This is the scenario: There are say 3 sites - A, B and C. Sites A and B have several custom posts. Now, from site C, I'd like to make a search for the posts in sites A and B.
After reading up through online resources, I realized that xml-rpc can be used to achieve this. I read about adding custom functions, but I didn't understand where exactly the add_filter method is to be put (along with the custom method definition).
Can someone guide me along?