I'm not an expert on gRPC, but the following snippets from the official FAQ might help you:
Why is gRPC better than any binary blob over HTTP/2?
This is largely what gRPC is on the wire. However gRPC is also a set of libraries that will provide higher-level features consistently across platforms that common HTTP libraries typically do not. Examples of such features include:
- interaction with flow-control at the application layer
- cascading call-cancellation
- load balancing & failover
Can I use gRPC with my favorite data format (JSON, Protobuf, Thrift, XML) ?
Yes. gRPC is designed to be extensible to support multiple content types. The initial release contains support for Protobuf and with external support for other content types such as FlatBuffers and Thrift, at varying levels of maturity.
So it appears that gRPC is not really tied to the particular binary format or whatever; it's more like a framework/standard for writing remote APIs.
And yes, there is a generator which creates stubs from your service definitions. There is a plugin architecture so any kind of language/platform should be able to add support.