Preface

• There are many installation tutorials online. Due to updates in gRPC, many commands may become obsolete. This article reflects the current state at the time of writing.
• If you encounter issues, the best approach is to refer to the official documentation

Installation

1. First install Go
2. Install the protoc compiler https://grpc.io/docs/protoc-installation/
   • The protoc compiler is used to compile .proto files containing service and message definitions
   • Download the zip file matching your OS and architecture (e.g., protoc-3.19.4-linux-x86_64.zip for WSL)
     • https://github.com/protocolbuffers/protobuf/releases
   • Extract the downloaded package:
     • unzip protoc-3.19.4-linux-x86_64.zip -d $HOME/.local
   • Add to PATH:
     • vim ~/.bashrc and add:
     • export PATH="$PATH:$HOME/.local/bin"
     • source ~/.bashrc to refresh environment variables
   • Verify with protoc --version
3. Install Go plugins
   • The protoc compiler requires these plugins to generate Go code:
     • go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.26
   • gRPC code generator plugin (previously included in protoc-gen-go):
     • go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.1

Core Concepts

• gRPC supports four service method types:
  • Unary RPC: Client sends single request, server returns single response (like normal function call)
  • Server streaming: Client sends request, gets stream to read message sequence
  • Client streaming: Client sends stream of messages, server returns single response
  • Bidirectional streaming: Both sides send message streams independently
• Use repeated for bounded datasets that can be generated quickly, stream for large/potentially unbounded datasets

Example Implementation

Project Setup

mkdir grpc-demo && cd grpc-demo
go mod init github.com/seth-shi/grpc-demo

Protocol Definitions

pb/goods.proto:

syntax = "proto3";
package pb;
option go_package="github.com/seth-shi/grpc-demo/pb";

service Goods {
    rpc Show(GoodsShowRequest) returns (GoodsData);
}

message GoodsShowRequest { int64 id = 1; }
message GoodsData {
    int64 id = 1;
    string name = 2;
    double amount = 3;
}

pb/order.proto:

syntax = "proto3";
package pb;
option go_package="github.com/seth-shi/grpc-demo/pb";

service Order {
    rpc Index(OrderIndexRequest) returns (OrderIndexResponse);
    rpc Store(OrderStoreRequest) returns (OrderData);
}

message OrderIndexRequest { int64 userId = 1; }
message OrderIndexResponse { repeated OrderData data = 1; }
message OrderStoreRequest {
    int64 goodsId = 1;
    int64 goodsNumber = 2;
    int64 userId = 3;
    double Amount = 4;
    string goodsName = 5;
}
message OrderData {
    int64 no = 1;
    double amount = 2;
    int64 number = 3;
    int64 goodsId = 4;
    string goodsName = 5;
}

Generate Go code:

protoc --go_out=. --go_opt=paths=source_relative \
       --go-grpc_out=. --go-grpc_opt=paths=source_relative \
       pb/*.proto
go mod tidy

Service Implementations

goods/main.go:

package main
// ... goods service implementation ...

order/main.go:

package main
// ... order service implementation ...

API Gateway

api/main.go:

package main
// ... API implementation with Gin ...

Running the System

# Start services in separate terminals
go run goods/main.go
go run order/main.go 
go run api/main.go

Common Errors

• rpc error: code = Unavailable desc = connection error:
  • Common in WSL environments - try running services directly on host machine
  • Ensure ports are not blocked by firewall
  • Verify service addresses match in client connections

This implementation demonstrates basic gRPC patterns including:

• Protocol definition with Protobuf
• Service implementation patterns
• Client-server communication
• Error handling basics
• API gateway pattern