gRPC in 2026: Building High-Performance APIs for Modern Distributed Systems

REST has served us well, but for high-performance microservices communication, gRPC offers compelling advantages: binary serialization, strong typing, streaming support, and automatic code generation. Let’s dive deep into building production-ready gRPC services.

Network Infrastructure Photo by Jordan Harrison on Unsplash

Why gRPC in 2026?

Performance Comparison

Feature	REST/JSON	gRPC/Protobuf
Serialization	Text (larger)	Binary (10x smaller)
Type Safety	Runtime validation	Compile-time checks
Streaming	Workarounds needed	Native support
Code Gen	OpenAPI (optional)	Built-in, mandatory
HTTP Version	HTTP/1.1 or 2	HTTP/2 required

Getting Started

Define Your Service

// order_service.proto
syntax = "proto3";

package ecommerce.orders.v1;

import "google/protobuf/timestamp.proto";
import "google/protobuf/empty.proto";

option go_package = "github.com/mycompany/ecommerce/orders/v1";

// Order represents a customer order
message Order {
  string id = 1;
  string customer_id = 2;
  repeated OrderItem items = 3;
  OrderStatus status = 4;
  Money total = 5;
  google.protobuf.Timestamp created_at = 6;
  google.protobuf.Timestamp updated_at = 7;
}

message OrderItem {
  string product_id = 1;
  string product_name = 2;
  int32 quantity = 3;
  Money unit_price = 4;
}

message Money {
  string currency_code = 1; // ISO 4217
  int64 units = 2;          // Whole units
  int32 nanos = 3;          // Nano units (10^-9)
}

enum OrderStatus {
  ORDER_STATUS_UNSPECIFIED = 0;
  ORDER_STATUS_PENDING = 1;
  ORDER_STATUS_CONFIRMED = 2;
  ORDER_STATUS_SHIPPED = 3;
  ORDER_STATUS_DELIVERED = 4;
  ORDER_STATUS_CANCELLED = 5;
}

// Request/Response messages
message CreateOrderRequest {
  string customer_id = 1;
  repeated OrderItem items = 2;
  ShippingAddress shipping_address = 3;
}

message CreateOrderResponse {
  Order order = 1;
}

message GetOrderRequest {
  string order_id = 1;
}

message ListOrdersRequest {
  string customer_id = 1;
  int32 page_size = 2;
  string page_token = 3;
  OrderStatus status_filter = 4;
}

message ListOrdersResponse {
  repeated Order orders = 1;
  string next_page_token = 2;
  int32 total_count = 3;
}

// The Order Service
service OrderService {
  // Unary RPC
  rpc CreateOrder(CreateOrderRequest) returns (CreateOrderResponse);
  rpc GetOrder(GetOrderRequest) returns (Order);
  rpc ListOrders(ListOrdersRequest) returns (ListOrdersResponse);
  
  // Server streaming - watch order status changes
  rpc WatchOrder(GetOrderRequest) returns (stream Order);
  
  // Client streaming - bulk order import
  rpc BulkCreateOrders(stream CreateOrderRequest) returns (BulkCreateOrdersResponse);
  
  // Bidirectional streaming - real-time order updates
  rpc OrderUpdates(stream OrderUpdateRequest) returns (stream Order);
}

Generate Code

# Install protoc and plugins
brew install protobuf
go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

# Generate Go code
protoc --go_out=. --go_opt=paths=source_relative \
       --go-grpc_out=. --go-grpc_opt=paths=source_relative \
       proto/order_service.proto

# Generate Python code
pip install grpcio-tools
python -m grpc_tools.protoc -I. --python_out=. --grpc_python_out=. \
       proto/order_service.proto

Server Implementation

Go Server

package main

import (
    "context"
    "log"
    "net"
    "time"

    "google.golang.org/grpc"
    "google.golang.org/grpc/codes"
    "google.golang.org/grpc/status"
    "google.golang.org/protobuf/types/known/timestamppb"

    pb "github.com/mycompany/ecommerce/orders/v1"
)

type orderServer struct {
    pb.UnimplementedOrderServiceServer
    orders map[string]*pb.Order
}

func NewOrderServer() *orderServer {
    return &orderServer{
        orders: make(map[string]*pb.Order),
    }
}

// Unary RPC implementation
func (s *orderServer) CreateOrder(
    ctx context.Context,
    req *pb.CreateOrderRequest,
) (*pb.CreateOrderResponse, error) {
    // Validate request
    if req.CustomerId == "" {
        return nil, status.Error(codes.InvalidArgument, "customer_id is required")
    }
    if len(req.Items) == 0 {
        return nil, status.Error(codes.InvalidArgument, "at least one item is required")
    }

    // Calculate total
    var totalUnits int64
    for _, item := range req.Items {
        totalUnits += item.UnitPrice.Units * int64(item.Quantity)
    }

