challenge-14

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Challenge 14: Microservices with gRPC

In this challenge, you will implement a microservice architecture using gRPC concepts for service-to-service communication. You'll create a User service and a Product service that communicate to provide an order management system.

Learning Objectives

• Understand microservices architecture principles
• Learn gRPC concepts and error handling
• Implement service-to-service communication
• Practice with gRPC interceptors for cross-cutting concerns
• Handle network-based service interactions

Requirements

Implement the following TODO methods in solution-template.go:

1. Service Business Logic

• UserServiceServer.GetUser(): Retrieve user by ID with proper error handling
• UserServiceServer.ValidateUser(): Check if user exists and is active
• ProductServiceServer.GetProduct(): Retrieve product by ID with proper error handling
• ProductServiceServer.CheckInventory(): Check product availability

2. Order Service

• OrderService.CreateOrder(): Orchestrate user validation, product checking, and order creation

3. gRPC Infrastructure

• StartUserService(): Set up and start the user service with interceptors
• StartProductService(): Set up and start the product service with interceptors
• ConnectToServices(): Create clients and connect to both services

4. gRPC Clients

• UserServiceClient.GetUser(): Make gRPC calls to user service
• UserServiceClient.ValidateUser(): Make gRPC calls for user validation
• ProductServiceClient.GetProduct(): Make gRPC calls to product service
• ProductServiceClient.CheckInventory(): Make gRPC calls for inventory checking

5. Interceptors

• LoggingInterceptor: Log method calls and execution time
• AuthInterceptor: Add authentication metadata to requests

Key Concepts Covered

• gRPC Status Codes: Use appropriate status codes (NotFound, PermissionDenied, etc.)
• Service Interfaces: Clean separation between service logic and transport
• Network Communication: Real service-to-service calls
• Error Propagation: Proper error handling across service boundaries
• Interceptors: Cross-cutting concerns like logging and authentication
• Microservices Patterns: Service orchestration and coordination

Hints

• Use status.Errorf() to return proper gRPC errors
• Remember to handle both business logic errors and network errors
• Services should validate inputs and return appropriate error codes
• The OrderService orchestrates calls to both User and Product services
• Interceptors wrap all service calls for logging/auth

Running Tests

go test -v

The tests will:

1. Start individual services and test their functionality
2. Test service-to-service communication through OrderService
3. Verify proper error handling for various scenarios
4. Check that interceptors work correctly

Example gRPC Status Codes

• codes.OK: Successful operation
• codes.NotFound: Resource doesn't exist
• codes.PermissionDenied: User not authorized
• codes.ResourceExhausted: Insufficient inventory
• codes.InvalidArgument: Invalid input parameters

Complete all TODO methods to make the tests pass!