KSQL makes it easy to read, write, and process streaming data in real-time, at scale, using SQL-like semantics. It offers an easy way to express stream processing transformations as an alternative to writing an application in a programming language such as Java or Python. https://www.confluent.io/product/ksql/
With WinCC OA Java (https://github.com/vogler75/oa4j) we can stream data from WinCC OA to Apache Kafka, use KSQL to produce some insights and send it back to WinCC OA by using a WinCC OA Driver written in Java connected to Kafka.
Attached you will find a docker-compose.yml to setup KSQL + WinCC OA Connector and Driver to test it. Just use “docker-compose up -d” to start up everything. Before you should set the “data” and “event” environment variables in the docker-compose.yml to point to a running WinCC OA project.
root@docker1:~/docker/builds/winccoa# docker-compose up -d Creating winccoa_frontend_1 ==> collect data from OA and publish it by ZeroMQ Creating winccoa_backend-kafka_1 ==> get the data from the Frontend and write it to Kafka Creating winccoa_driver-kafka_1 ==> OA driver to read data from kafka. Creating winccoa_zookeeper_1 Creating winccoa_kafka_1 Creating winccoa_schema-registry_1 Creating winccoa_ksql-cli_1
We use Docker to startup WinCCOA Mangers (frontend, backend) and Drivers.
Afterwards you can start KSQL: docker-compose exec ksql-cli ksql-cli local –bootstrap-server kafka:29092
Create a stream of the topic which is sent from WinCC OA to kafka (currently every change of value in WinCC OA is sent to Kafka):
CREATE STREAM Scada_FloatVar (TimeMS BIGINT, Status BIGINT, Value DOUBLE) WITH (kafka_topic=’Scada_FloatVar’, value_format=’JSON’);
Create a result table in KSQL which will be read by the WinCC OA Driver, here we detect if a datapoint changes more often than 5 times in 10 seconds. Just a simple example to show how KSQL can be used:
CREATE TABLE result WITH (PARTITIONS=1) AS SELECT rowkey AS “Name”, count(*) AS “Value” FROM Scada_FloatVar WINDOW TUMBLING (size 10 second) GROUP BY rowkey HAVING count(*) > 5;
In WinCC OA you should put a peripheral address on a datapoint with the example driver (num 4) to get the result back (you will need the panels and scripts from here https://github.com/vogler75/oa4j/tree/master/Project/Drivers/Kafka to use the driver).