This repo provides alternate "channel" implementations for gRPC, that provide
the same interface and semantics (and re-use gRPC generated code) but over a
transport other than the standard HTTP/2-based one provided by the
google.golang.org/grpc package.
The ability to use alternate transports, such as HTTP 1.1 or in-process channels, is often quite useful, for testing but also for providing RPC semantics on top of different communication primitives. Implementations could even be built that use things like web sockets or streaming frameworks (like publish/subscribe systems or message brokers).
This repo contains two alternate transports: an HTTP 1.1 implementation (which supports all stream kinds other than full-duplex bidi streams) and an in-process transport (which allows a process to dispatch handlers implemented in the same program without needing to serialize and de-serialize messages over the loopback network interface).
The root grpchan package was created to provide its Channel and ServiceRegistry
interfaces; these were the core interfaces to implement when building a new transport.
The package also includes some helpers related to these interfaces as well as a simple
map-backed registry.
These two interfaces were needed prior to grpc-go v1.32.0, as was the use of a
proto plugin
that would generate additional functions alongside generated gRPC code, allowing
the use of these abstractions. But as of v1.32.0 of the grpc-go module, there now
exist grpc.ClientConnInterface and grpc.ServiceRegistrar, which are what a new
transport must implement (grpchan's interfaces are now deprecated aliases of these
two). As long as you are using protoc-gen-go-grpc v1.0.1 or newer for code
generation, gRPC generated code works out-of-the-box with grpchan. (Note that the
old protoc-gen-go plugin, provided by the github.com/golang/protobuf repo, could
also generate gRPC code, but its output does not work with grpchan without the
proto plugin mentioned above.)