Nicolas,

here's some information I shared on StackOverflow (perhaps a bit outdated
by now, was back in Aug 2016) about how you can add a state store when
using KStreamBuilder: http://stackoverflow.com/a/39086805/1743580

-Michael




On Wed, Jan 18, 2017 at 5:18 PM, Nicolas Fouché <nfou...@onfocus.io> wrote:

> The reason I would not use `KStream.transform()` is that I want to call
> `ProcessorContext.forward()` several times, to different children. These
> children are sinks.
> My use case: I need to route my beacons to different topics. Right now, I
> use a series of `KStream.branch()` calls [1]. But would it be more
> "elegant" to be able to add 5 sinks to a topology, and forward my records
> to them in a custom processor ?
>
> Damian: About `TopologyBuilder.addProcessor(...)`, as far as I know, I
> have
> to give a parent processor. But the parent processor was generated by a
> high-level topologies. And names of processors created by `KStreamBuilder`
> are not accessible. (unless by inspecting the topology nodes I guess)
>
> [1] https://gist.github.com/nfo/c4936a24601352db23b18653a8ccc352
>
> Thanks.
> Nicolas
>
>
> 2017-01-18 15:56 GMT+01:00 Michael Noll <mich...@confluent.io>:
>
> > Nicolas,
> >
> > if I understand your question correctly you'd like to add further
> > operations after having called `KStream#process()`, which -- as you
> report
> > -- doesn't work because `process()` returns void.
> >
> > If that's indeed the case, +1 to Damian's suggest to use
> > `KStream.transform()` instead of `KStream.process()`.
> >
> > -Michael
> >
> >
> >
> >
> > On Wed, Jan 18, 2017 at 3:31 PM, Damian Guy <damian....@gmail.com>
> wrote:
> >
> > > You could possibly also use KStream.transform(...)
> > >
> > > On Wed, 18 Jan 2017 at 14:22 Damian Guy <damian....@gmail.com> wrote:
> > >
> > > > Hi Nicolas,
> > > >
> > > > Good question! I'm not sure why it is a terminal operation, maybe one
> > of
> > > > the original authors can chip in. However, you could probably work
> > around
> > > > it by using TopologyBuilder.addProcessor(...) rather then
> > > KStream.process
> > > >
> > > > Thanks,
> > > > Damian
> > > >
> > > > On Wed, 18 Jan 2017 at 13:48 Nicolas Fouché <nfou...@onfocus.io>
> > wrote:
> > > >
> > > > Hi,
> > > >
> > > > as far as I understand, calling `KStream.process` prevents the
> > developer
> > > > from adding further operations to a `KStreamBuilder` [1], because its
> > > > return type is `void`. Good.
> > > >
> > > > But it also prevents the developer from adding operations to its
> > > superclass
> > > > `TopologyBuilder`. In my case I wanted to add a sink, and the parent
> of
> > > > this sink would be the name of the Processor that is created by
> > > > `KStream.process`. Is there any reason why this method does not
> return
> > > the
> > > > processor name [2] ? Is it because it would be a bad idea continuing
> > > > building my topology with the low-level API ?
> > > >
> > > > [1]
> > > >
> > > > https://github.com/confluentinc/examples/blob/3.
> > > 1.x/kafka-streams/src/test/java/io/confluent/examples/streams/
> > > MixAndMatchLambdaIntegrationTest.java%23L56
> > > > [2]
> > > >
> > > > https://github.com/apache/kafka/blob/b6011918fbc36bfaa465bdcc750e24
> > > 35985d9101/streams/src/main/java/org/apache/kafka/streams/
> > > kstream/internals/KStreamImpl.java#L391
> > > >
> > > >
> > > > Thanks.
> > > > Nicolas.
> > > >
> > > >
> > >
> >
>

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