Could we add some examples for each module?

[umialpha]

Hi, I am glad to find this powerful pkg. However, their is no tutorial or example to show how to use it. Could we add some tutorials or examples for each module?

[umialpha]

BTW, my usecase is as follows, we deploy client's gRPC servers in our cluster. client will send request to our proxy saying" I want ADD 1, 2 ", our proxy will parse the request and act like the real gRPC client, sending request to multiple gRPC server, return the fastest response to client.

ClientA ----> Proxy -- --> Server A & B

[Paxa]

+1 for examples

[Paxa]

I can suggest some example:

• Parse .proto file
• Create dynamic message
• Send message to GRPC
• marshal and unmarshal binary data

package main

import (
	"context"
	"fmt"
	"log"
	"os"

	"github.com/jhump/protoreflect/desc"
	"github.com/jhump/protoreflect/desc/protoparse"
	"github.com/jhump/protoreflect/dynamic"
	"github.com/jhump/protoreflect/dynamic/grpcdynamic"
	"google.golang.org/grpc"
)

const GRPC_SERVER = "127.0.0.1:10000"

// proto file https://github.com/grpc/grpc-go/blob/master/examples/route_guide/routeguide/route_guide.proto

func loadProto() *desc.FileDescriptor {
	parser := protoparse.Parser{}
	parser.ImportPaths = []string{
		os.Getenv("HOME") + "/go/src/google.golang.org/grpc/examples/route_guide/routeguide",
	}

	descs, err := parser.ParseFiles("route_guide.proto")

	if err != nil {
		panic(err)
	}

	log.Printf("Loaded descriptor content:")

	for _, desc := range descs {
		for _, service := range desc.GetServices() {
			log.Printf("> service %s", service.GetFullyQualifiedName())
			for _, method := range service.GetMethods() {
				log.Printf("  * method %s (%s) %s",
					method.GetFullyQualifiedName(),
					method.GetInputType().GetFullyQualifiedName(),
					method.GetOutputType().GetFullyQualifiedName(),
				)
			}
		}
		for _, msg := range desc.GetMessageTypes() {
			log.Printf("- message %s", msg.GetFullyQualifiedName())
		}
	}

	return descs[0]
}

// Dynamically create message using parsed proto descriptor
func composeMessage(descriptor *desc.FileDescriptor) *dynamic.Message {
	messageDesc := descriptor.FindMessage("routeguide.Point")
	if messageDesc == nil {
		panic(fmt.Errorf("Can't find message"))
	}
	message := dynamic.NewMessage(messageDesc)

	/*
		message Point {
			int32 latitude = 1;
			int32 longitude = 2;
		}
	*/

	message.SetFieldByName("latitude", int32(12345678))
	message.SetFieldByName("longitude", int32(87654321))

	return message
}

// Require GRPC server running
//    cd ~/go/src/google.golang.org/grpc/examples/route_guide
//    go run server/server.go
//
func callGrpc(descriptor *desc.FileDescriptor) {
	serviceName := "routeguide.RouteGuide"
	methodName := "GetFeature"

	log.Printf("Looking for serviceName %s methodName %s", serviceName, methodName)

	// FIND DYNAMIC DESCRIPTORS FOR SERVICE AND METHOD

	serviceDesc := descriptor.FindService(serviceName)
	if serviceDesc == nil {
		panic(fmt.Errorf("Can't find service %s", serviceName))
	}

	methodDesc := serviceDesc.FindMethodByName(methodName)
	if methodDesc == nil {
		panic(fmt.Errorf("Can't find method %s in service %s", methodName, serviceName))
	}

	// CREATE GRPC CLIENT

	log.Printf("Creating GRPC client for %s", GRPC_SERVER)
	conn, err := grpc.Dial(GRPC_SERVER, grpc.WithInsecure())
	if err != nil {
		panic(err)
	}
	defer conn.Close()

	grpcClient := grpcdynamic.NewStub(conn)

	// SENDING MESSAGE

	message := composeMessage(descriptor)
	response, err := grpcClient.InvokeRpc(context.TODO(), methodDesc, message)

	if err != nil {
		panic(err)
	}

	log.Printf("response %#v", response)

	json, err := response.(*dynamic.Message).MarshalJSON()
	log.Printf("response json %s %v", json, err)
}

// Convert dynamic.Message to binary string (proto encoded) and parse proto string to dynamic.Message
func toAndFromBin(descriptor *desc.FileDescriptor) {
	message := composeMessage(descriptor)

	data, err := message.Marshal()
	log.Printf("Binary data %v  %v", data, err)

	parsedDessage := dynamic.NewMessage(descriptor.FindMessage("routeguide.Point"))
	err = parsedDessage.Unmarshal(data)

	log.Printf("Parsed from binary %v  %v", message, err)
}

func main() {
	descriptor := loadProto()

	fmt.Println("")
	log.Printf("Creating message dynamicly of type routeguide.Point")
	fmt.Println("")

	point := composeMessage(descriptor)
	json, err := point.MarshalJSON()
	log.Printf("message routeguide.Point as json: %s %v", json, err)

	fmt.Println("")
	log.Printf("Calling grpc endpoint routeguide.Point")
	fmt.Println("")

	callGrpc(descriptor)

	fmt.Println("")
	log.Printf("Work with binary strings")
	fmt.Println("")

	toAndFromBin(descriptor)
}

[umialpha]

@Paxa Thanks a lot. Your example explains pretty well.

[LSTPro]

@Paxa How do I read the incoming metadata after invokeRPC call
i.e., response, err := grpcClient.InvokeRpc(context.TODO(), methodDesc, message)

[jhump]

@LSTPro, that's really a grpc-go question, not specific to this repo.
https://github.com/grpc/grpc-go/blob/master/Documentation/grpc-metadata.md#receiving-metadata

[LSTPro]

@jhump The link provided was helpful, Thank you!