x/grpcClient Component: v0.25.0+ gRPC client. Allows dynamic invocation of gRPC services.

The gRPC server must register the gRPC reflection service. This allows clients to query the services and methods supported by the server at runtime.

Configuration

This component allows reusing shared connection clients through the server field. Refer to Component Connection Reuse.

Field	Type	Description	Default
server	string	gRPC service address, format: hostname:port	None
service	string	gRPC service name, can use Component Configuration Variables	None
method	string	gRPC method name, can use Component Configuration Variables	None
request	string	Request parameters, if empty, use the current message payload. Use JSON encoded, structure must match the requirements of service/method	None
headers	map	Request header, can using Component Configuration Variables.

Relation Type

• Success: Execution successful, send the message to the Success chain
• Failure: Execution failed, send the message to the Failure chain

Execution Result

The query result is assigned to the message payload and passed to the next node.

Example

1. Define a gRPC service as follows:

syntax = "proto3";

package helloworld;

option go_package = ".;helloworld";

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

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

2. Generate protobuf code

protoc --go_out=. --go-grpc_out=. helloworld.proto

3. Run the server

package main

import (
	"context"
	pb "github.com/rulego/rulego-components/external/grpc/testdata/helloworld"
	"google.golang.org/grpc"
	"google.golang.org/grpc/reflection"
	"log"
	"net"
)

// server is the server implementation of the Greeter service
type server struct {
	pb.UnimplementedGreeterServer
}

// SayHello implements the SayHello method of the Greeter service
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
	log.Printf("Received: %v", in.GetName())
	return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}

func main() {
	listen, err := net.Listen("tcp", ":50051")
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterGreeterServer(s, &server{})
	// Register gRPC reflection service
	reflection.Register(s)
	// Start the server
	if err := s.Serve(listen); err != nil {
		log.Fatalf("failed to serve: %v", err)
	}
}

4. Call the server through the grpcClient component

{
    "id": "s1",
    "type": "x/grpcClient",
    "name": "call grpc service",
    "configuration": {
      "server":  "127.0.0.1:50051",
      "service": "helloworld.Greeter",
      "method":  "SayHello",
      "request": "{\"name\": \"lulu\"}"
    }
}