juma.me.uk>
wrote:
> >>>>>>>>
> >>>>>>>> I agree with Ryanne, I think we should avoid deprecating
> >> AdminClient
> >>>>> and
> >>>>>>>> causing so much churn for users who don't actually care
about
> >> this
> >>>>> niche
> >>>>>>>> use case.
> >>>>>>>>
> >>>>>>>> Ismael
> >>>>>>>>
> >>>>>>>> On Tue, Jun 18, 2019 at 6:43 AM Andy Coates <andy@confluent.io>
> >> wrote:
> >>>>>>>>
> >>>>>>>>> Hi Ryanne,
> >>>>>>>>>
> >>>>>>>>> If we don't change the client code, then everywhere
will still
> >> expect
> >>>>>>>>> subclasses of `AdminClient`, so the interface will
be of no
> >> use, i.e.
> >>>>> I
> >>>>>>>>> can't write a class that implements the new interface
and pass
> >> it to
> >>>>> the
> >>>>>>>>> client code.
> >>>>>>>>>
> >>>>>>>>> Thanks,
> >>>>>>>>>
> >>>>>>>>> Andy
> >>>>>>>>>
> >>>>>>>>> On Mon, 17 Jun 2019 at 19:01, Ryanne Dolan <
> >> ryannedolan@gmail.com>
> >>>>>>> wrote:
> >>>>>>>>>
> >>>>>>>>>> Andy, while I agree that the new interface is
useful, I'm not
> >>>>> convinced
> >>>>>>>>>> adding an interface requires deprecating AdminClient
and
> >> changing so
> >>>>>>> much
> >>>>>>>>>> client code. Why not just add the Admin interface,
have
> >> AdminClient
> >>>>>>>>>> implement it, and have done?
> >>>>>>>>>>
> >>>>>>>>>> Ryanne
> >>>>>>>>>>
> >>>>>>>>>> On Mon, Jun 17, 2019 at 12:09 PM Andy Coates
<
> >> andy@confluent.io>
> >>>>>>> wrote:
> >>>>>>>>>>
> >>>>>>>>>>> Hi all,
> >>>>>>>>>>>
> >>>>>>>>>>> I think I've addressed all concerns. Let
me know if I've
> >> not.  Can I
> >>>>>>>>> call
> >>>>>>>>>>> another round of votes please?
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks,
> >>>>>>>>>>>
> >>>>>>>>>>> Andy
> >>>>>>>>>>>
> >>>>>>>>>>> On Fri, 14 Jun 2019 at 04:55, Satish Duggana
<
> >>>>>>> satish.duggana@gmail.com
> >>>>>>>>>>
> >>>>>>>>>>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>> Hi Andy,
> >>>>>>>>>>>> Thanks for the KIP. This is a good change
and it gives the
> >> user a
> >>>>>>>>>> better
> >>>>>>>>>>>> handle on Admin client usage. I agree
with the proposal
> >> except the
> >>>>>>>>> new
> >>>>>>>>>>>> `Admin` interface having all the methods
from `AdminClient`
> >>>>> abstract
> >>>>>>>>>>> class.
> >>>>>>>>>>>> It should be kept clean having only
the admin operations as
> >> methods
> >>>>>>>>>> from
> >>>>>>>>>>>> KafkaClient abstract class but not the
factory methods as
> >> mentioned
> >>>>>>>>> in
> >>>>>>>>>>> the
> >>>>>>>>>>>> earlier mail.
> >>>>>>>>>>>>
> >>>>>>>>>>>> I know about dynamic proxies(which were
widely used in
> >> RMI/EJB
> >>>>>>>>> world).
> >>>>>>>>>> I
> >>>>>>>>>>> am
> >>>>>>>>>>>> curious about the usecase using dynamic
proxies with Admin
> >> client
> >>>>>>>>>>>> interface. Dynamic proxy can have performance
penalty if it
> >> is used
> >>>>>>>>> in
> >>>>>>>>>>>> critical path. Is that the primary motivation
for creating
> >> the KIP?
