The aggregation i mentioned in the query was about the aggregation of an object , a parent has a child object of item type and my question was how do we create that in the schema if not a 1-1 or a 1-N relationship linking. Thank you
Thank you but was not trying that i was referring to orchestration of campaign API's to be called thru a single API and was able to do it through Azure API
This page was updated on 24 so i thought it would be useful, anyway you can create a mock service expose it and use that api in your external activity.
Please follow this link and also the version should be 20.2 or 20.3.https://docs.adobe.com/content/help/en/campaign-standard-learn/tutorials/managing-processes-and-data/data-management-activities/external-api-activity.html