The json_stringn function should be used instead of the json_string to
allow null characters as well as non-null terminated strings to be
embedded in the JSON values.
The CDC example Python programs now decode the data as UTF-8 instead of
ASCII.
As the cdc_kafka_producer script is an example, it should flush the
producer after every new record. This should make it easier to see that
events from MaxScale are sent to Kafka.
There's no need to process the JSON twice as the Kafka producer is
expected to be used with the Python CDC client which already splits the
JSON with newlines.
