README.adoc

Spring boot starter for gRPC framework.

Features

Auto-configures and runs the embedded gRPC server with @GRpcService-enabled beans as part of spring-boot application.

Setup

repositories {
   jcenter()
   // maven { url "http://oss.jfrog.org/oss-snapshot-local" } //for snashot builds

}
dependencies {
    compile('org.lognet:grpc-spring-boot-starter:1.0.0')
}

Note	If you are using protobuf version lower than 3.0.0, please use org.lognet:grpc-spring-boot-starter:0.0.3

Usage

• Start by generating stub and server interface(s) from your .proto file(s).

• Annotate your server interface implementation(s) with @org.lognet.springboot.grpc.GRpcService

• Optionally configure the server port in your application.yml/properties. Default port is 6565

 grpc:
    port : 6565

Show case

In the 'grpc-spring-boot-starter-demo' project you can find fully functional example with integration test.

Service implementation

The service definition from .proto file looks like this :

service Greeter {
    rpc SayHello ( HelloRequest) returns (  HelloReply) {}
}

Note the generated io.grpc.examples.GreeterGrpc.GreeterImplBase class that extends io.grpc.BindableService.(The generated classes were intentionally committed for demo purposes).

All you need to do is to annotate your service implementation with @org.lognet.springboot.grpc.GRpcService

    @GRpcService
    public static class GreeterService extends  GreeterGrpc.GreeterImplBase{
        @Override
        public void sayHello(GreeterOuterClass.HelloRequest request, StreamObserver<GreeterOuterClass.HelloReply> responseObserver) {
            final GreeterOuterClass.HelloReply.Builder replyBuilder = GreeterOuterClass.HelloReply.newBuilder().setMessage("Hello " + request.getName());
            responseObserver.onNext(replyBuilder.build());
            responseObserver.onCompleted();
        }
    }

Interceptors support

The starter supports the registration of two kinds of interceptors: Global and Per Service.
In both cases the interceptor has to implement io.grpc.ServerInterceptor interface.

• Per service

@GRpcService(interceptors = { LogInterceptor.class })
public  class GreeterService extends  GreeterGrpc.GreeterImplBase{
    // ommited
}

LogInterceptor will be instantiated via spring factory if there is bean of type LogInterceptor, or via no-args constructor otherwise.

• Global

@GRpcGlobalInterceptor
public  class MyInterceptor implements ServerInterceptor{
    // ommited
}

The annotation on java config factory method is also supported :

 @Configuration
 public class MyConfig{
     @Bean
     @GRpcGlobalInterceptor
     public  ServerInterceptor globalInterceptor(){
         return new ServerInterceptor(){
             @Override
             public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call, Metadata headers, ServerCallHandler<ReqT, RespT> next) {
                // your logic here
                 return next.startCall(call, headers);
             }
         };
     }
 }

The particular service also has the opportunity to disable the global interceptors :

@GRpcService(applyGlobalInterceptors = false)
public  class GreeterService extends  GreeterGrpc.GreeterImplBase{
    // ommited
}

Custom gRPC Server Configuration

To intercept the io.grpc.ServerBuilder instance used to build the io.grpc.Server, you can add bean that inherits from org.lognet.springboot.grpc.GRpcServerBuilderConfigurer to your context and override the configure method.
By the time of invocation of configure method, all discovered services, including theirs interceptors, had been added to the passed builder.
In your implementation of configure method, you can continue with passed instance of ServerBuilder by adding your configuration:

@Component
public class MyGRpcServerBuilderConfigurer extends GRpcServerBuilderConfigurer(){
        @Override
        public ServerBuilder<?> configure(ServerBuilder<?> serverBuilder){
            return serverBuilder
                .executor(YOUR EXECUTOR INSTANCE)
                .compressorRegistry(YOUR COMPRESSION REGISTRY)
                .decompressorRegistry(YOUR DECOMPRESSION REGISTRY)
                .useTransportSecurity(YOUR TRANSPORT SECURITY SETTINGS);

        }
    };
}

or return completely new instance of ServerBuilder :

@Component
public class MyGRpcServerBuilderConfigurer extends GRpcServerBuilderConfigurer(){
        @Override
        public ServerBuilder<?> configure(ServerBuilder<?> serverBuilder){
            return ServerBuilder.forPort(YOUR PORT)
                .executor(YOUR EXECUTOR INSTANCE)
                .compressorRegistry(YOUR COMPRESSION REGISTRY)
                .decompressorRegistry(YOUR DECOMPRESSION REGISTRY)
                .useTransportSecurity(YOUR TRANSPORT SECURITY SETTINGS);

        }
    };
}

Note	In this case you should also take care about adding the services to the fresh instance of ServerBuilder

License

Apache 2.0