[raspasov]

Incomplete or completely lacking documentation for Objective C and Java, weird bugs, random disconnects. Overall it feels like the Ruby on Rails of networking - an opinionated package/framework that tries to do too much. Also, the whole concept of "as easy as a a local functional call" is a flawed, leaky abstraction.

[euyyn]

I'm responsible for the Objective-C part, so please let me know of anything we can improve there. We have a couple of tutorials at http://www.grpc.io/docs/tutorials/ and a quick-start guide at http://www.grpc.io/docs/quickstart/objective-c.html . For bugs and connectivity problems, filing a GitHub issue would be super appreciated.

If you look at the example code, you'll see that RPCs aren't modeled exactly as local function calls. You're right that that wouldn't work very well. The libraries for all or most languages let you make RPCs asynchronously, without blocking the thread. And all of them provide with ways to write and read RPC metadata (headers and trailers).