If I understand your post correctly, perhaps this would do the trick.
http://wordpress.org/extend/plugins/json-api/
It has 3 controllers:
Post:
create_post
Core:
info get_recent_posts get_post get_page get_date_posts get_category_posts get_tag_posts get_author_posts get_search_results get_date_index get_category_index get_tag_index get_author_index get_page_index get_nonce
Respond:
submit_comment
