POSIX doesn't define a service API for (HTTP, local, or otherwise exposed) services, but if adherence to an existing API spec from the height of SOA is important, there is Service Component Architecture (SCA) which has bindings to C (or other native PL), Java/JVM, and other relevant calling conventions. There used to be multiple implementations of SCA for C++ (Apache Tuscany, Trentino/Siemens, and others) but C++ name mangling is of course a PITA for binary forward compatibility.
This looks really useful! I've just started working on a (mostly pedagogical) little project making a chat server/client in C and started reading through Beej's guide to networking which is great for the fundamentals but I was struggling with deciding how I want to structure my larger code in terms of sockets, clients, multiplexing, etc. I may just end up using your library if it fits (after reading through it some more), else take inspiration from it at the very least.
Poser: The ultimate insult a skater could call anyone else.
From a cursory glance this seems to be a contender for libuv, so I would like to learn more about motivation for this project. Unfortunately, none is given, as well as why is it limited only to POSIX APIs.