Streaming RPC's using gRPC

gRPC is a language-neutral, platform-neutral RPC framework that is quickly taking on JSON/HTTP as the recommended way to communicate between microservices.

Its main selling points are:

• Communication is based on HTTP2 transport. This provides all the advantages of the HTTP2 (compression, multiplexing, streaming)
• Well-defined schemas via Protocol Buffers 3
• Automatic client code generation for 10 different languages.
• Bi-directional streaming

By default, gRPC uses Protocol Buffers as the Interface Definition Language (IDL) and as its underlying message interchange format.

In this project, we'll implement a simple PrimeFactorService that returns a stream of the prime factors of the numbers passed to it in a request. I decided to make my gRPC server in Go and client in Python. The client program will read from stdin and will immediately push it to the service.

Generate gRPC code for server and client

We are going to use gRPC to generate libraries for Go and Python 3. To generate the Go code, you'll need to install protoc.

# Python client
$ pip3 install -U grpcio grpcio-tools
$ python3 -m grpc_tools.protoc -I protobuf/ --python_out=. --grpc_python_out=. protobuf/primefactor.proto

# Go server
$ go get google.golang.org/grpc
$ go install google.golang.org/protobuf/cmd/protoc-gen-go
$ protoc --proto_path=protobuf protobuf/primefactor.proto --go_out=. --go-grpc_out=.

The first command will generate primefactor_pb2.py and primefactor_pb2_grpc.py. The latter will generate primefactor.pb.go.

To start the server, simply run:

go run server.go

You can run the client using:

python3 client.py