B4J Question Web APP: Load JSON with form submit

Hi
I am starting to using B4J and try to fetch information from a json file with a html form.
A form posts a link with attributes and fetches a json result list. A part of this json list shall be displayed on a webpage.
The problem:
The json file is loaded AFTER the response is sent and displayed in the web browser.

I tried to put together a slimmed down version of my app and append it here.

Does anybody have a hint?

Thanks a lot
David