ScalaPB-Reactor

The ScalaPB gRPC generator to run Reactive gRPC server and client on top Project Reactor's Scala extension.

Highlights

• Uses Reactive gRPC for Java Runtime which provides Reactive Streams on top of gRPC's back-pressure support.
• Uses Reactor Scala Extensions for easily building stream requests and responses.

Installation

Add the following configuration to project/plugins.sbt.

addSbtPlugin("com.thesamet" % "sbt-protoc" % "1.0.4")
libraryDependencies += "kr.ikhoon.scalapb-reactor" %% "scalapb-reactor-codegen" % "<latest-version>"

Add the following configuration to build.sbt.

PB.targets in Compile := Seq(
  scalapb.gen() -> (sourceManaged in Compile).value,
  scalapb.reactor.ReactorCodeGenerator -> (sourceManaged in Compile).value
)

ScalaPB-Reactor 0.3.0 currently supports Scala 2.12 and 2.13. Please use 0.1.0 for Scala 2.11.

Example

ScalaPB-Reactor generates your stub file to <package>.<file-name>.Reactor<service-name>. The following proto file will be generated to com.example.test_service.ReactorTestService.

// file: test_service.proto

syntax = "proto3";

package com.example;

message Request {
    string in = 1;
}

message Response {
    string out = 1;
}

service TestService {
    rpc Unary(Request) returns (Response);
    rpc ServerStreaming(Request) returns (stream Response);
    rpc ClientStreaming(stream Request) returns (Response);
    rpc BidiStreaming(stream Request) returns (stream Response);
}

The generated gRPC stub for Reactor contains the following structure.

object ReactorTestServiceGrpc {
  // Implement this trait for your service.
  trait ReactorTestService {
    def unary(request: Request): SMono[Response]
    def serverStreaming(request: Request): SFlux[Response]
    def clientStreaming(request: SFlux[Request]): SMono[Response]
    def bidiStreaming(request: SFlux[Request]): SFlux[Response]
  }
  
  object ReactorTestService {
    // Use this method to bind your service with gRPC server
    def bindService(serviceImpl: ReactorTestService): ServerServiceDefinition = {
       ... 
    }
  }
  
  // You use this class for creating gRPC client stub.
  class ReactorTestServiceStub(channel: Channel, options: CallOptions) 
    extends AbstractStub[ReactorTestServiceStub](channel, options) with ReactorTestService {
  }
}

Visit examples to find a fully working example.