Minus creating your own managers, caching, strategies for optimal performance, your best bet with apis as is to assemble calls behind the scenes. You may want to consider broadening your funnel and using activity which includes more than content but has a better data structure for spanning across domains, or perhaps using advanced search queries.
Depending on your desired performance profile and requirements this could range in complexity, but very doable ... Is followed activity/content too broad?
Thanks for the inputs.The requirement expects the wiget to give options to the user to configure the containers(say, a dropdown having list of all existing containers which should be a multiple select type) from where the data has to be fetched.Is there any way/API to do this with the existing code?
Looking at your suggestions, can you please provide some pointers to how to manipulate the existing filter so as to accommodate this requirement within and fetch data correspondingly?
ResultFilters are traditionally a Manager construct, and tend to be single domain (i.e. document, thread, OR blog post). There is the SearchManager which allows you to construct a query with similar filters, but OOTB I believe you are limited to a finite set of containers with this construct as well.
In general, the requirements you are describing are not conducive for a successful outcome for the end-user. In general, you will most likely provide them with too much content to which point it is not actionable, or users will be turned-off by the inefficiency of after-the-fact concatenation/relevance. I've seen this from other non-Jive systems as well ... so this isn't a Jive thing as much as a pattern. If you can distill the inputs to some predictable set of patterns, then you can construct caches/queries and an integrated access manager to optimize the performance. If you cant come to an agreement like this on the inputs, then adopting an interface that allows you to smartly load on demand might generate some benefit.
I hope this helps give you some direction, while admitedly it may not be what you are asking for ... it will hopefully lead you to some answers.