modified README.md

README.md

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 # kafka-demo
+This project is just a sample demonstration inspired by question "How do
+we monitor a kafka stream with a OneAgent and see the data on Dynatrace?"
+
+# setup
+You need to [download](https://kafka.apache.org/downloads) kafka on your
+device. For this demo project the binary Scala 2.12 - kafka_2.12-3.5.1.tgz
+was downloaded, therefore kafka version 3.5.1 is used.
+
+# run
+First you have to start and run the zookeeper server, afterwards the kafka server
+and finally the consumers.
+```sh
+bin/zookeeper-server-start.sh config/zookeeper.properties
+bin/kafka-server-start.sh config/server.properties
+bin/kafka-console-consumer.sh --topic TOPIC_INSTANCE --from-beginning --bootstrap-server localhost:9092
+bin/kafka-console-consumer.sh --topic TOPIC_INSTANCE_JSON --from-beginning --bootstrap-server localhost:9092
+```
+`NOTE: MAKE SURE YOU FOLLOW THE ORDER!`
+
+Run this project by starting the KafkaDemoApplication!
+
+# demo
+Once everything is running open the following link in your browser:
+http://localhost:8080/api/v1/kafka/publish
+
+If you want to produce a message then you can add the message query parameter and
+your value as following:
+http://localhost:8080/api/v1/kafka/publish?message=Madrid
+http://localhost:8080/api/v1/kafka/publish?message=London
+http://localhost:8080/api/v1/kafka/publish?=Vienna
+http://localhost:8080/api/v1/kafka/publish?=Pizza
+
+On one of the consumers you will see the messages!
+
+It is possible to send a JSON Object. To do that you will have to send a POST
+request via e.g. Postman. In Postman choose the POST method and use this link:
+http://localhost:8080/api/v1/kafka/publish
+
+Afterward under Body, pick raw and instead Text pick JSON. In the body section
+you can add the following object:
+```JSON
+{
+    "id": 1,
+    "vin": "V09JHY4",
+    "location": "New York" 
+}
+```
+Send.
+
+You should be able to see the data in one of the consumers! If you encounter
+any warnings after starting the consumers you can ignore them!