Hi Sachin,
1. You can run a remote query and we provide some example code
(https://www.confluent.io/blog/unifying-stream-processing-and-interactive-queries-in-apache-kafka/
<https://www.confluent.io/blog/unifying-stream-processing-and-interactive-queries-in-apache-kafka/>)
however by default APache Kafka ships with just the local query capabilities.
The above example has some code to do remote querying though.
2. So we don’t have a notion of windows closing in Kafka Streams. The
application will need to decide how frequently to query. So your Java
application can query, sleep, and query in a while(1) loop for example.
Cheers
Eno
> On Jul 15, 2017, at 7:07 AM, Sachin Mittal <sjmit...@gmail.com> wrote:
>
> Hi,
> I have created a simple window store to count occurrences of a given key.
>
>
> My pipeline is:
>
> TimeWindows windows = TimeWindows.of(n).advanceBy(n).until(30n);
> final StateStoreSupplier<WindowStore> supplier =
> Stores.create("key-table")
> .withKeys(Serdes.String())
> .withValues(Serdes.Long())
> .persistent()
> .enableLogging(topicConfigMap)
> .windowed(windows.size(), windows.maintainMs(),
> windows.segments, false)
> .build();
>
> builder.stream(Serdes.String(), valueSerde, "input-topic")
> .groupByKey()
> .count(windows, supplier)
>
>
> Now as per docs to query the store I would have to use:
>
> String storeName = supplier.name();
> ReadOnlyWindowStore<String,Long> localWindowStore =
> streams.store(storeName, QueryableStoreTypes.<String,
> Long>windowStore());
> String key = "some-key";
> long fromTime = ...;
> long toTime = ...;
> WindowStoreIterator<Long> countForWordsForWindows =
> localWindowStore.fetch(key, timeFrom, timeTo);
>
>
> My questions are:
>
> 1. Can I run a different java application to query the state store
> created by first application.
>
> If yes then how can I refer to the state store?
>
>
> 2. Value in the state store against any given key will keep
> incrementing as and when we read new data from the topic for a given
> time period.
>
> So at time t say count against k1 is 5 for a given window
>
> If we query that time we get 5, but at time t1 for same key and window
> count increases to 10.
>
> If we query that time we get 10.
>
> Question is how do we make sure that we query the state store only
> after it has aggregated all the values for a given window?
>
> And is there a way for that java application to run forever (just like
> streams application)to keep querying state store and report back the
> values.
>
>
> Thanks
>
> Sachin
