Microservices & Transport Standards

Priority: P0 (FOUNDATIONAL)

Microservices communication patterns and transport layer standards.

• •Synchronous (RPC): Use gRPC for low-latency, internal service-to-service calls.
  • •Why: 10x faster than REST/JSON, centralized .proto contracts.
• •Asynchronous (Events): Use RabbitMQ or Kafka for decoupling domains.
  • •Pattern: Fire-and-forget (emit()) for side effects (e.g., "UserCreated" -> "SendEmail").

Monorepo Architecture

• •Contracts:
  • •Pattern: Store all DTOs, .proto files, and Interfaces in a Shared Library (libs/contracts).
  • •Rule: Services never import code from other services. They only import from contracts.
• •Versioning: Semantic versioning of messages is mandatory. Never change a field type; add a new field.

Exception Handling

• •

  Propagation: Standard HttpException is lost over Rpc/Tcp.

• •

  Standard: Use RpcException and generic Filters.

  typescript

  // Global RPC Filter
  @Catch()
  export class RpcExceptionFilter implements RpcExceptionFilter<RpcException> {
    catch(exception: RpcException, host: ArgumentsHost): Observable<any> {
      return throwError(() => exception.getError());
    }
  }
  

Serialization

• •Message DTOs: Use class-validator just like HTTP.
  • •Config: Apply useGlobalPipes(new ValidationPipe({ transform: true })) in the MicroserviceOptions setup, not just HTTP app setup.