modify intro

Author: knonomura

README.md

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 GridDB Sample Application for Apache Kafka
 
 # Project Overview
-This sample application provides an introduction on how to use GridDB with Kafka. The main idea is to connect a GridDB database to a Kafka cluster so that messages or records received from a Kafka cluster can be received, processed, and eventually stored into GridDB. This project also uses MQTT server (ex. Mosquitto) to receive and send messages. In this application, the MQTT messages represent sensor data being sent to the Kafka cluster to be stored in GridDB. The purpose and advantage of using these messaging brokers is that they allow different programs and processes to communicate and send data to each other.
+This sample application provides an introduction on how to use GridDB with [Apache Kafka](https://kafka.apache.org/). The main idea is to connect a GridDB database to a Kafka cluster so that messages or records received from a Kafka cluster can be received, processed, and eventually stored into GridDB. This project also uses MQTT server (ex. Mosquitto) to receive and send messages. In this application, the MQTT messages represent sensor data being sent to the Kafka cluster to be stored in GridDB. The purpose and advantage of using these messaging brokers is that they allow different programs and processes to communicate and send data to each other.
 
 For this application, an MQTT client program generates random data which can be used to represent sensor readings in a real-world Internet of Things (IoT) system; some examples are volt readings from an electricity sensor or light readings from a light sensor. The MQTT library is used to publish this data to a machine's local MQTT server and from there a MQTT-Kafka connector passes that data to the Kafka cluster where a GridDBSinkConnector and GridDBSinkTask will read and parse that record into a GridDB row to be inserted into a container. A client app that uses the MQTT API will publish APIs that will be received by the MQTT server, which then publishes it to listening MQTT subscribers. The Kafka Source connector is a MQTT subscriber, and publishes the message to a Kafka server. Kafka then publishes the message to its subscribers, one of which is the GridDB Sink connector which then inserts the message into GridDB. Finally, the DataViewer reads the message from GridDB. This project will also show you how to configure the MQTT-Kafka connector to allow for multiple MQTT clients from multiple machines to send data to a single, remote GridDB database through Kafka.