I think that this can be deferred to next PR. What I would suggest for the next PR is to have several notification scripts:

* notification-json-simple.sh (values with string using JSON)
* notification-json-compound.sh (values with objects/vector using JSON)
* notification-xml-simple.sh (value with string using XML)
* notification-xml-compound.sh (values with objects/vectors using XML)

(The two first ones are already in the repo, although maybe with a different name... I don't remember exactly).

and ensure that both HDFS and CKAN sinks works corrrectly for the 4 cases.