Md Mofijur Rahman

1// Distributed order microservice (Golang + gRPC)
2
3func (s *OrderService) CreateOrder(ctx context.Context, req *pb.CreateOrderRequest) (*pb.OrderResponse, error) {
4    // 1. Validate the incoming gRPC request payload
5    if err := s.validator.Validate(req); err != nil {
6        return nil, status.Errorf(codes.InvalidArgument, "invalid order: %v", err)
7    }
8
9    // 2. Persist to PostgreSQL via sqlc for type-safe, low-latency writes
10    order, err := s.queries.CreateOrder(ctx, db.CreateOrderParams{
11        ProductID:  req.ProductId,
12        CustomerID: req.CustomerId,
13        Quantity:   req.Quantity,
14        Price:      req.Price,
15    })
16
17    // 3. Publish "order.created" to Kafka for async downstream services
18    payload, _ := json.Marshal(order)
19    err = s.kafkaWriter.WriteMessages(ctx, kafka.Message{
20        Key:   []byte(order.ID.String()),
21        Value: payload,
22    })
23
24    // 4. Cache order state in Redis for fast, repeated reads
25    s.redis.Set(ctx, fmt.Sprintf("order:%s", order.ID), payload, time.Hour)
26
27    return &pb.OrderResponse{
28        OrderId: order.ID.String(),
29        Status:  "ACCEPTED",
30    }, nil
31}