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Lakhan Samani
Lakhan Samani

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Defining gRPC APIs with Protobuf - Part 2

#protobuf #grpc #go #microservices

In Part 1, we set up our project structure. Now, we’ll:
✅ Define User and Order APIs
✅ Generate gRPC code from .proto files.

We have created apis folder so lets navigate to that folder and define our apis there.

cd ecom-grpc/apis
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Note: Please replace the github user name and repo in each of the following folder

Step 1: Install Protobuf Compiler

Before writing .proto files, install protoc:

🔹 Mac (Homebrew) 

brew install protobuf
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🔹 Ubuntu/Linux 

sudo apt update && sudo apt install -y protobuf-compiler
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🔹 Windows

Download from protobuf releases.

Verify installation:

protoc --version
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Step 2: Define User Service API

create user/v1/user.proto file in apis repo

mkdir -p user/v1/ touch user/v1/user.proto
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syntax = "proto3"; package user.v1; option go_package = "github.com/lakhansamani/ecom-grpc-apis/user/v1"; // User Service definition service UserService { // Register API to register a new user // Permission: none rpc Register(RegisterRequest) returns (RegisterResponse); // Login API to login a user // Permission: none rpc Login(LoginRequest) returns (LoginResponse); // Me API to get user details // Permission: authenticated user rpc Me(MeRequest) returns (MeResponse); } // User model message User { string id = 1; string name = 2; string email = 3; } // Register API message RegisterRequest { string name = 1; string email = 2; string password = 3; } message RegisterResponse { string user_id = 1; } // Login API message LoginRequest { string email = 1; string password = 2; } message LoginResponse { string token = 1; } // Me API (token will be taken from gRPC metadata) message MeRequest {} message MeResponse { User user = 1; }
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New API methods

  • Register → Registers a new user and returns a JWT token.
  • Login → Authenticates a user and returns a JWT token.
  • Me → Returns user details using the JWT token.

🔹 Step 3: Define Order Service API

create order/v1/order.proto file in apis repo

mkdir -p order/v1/ touch order/v1/order.proto
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syntax = "proto3"; package order.v1; option go_package = "github.com/lakhansamani/ecom-grpc-apis/order/v1"; service OrderService { // CreateOrder API to create a new order // Permission: authenticated user rpc CreateOrder(CreateOrderRequest) returns (CreateOrderResponse); // GetOrder API to get order details // Permission: authenticated user who created the order rpc GetOrder(GetOrderRequest) returns (GetOrderResponse); } // Order model message Order { string id = 1; string user_id = 2; string product = 3; int32 quantity = 4; double unit_price = 5; } // CreateOrder request API message CreateOrderRequest { string product = 1; int32 quantity = 2; } // CreateOrder response API message CreateOrderResponse { Order order = 1; } // GetOrder request API message GetOrderRequest { string id = 1; } // GetOrder response API message GetOrderResponse { Order order = 1; }
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New API methods

  • CreateOrder - to create order
  • GetOrder - to get order information

🔹 Step 4: Generate gRPC Code

To simplify the process lets create a Makefile at the root of apis repo which we can run to generate the go-grpc code.

touch Makefile
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all: build build: protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=require_unimplemented_servers=false:. --go-grpc_opt=paths=source_relative user/v1/user.proto protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=require_unimplemented_servers=false:. --go-grpc_opt=paths=source_relative order/v1/order.proto
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Run make command to generate the files and push to github.

Code Link

🎯 Next Steps

  • 🚀 Now that we have the User & Order Service protobuf, in Part 3, we will:
  • ✅ Implement User Service.
  • ✅ Implement Order Service.

Stay tuned! 🚀

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