I need to fetch the data using REST Endpoints(returns JSON file) and load the data(JSON) into Cassandra cluster which is sitting on AWS.
This is a migration effort, which involves millions of records. No access to source DB. Only access to REST End points.

What are the options I have?
What is the programming language to use?(I am thinking of Python or any scripting language)?
Since I will have to migrate millions of records, I would like to process the jobs concurrently.
What are the challenges?

Thanks for the time and help.
--GK.
Cassandra 2.2.0 give feature to insert and get data as JSON .So you can use that .
Like for insert json data .
CREATE TABLE test.example (
    id int PRIMARY KEY,
    id2 int,
    id3 int
) ;
cqlsh >  INSERT INTO example JSON '{"id":10,"id2":10,"id3":10}' ;
For Select data as Json :
cqlsh >  SELECT json  * FROM  example;
 [json]
{"id": 10, "id2": 10, "id3": 10}
Data Migration to Cassandra using REST End points