> >>>>>>>>>>>>
> >>>>>>>>>>>> Thanks,
> >>>>>>>>>>>> Satish.
> >>>>>>>>>>>>
> >>>>>>>>>>>> On Wed, Jun 12, 2019 at 8:43 PM Andy
Coates <
> >> andy@confluent.io>
> >>>>>>>>> wrote:
> >>>>>>>>>>>>
> >>>>>>>>>>>>> I'm not married to that part.  That
was only done to keep
> >> it more
> >>>>>>>>> or
> >>>>>>>>>>> less
> >>>>>>>>>>>>> inline with what's already there,
(an abstract class that
> >> has a
> >>>>>>>>>> factory
> >>>>>>>>>>>>> method that returns a subclass....
sounds like the same
> >>>>>>>>> anti-pattern
> >>>>>>>>>>> ;))
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> An alternative would to have an
`AdminClients` utility
> >> class to
> >>>>>>>>>> create
> >>>>>>>>>>>> the
> >>>>>>>>>>>>> admin client.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> On Mon, 10 Jun 2019 at 19:31, Matthias
J. Sax <
> >>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>
> >>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> Hmmm...
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> So the new interface, returns
an instance of a class that
> >>>>>>>>>> implements
> >>>>>>>>>>>> the
> >>>>>>>>>>>>>> interface. This sounds a little
bit like an anti-pattern?
> >>>>>>>>> Shouldn't
> >>>>>>>>>>>>>> interfaces actually not know
anything about classes that
> >>>>>>>>> implement
> >>>>>>>>>>> the
> >>>>>>>>>>>>>> interface?
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> On 6/10/19 11:22 AM, Andy Coates
wrote:
> >>>>>>>>>>>>>>> `AdminClient` would be deprecated
purely because it would
> >> no
> >>>>>>>>>> longer
> >>>>>>>>>>>>> serve
> >>>>>>>>>>>>>>> any purpose and would be
virtually empty, getting all of
> >> its
> >>>>>>>>>>>>>> implementation
> >>>>>>>>>>>>>>> from the new interfar. It
would be nice to remove this
> >> from the
> >>>>>>>>>> API
> >>>>>>>>>>>> at
> >>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>> next major version bump,
hence the need to deprecate.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> `AdminClient.create()` would
return what it does today,
> >> (so
> >>>>>>>>> not a
> >>>>>>>>>>>>>> breaking
> >>>>>>>>>>>>>>> change).
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> On Tue, 4 Jun 2019 at 22:24,
Ryanne Dolan <
> >>>>>>>>> ryannedolan@gmail.com
> >>>>>>>>>>>
> >>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> The existing `AdminClient`
will be marked as deprecated.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> What's the reasoning
behind this? I'm fine with the other
> >>>>>>>>>> changes,
> >>>>>>>>>>>> but
> >>>>>>>>>>>>>>>> would prefer to keep
the existing public API intact if
> >> it's
> >>>>>>>>> not
> >>>>>>>>>>>>> hurting
> >>>>>>>>>>>>>>>> anything.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Also, what will AdminClient.create()
return? Would it be
> >> a
> >>>>>>>>>>> breaking
> >>>>>>>>>>>>>> change?
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Ryanne
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> On Tue, Jun 4, 2019,
11:17 AM Andy Coates <
> >> andy@confluent.io>
> >>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Hi folks
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> As there's been
no chatter on this KIP I'm assuming it's
> >>>>>>>>>>>>>> non-contentious,
> >>>>>>>>>>>>>>>>> (or just boring),
hence I'd like to call a vote for
> >> KIP-476:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>
> >>>>>>>
> >>>>>
> >>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-476%3A+Add+Java+AdminClient+Interface
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Thanks,
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Andy
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>
> >
>
>

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