    // Create order
    order := &pb.Order{
        Id:         generateOrderID(),
        CustomerId: req.CustomerId,
        Items:      req.Items,
        Status:     pb.OrderStatus_ORDER_STATUS_PENDING,
        Total: &pb.Money{
            CurrencyCode: "USD",
            Units:        totalUnits,
        },
        CreatedAt: timestamppb.Now(),
        UpdatedAt: timestamppb.Now(),
    }

    s.orders[order.Id] = order

    return &pb.CreateOrderResponse{Order: order}, nil
}

// Server streaming implementation
func (s *orderServer) WatchOrder(
    req *pb.GetOrderRequest,
    stream pb.OrderService_WatchOrderServer,
) error {
    order, ok := s.orders[req.OrderId]
    if !ok {
        return status.Error(codes.NotFound, "order not found")
    }

    // Send initial state
    if err := stream.Send(order); err != nil {
        return err
    }

    // Simulate status updates
    statuses := []pb.OrderStatus{
        pb.OrderStatus_ORDER_STATUS_CONFIRMED,
        pb.OrderStatus_ORDER_STATUS_SHIPPED,
        pb.OrderStatus_ORDER_STATUS_DELIVERED,
    }

    for _, newStatus := range statuses {
        select {
        case <-stream.Context().Done():
            return stream.Context().Err()
        case <-time.After(2 * time.Second):
            order.Status = newStatus
            order.UpdatedAt = timestamppb.Now()
            if err := stream.Send(order); err != nil {
                return err
            }
        }
    }

    return nil
}

// Bidirectional streaming
func (s *orderServer) OrderUpdates(
    stream pb.OrderService_OrderUpdatesServer,
) error {
    for {
        req, err := stream.Recv()
        if err != nil {
            return err
        }

        order, ok := s.orders[req.OrderId]
        if !ok {
            continue
        }

        // Process update and send back
        order.UpdatedAt = timestamppb.Now()
        if err := stream.Send(order); err != nil {
            return err
        }
    }
}

func main() {
    lis, err := net.Listen("tcp", ":50051")
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }

    // Create server with interceptors
    server := grpc.NewServer(
        grpc.ChainUnaryInterceptor(
            loggingInterceptor,
            recoveryInterceptor,
            authInterceptor,
        ),
        grpc.ChainStreamInterceptor(
            streamLoggingInterceptor,
        ),
    )

    pb.RegisterOrderServiceServer(server, NewOrderServer())

    log.Println("gRPC server listening on :50051")
    if err := server.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}

Python Server

import grpc
from concurrent import futures
import time
from datetime import datetime

import order_service_pb2 as pb
import order_service_pb2_grpc as pb_grpc
from google.protobuf.timestamp_pb2 import Timestamp

class OrderService(pb_grpc.OrderServiceServicer):
    def __init__(self):
        self.orders = {}
    
    def CreateOrder(self, request, context):
        # Validate
        if not request.customer_id:
            context.abort(grpc.StatusCode.INVALID_ARGUMENT, "customer_id required")
        
        # Create order
        order_id = f"ORD-{int(time.time())}"
        total_units = sum(
            item.unit_price.units * item.quantity 
            for item in request.items
        )
        
        now = Timestamp()
        now.GetCurrentTime()
        
        order = pb.Order(
            id=order_id,
            customer_id=request.customer_id,
            items=request.items,
            status=pb.ORDER_STATUS_PENDING,
            total=pb.Money(currency_code="USD", units=total_units),
            created_at=now,
            updated_at=now
        )
        
        self.orders[order_id] = order
        return pb.CreateOrderResponse(order=order)
    
    def WatchOrder(self, request, context):
        """Server streaming - yield order updates"""
        order = self.orders.get(request.order_id)
        if not order:
            context.abort(grpc.StatusCode.NOT_FOUND, "Order not found")
        
        # Send initial state
        yield order
        
        # Simulate updates
        for new_status in [
            pb.ORDER_STATUS_CONFIRMED,
            pb.ORDER_STATUS_SHIPPED,
            pb.ORDER_STATUS_DELIVERED
        ]:
            time.sleep(2)
            order.status = new_status
            order.updated_at.GetCurrentTime()
            yield order
    
    def BulkCreateOrders(self, request_iterator, context):
        """Client streaming - receive multiple orders"""
        created_orders = []
        
        for request in request_iterator:
            response = self.CreateOrder(request, context)
            created_orders.append(response.order)
        
        return pb.BulkCreateOrdersResponse(
            orders=created_orders,
            total_created=len(created_orders)
        )

def serve():
    server = grpc.server(
        futures.ThreadPoolExecutor(max_workers=10),
        interceptors=[LoggingInterceptor()]
    )
    pb_grpc.add_OrderServiceServicer_to_server(OrderService(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    print("Server started on port 50051")
    server.wait_for_termination()

if __name__ == '__main__':
    serve()

Client Implementation

API Communication Photo by Markus Spiske on Unsplash

Go Client

package main

import (
    "context"
    "io"
    "log"
    "time"

