API 8: rm-mms
Function: request_plan
Input: site, user_id, P/P, request_token, return_id
Input: set_of (bundle)
Return: plan_token

Function: did_not_work
Input: set_of (set_of (file_name) url_source, url_destination
source_properties, target_properties, link_properties)
return: ack

API 8’: mms-rm
Function: here_is_the_plan (again)
Input: plan_token
Input: ordered_set_of (file_name, url_source, url_destination, file_size
source_properties, target_properties, link_properties)
Input: partial/complete
Return: ack

Note: some requests may be limited as to where the files can be cached into
(e.g. objectivity sites). Perhaps it is enough for the catalog to know about
types of sites). Type of requests need to give hint about their type.