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Well finally I figured it out myself

We have to use DrawFilter and there use resultSet etc and use page property as a parameter.
There seems to be no other simpler way.

If anyone needs any help in ever implementing the same. Pls feel free to ping me

With Postman and soapui you are hitting the url straight not via a network protocol, thus it giving 200.
What I think  you should check system logs to see whats the error thrown by the rest application. I feel its just an authentication / authorization issue

Feel free to share logs if it doesn't resolve

Thanx to all and esp to Eduard

I used a mix of Eduard's code, docs, EnsLib.PubSubOperation and some of my code

From my BP -  I am calling the PubSubBo with a response of arrays that gives me targets in a string array 

- BP then sends to all targets from a call inside a loop of targets array. The target of which is set dynamically from context of the loop element.