    "google.golang.org/grpc"
    "google.golang.org/grpc/credentials/insecure"

    pb "github.com/mycompany/ecommerce/orders/v1"
)

func main() {
    // Connect with retry and load balancing
    conn, err := grpc.Dial(
        "localhost:50051",
        grpc.WithTransportCredentials(insecure.NewCredentials()),
        grpc.WithDefaultServiceConfig(`{
            "loadBalancingPolicy": "round_robin",
            "methodConfig": [{
                "name": [{"service": "ecommerce.orders.v1.OrderService"}],
                "retryPolicy": {
                    "maxAttempts": 3,
                    "initialBackoff": "0.1s",
                    "maxBackoff": "1s",
                    "backoffMultiplier": 2,
                    "retryableStatusCodes": ["UNAVAILABLE", "DEADLINE_EXCEEDED"]
                }
            }]
        }`),
    )
    if err != nil {
        log.Fatalf("failed to connect: %v", err)
    }
    defer conn.Close()

    client := pb.NewOrderServiceClient(conn)
    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()

    // Unary call
    resp, err := client.CreateOrder(ctx, &pb.CreateOrderRequest{
        CustomerId: "CUST-001",
        Items: []*pb.OrderItem{
            {
                ProductId:   "PROD-001",
                ProductName: "Widget",
                Quantity:    2,
                UnitPrice:   &pb.Money{CurrencyCode: "USD", Units: 29},
            },
        },
    })
    if err != nil {
        log.Fatalf("CreateOrder failed: %v", err)
    }
    log.Printf("Created order: %s", resp.Order.Id)

    // Server streaming
    stream, err := client.WatchOrder(ctx, &pb.GetOrderRequest{
        OrderId: resp.Order.Id,
    })
    if err != nil {
        log.Fatalf("WatchOrder failed: %v", err)
    }

    for {
        order, err := stream.Recv()
        if err == io.EOF {
            break
        }
        if err != nil {
            log.Fatalf("stream error: %v", err)
        }
        log.Printf("Order status: %s", order.Status)
    }
}

Advanced Patterns

Interceptors (Middleware)

func loggingInterceptor(
    ctx context.Context,
    req interface{},
    info *grpc.UnaryServerInfo,
    handler grpc.UnaryHandler,
) (interface{}, error) {
    start := time.Now()
    
    // Call the handler
    resp, err := handler(ctx, req)
    
    // Log after
    duration := time.Since(start)
    status := codes.OK
    if err != nil {
        status = grpc.Code(err)
    }
    
    log.Printf(
        "method=%s duration=%s status=%s",
        info.FullMethod,
        duration,
        status,
    )
    
    return resp, err
}

func authInterceptor(
    ctx context.Context,
    req interface{},
    info *grpc.UnaryServerInfo,
    handler grpc.UnaryHandler,
) (interface{}, error) {
    // Extract metadata
    md, ok := metadata.FromIncomingContext(ctx)
    if !ok {
        return nil, status.Error(codes.Unauthenticated, "no metadata")
    }
    
    // Validate token
    tokens := md.Get("authorization")
    if len(tokens) == 0 {
        return nil, status.Error(codes.Unauthenticated, "no token")
    }
    
    userID, err := validateToken(tokens[0])
    if err != nil {
        return nil, status.Error(codes.Unauthenticated, "invalid token")
    }
    
    // Add user to context
    ctx = context.WithValue(ctx, "user_id", userID)
    
    return handler(ctx, req)
}

Health Checks

import "google.golang.org/grpc/health/grpc_health_v1"

type healthServer struct {
    grpc_health_v1.UnimplementedHealthServer
}

func (s *healthServer) Check(
    ctx context.Context,
    req *grpc_health_v1.HealthCheckRequest,
) (*grpc_health_v1.HealthCheckResponse, error) {
    // Check dependencies
    if !isDatabaseHealthy() {
        return &grpc_health_v1.HealthCheckResponse{
            Status: grpc_health_v1.HealthCheckResponse_NOT_SERVING,
        }, nil
    }
    
    return &grpc_health_v1.HealthCheckResponse{
        Status: grpc_health_v1.HealthCheckResponse_SERVING,
    }, nil
}

gRPC-Gateway (REST Transcoding)

import "google/api/annotations.proto";

service OrderService {
  rpc CreateOrder(CreateOrderRequest) returns (CreateOrderResponse) {
    option (google.api.http) = {
      post: "/v1/orders"
      body: "*"
    };
  }
  
  rpc GetOrder(GetOrderRequest) returns (Order) {
    option (google.api.http) = {
      get: "/v1/orders/{order_id}"
    };
  }
}

Best Practices

Version your protos: Use v1, v2 packages
Use field numbers wisely: Never reuse deleted field numbers
Set deadlines: Always use context with timeout
Handle streaming errors: Check for io.EOF properly
Implement health checks: Required for Kubernetes deployments
Use interceptors: For cross-cutting concerns

Conclusion

gRPC is the modern choice for high-performance microservices communication. Its strong typing, efficient serialization, and native streaming support make it ideal for distributed systems. Combined with Protocol Buffers, you get a robust contract-first API development experience.

Start with simple unary RPCs, then explore streaming patterns as your needs grow. The investment in learning gRPC pays off in performance, reliability, and developer experience.

For more on microservices architecture, check out our guides on Kubernetes and observability with OpenTelemetry.

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