E-commerce microservices #1: what we are building, and the Gradle project skeleton

brew install git jq
brew install --cask docker
curl -s "https://get.sdkman.io" | bash
sdk install java 21-tem

ecommerce-platform/
├── api/                  # shared REST interfaces, DTOs, events
├── util/                 # global error handling, utilities
├── microservices/        # business services (from post 2)
├── spring-cloud/         # eureka, gateway, authorization-server (from post 11)
├── build.gradle
├── settings.gradle
└── gradlew

plugins {
    id 'java-library'
}

dependencies {
    api 'org.springframework.boot:spring-boot-starter-webflux'
    api "org.springdoc:springdoc-openapi-starter-common:${springdocVersion}"
    api 'com.fasterxml.jackson.datatype:jackson-datatype-jsr310'
}

package com.ecommerce.api.core.product;

import java.math.BigDecimal;

public record Product(int productId, String name, BigDecimal price, String serviceAddress) {
}

package com.ecommerce.api.core.product;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import reactor.core.publisher.Mono;

public interface ProductService {

    @GetMapping(value = "/product/{productId}", produces = "application/json")
    Mono<Product> getProduct(@PathVariable int productId);
}

package com.ecommerce.api.exceptions;

public class NotFoundException extends RuntimeException {

    public NotFoundException(String message) {
        super(message);
    }

    public NotFoundException(String message, Throwable cause) {
        super(message, cause);
    }
}

plugins {
    id 'java-library'
}

dependencies {
    api project(':api')
}

package com.ecommerce.util.http;

import java.time.ZonedDateTime;
import org.springframework.http.HttpStatus;

public record HttpErrorInfo(ZonedDateTime timestamp, String path, HttpStatus httpStatus, String message) {

    public HttpErrorInfo(HttpStatus httpStatus, String path, String message) {
        this(ZonedDateTime.now(), path, httpStatus, message);
    }
}

package com.ecommerce.util.http;

import static org.springframework.http.HttpStatus.BAD_REQUEST;
import static org.springframework.http.HttpStatus.NOT_FOUND;
import static org.springframework.http.HttpStatus.UNPROCESSABLE_ENTITY;

import com.ecommerce.api.exceptions.BadRequestException;
import com.ecommerce.api.exceptions.InvalidInputException;
import com.ecommerce.api.exceptions.NotFoundException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice
class GlobalControllerExceptionHandler {

    private static final Logger LOG = LoggerFactory.getLogger(GlobalControllerExceptionHandler.class);

    @ResponseStatus(BAD_REQUEST)
    @ExceptionHandler(BadRequestException.class)
    public HttpErrorInfo handleBadRequestExceptions(ServerHttpRequest request, BadRequestException ex) {
        return createHttpErrorInfo(BAD_REQUEST, request, ex);
    }

    @ResponseStatus(NOT_FOUND)
    @ExceptionHandler(NotFoundException.class)
    public HttpErrorInfo handleNotFoundExceptions(ServerHttpRequest request, NotFoundException ex) {
        return createHttpErrorInfo(NOT_FOUND, request, ex);
    }

    @ResponseStatus(UNPROCESSABLE_ENTITY)
    @ExceptionHandler(InvalidInputException.class)
    public HttpErrorInfo handleInvalidInputException(ServerHttpRequest request, InvalidInputException ex) {
        return createHttpErrorInfo(UNPROCESSABLE_ENTITY, request, ex);
    }

    private HttpErrorInfo createHttpErrorInfo(HttpStatus httpStatus, ServerHttpRequest request, Exception ex) {
        final String path = request.getPath().pathWithinApplication().value();
        final String message = ex.getMessage();
        LOG.debug("Returning HTTP status: {} for path: {}, message: {}", httpStatus, path, message);
        return new HttpErrorInfo(httpStatus, path, message);
    }
}

{
  "timestamp": "2026-10-02T05:57:56.405471652Z",
  "path": "/product/13",
  "httpStatus": "NOT_FOUND",
  "message": "No product found for productId: 13"
}

.gradle/
build/
!gradle/wrapper/gradle-wrapper.jar
.idea/
*.iml
.vscode/
out/
bin/
.DS_Store

./gradlew build

git add .
git commit -m "Post 1: Gradle multi-project skeleton with api and util modules"
git tag blog-01