Connect Cassandra NoSQL DB and get the response as JSON response
You can query your data and retrieve a JSON string with the following type of queries:
SELECT JSON keyspace_name, durable_writes FROM system_schema.keyspaces ;This will return you a json string that maps the keys (column name) with the corresponding value.See the doc here: http://cassandra.apache.org/doc/latest/cql/json.html
Then you could re-insert the json string in Cassandra, if that's what you want.
If you need to do that at scale, or as a streaming job, you would want to look at using Spark on top of Cassandra: Load your Cassandra data into spark, use spark to transform that into a JSON string, and reinsert into Cassandra or another db.