== What is this app?

This is an example of a Spring Cloud Stream processor using Kafka Streams support.

The example is based on a contrived use case of tracking products by interactively querying their status.
The program accepts product ID's and track their counts hitherto by interactively querying the underlying store. \
This sample uses lambda expressions and thus requires Java 8+.

=== Running the app:

Go to the root of the repository and do:

`docker-compose up -d`

`./mvnw clean package`

`java -jar target/kafka-streams-interactive-query-basic-0.0.1-SNAPSHOT.jar --app.product.tracker.productIds=123,124,125`

The above command will track products with ID's 123,124 and 125 and print their counts seen so far every 30 seconds.

Issue the following commands:

`docker exec -it kafka-iq-basic /opt/kafka/bin/kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic products`

Enter the following in the console producer (one line at a time) and watch the output on the console (or IDE) where the application is running.

```
{"id":"123"}
{"id":"124"}
{"id":"125"}
{"id":"123"}
{"id":"123"}
{"id":"123"}
```