With the tasks you're trying to achieve, you should have both the budget and the ability to hire competent engineers anywhere in the world. Maybe not to hire hundreds of them, or keep them employed indefinitely, but a few dollars (or yen or whatever) invested wisely at the beginning can spell the difference between success and failure, or between having a model that works efficiently and profitably, and one that has to be re-engineered and costs many many times what would have been invested up front.
Oh, btw, NNG has pretty good docs now. See the reference manual on the site ( nanomsg.github.io/nng/man ) or leanpub (purchase - https://leanpub.com/nngmanual )
Latest NNG (nanomsg-next-gen) has the ability to support HTTP and SP protocol in the same application. You have to write your own code to map the two and add business logic, but it should be pretty straight-forward.
NNG doesn't have an RDMA style transport today, although that can be developed. (Staysail Systems offers commercial support of NNG and nanomsg, including custom development.)
Ultimately, there are lots of ways to solve this, but you need to have a better understanding of your particular needs -- the fact that you're using DPDK and RDMA suggests to me that latency and performance are very important to you, and some more assessment would be required to make a good recommendation.
If you want, you can reach out to me -- I'm the author of NNG and now maintainer of nanomsg. I'm also the CTO for Staysail, so if you need commercial help, I can offer that. (See www.staystail.tech or [email protected] for contact info.)
It is well worth reading.