Quick Start

Quick Start

Let's begin with a Microservices example.

Use case

A business logic for user purchasing commodities. The whole business logic is powered by 3 microservices:

• Storage service: deduct storage count on given commodity.
• Order service: create order according to purchase request.
• Account service: debit the balance of user's account.

Architecture

StorageService

public interface StorageService {

    /**
     * deduct storage count
     */
    void deduct(String commodityCode, int count);
}

OrderService

public interface OrderService {

    /**
     * create order
     */
    Order create(String userId, String commodityCode, int orderCount);
}

AccountService

public interface AccountService {

    /**
     * debit balance of user's account
     */
    void debit(String userId, int money);
}

Main business logic

public class BusinessServiceImpl implements BusinessService {

    private StorageService storageService;

    private OrderService orderService;

    /**
     * purchase
     */
    public void purchase(String userId, String commodityCode, int orderCount) {

        storageService.deduct(commodityCode, orderCount);

        orderService.create(userId, commodityCode, orderCount);
    }
}

public class OrderServiceImpl implements OrderService {

    private OrderDAO orderDAO;

    private AccountService accountService;

    public Order create(String userId, String commodityCode, int orderCount) {

        int orderMoney = calculate(commodityCode, orderCount);

        accountService.debit(userId, orderMoney);

        Order order = new Order();
        order.userId = userId;
        order.commodityCode = commodityCode;
        order.count = orderCount;
        order.money = orderMoney;

        // INSERT INTO orders ...
        return orderDAO.insert(order);
    }

ER

storage

Property	Column	Type	Key
Storage ID	id	int	PK
Commodity Code	commodity_code	string	UK
Storage Count	count	int

order

Property	Column	Type	Key
Order ID	id	int	PK
User ID	user_id	string
Commodity Code	commodity_code	string
Order Count	count	int
Order Money	money	int

account

Property	Column	Type	Key
Account ID	id	int	PK
User ID	user_id	string	UK
Balance	money	int

SQL

DROP TABLE IF EXISTS `storage_tbl`;
CREATE TABLE `storage_tbl` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `commodity_code` varchar(255) DEFAULT NULL,
  `count` int(11) DEFAULT 0,
  PRIMARY KEY (`id`),
  UNIQUE KEY (`commodity_code`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `order_tbl`;
CREATE TABLE `order_tbl` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` varchar(255) DEFAULT NULL,
  `commodity_code` varchar(255) DEFAULT NULL,
  `count` int(11) DEFAULT 0,
  `money` int(11) DEFAULT 0,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `account_tbl`;
CREATE TABLE `account_tbl` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` varchar(255) DEFAULT NULL,
  `money` int(11) DEFAULT 0,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Distributed Transaction Solution with FESCAR

We just need an annotation @GlobalTransactional on business method:

    @GlobalTransactional
    public void purchase(String userId, String commodityCode, int orderCount) {
        ......
    }