分布式事务-seata AT模式-强一致性。

目录

1.seata原理

2.关键组件

3.seate服务端参数

4.微服务配置

5.业务流程

6.依次启动eureka、seate服务器、微服务

1.seata原理

    Seata 是一款开源的分布式事务解决方案，致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC(类似2PC)、SAGA（长事务解决方案、基于状态机），为用户打造一站式的分布式解决方案。

    AT模式同tx-lcn类似，通过代理底层数据库连接，控制数据库事务的提交与回滚（必须依赖数据库）；当然seate由于是由阿里维护的，同时支持多种注册中心，zookeeper、eureka等。

名词解释： TC 事务协调者、TM 事务管理器、RM 资源管理器、Microservices 微服务、DB 数据库

参考链接：

seate主项目:GitHub - seata/seata: Seata is an easy-to-use, high-performance, open source distributed transaction solution.

seate模板：seata-samples/springcloud-eureka-feign-mybatis-seata at master · seata/seata-samples · GitHub；

seate快速使用：Quick Start

2.关键组件

  eureka、seate-0.8.0服务端、微服务1(hello)、微服务2（feign-consumer）

  spring boot:2.1.8.RELEASE

  spring cloud:Greenwich.SR2

  代码链接：GitHub - kickTec/springCloudDemo at transaction-seate

  csdn链接：transaction-seate.rar-Java文档类资源-CSDN下载

3.seate服务端参数

主要指定host,多个网卡自动绑定IP有时不对

    @Parameter(names = "--help", help = true)
    private boolean help;
    @Parameter(names = {"--host", "-h"}, description = "The ip to register to registry center.", order = 1)
    private String host;
    @Parameter(names = {"--port", "-p"}, description = "The port to listen.", order = 2)
    private int port = SERVER_DEFAULT_PORT;
    @Parameter(names = {"--storeMode", "-m"}, description = "log store mode : file, db", order = 3)
    private String storeMode;
    @Parameter(names = {"--serverNode", "-n"}, description = "server node id, such as 1, 2, 3.it will be generated according to the snowflake by default", order = 4)
    private Long serverNode;
    @Parameter(names = {"--seataEnv", "-e"}, description = "The name used for multi-configuration isolation.",
        order = 5)

windows启动seate服务器

seata-server.bat -h 192.168.0.18

4.微服务配置

maven配置

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.8.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.kenick</groupId>
	<artifactId>feign-consumer</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>feign-consumer</name>
	<description>feign-consumer</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<!--数据库-->
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>2.0.0</version>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

		<!-- pageHelper分页插件 -->
		<dependency>
			<groupId>com.github.pagehelper</groupId>
			<artifactId>pagehelper</artifactId>
			<version>4.0.0</version>
		</dependency>

		<!--druid-->
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid-spring-boot-starter</artifactId>
			<version>1.1.10</version>
			<exclusions>
				<exclusion>
					<artifactId>slf4j-api</artifactId>
					<groupId>org.slf4j</groupId>
				</exclusion>
			</exclusions>
		</dependency>

		<!--lombok-->
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<version>1.18.8</version>
		</dependency>

		<!--seata-->
		<dependency>
			<groupId>com.alibaba.cloud</groupId>
			<artifactId>spring-cloud-alibaba-seata</artifactId>
			<version>2.1.0.RELEASE</version>
			<exclusions>
				<exclusion>
					<artifactId>seata-all</artifactId>
					<groupId>io.seata</groupId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>io.seata</groupId>
			<artifactId>seata-all</artifactId>
			<version>1.2.0</version>
		</dependency>

		<!--eureka client-->
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
		</dependency>

		<!--feign-->
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-openfeign</artifactId>
		</dependency>
	</dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

seate特殊配置（seate服务器和微服务指定相同的tx-service-group）：

spring.cloud.alibaba.seata.tx-service-group=my_test_tx_group

file.conf文件中设置：

  #transaction service group mapping
  vgroupMapping.my_test_tx_group = "default"
  #only support when registry.type=file, please don't set multiple addresses
  default.grouplist = "192.168.0.18:8091"

register.conf中指定使用eureka:

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "eureka"

  nacos {
    serverAddr = "localhost"
    namespace = "public"
    cluster = "default"
  }
  eureka {
    serviceUrl = "http://192.168.0.105:8888/eureka"
    application = "default"
    weight = "1"
  }

由于seate AT模式是通过代理数据库连接方式实现的，在每个service服务中都需要进行如下配置：

/**
 * 数据源代理
 */
@Configuration
public class DataSourceConfiguration {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource druidDataSource(){
        return new DruidDataSource();
    }

    @Primary
    @Bean("dataSource")
    public DataSourceProxy dataSource(DataSource druidDataSource){
        return new DataSourceProxy(druidDataSource);
    }

    @Bean
    public SqlSessionFactory sqlSessionFactory(DataSourceProxy dataSourceProxy)throws Exception{
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSourceProxy);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath:mybatis/mapping/*Mapper.xml"));
        sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
        return sqlSessionFactoryBean.getObject();
    }

}

全局事务使用，在service上添加注释

    @GlobalTransactional(name = "fsp-create-order",rollbackFor = Exception.class)
    @Override
    public int saveUser(String userId, String name, int age) {
        logger.debug("本地开始保存用户！");
        User user = new User();
        user.setUserId(userId);
        user.setName(name);
        user.setAge(age);
        int ret = userMapper.insert(user);
        logger.debug("本地开始保存用户结果:" + ret);

        logger.debug("开始远程调用helloservice!");
        String remoteRet = helloService.addUser("remote_hello" + userId, name, age);
        logger.debug("远程调用helloservice结果:" + remoteRet);

        // 产生异常
        // int num = 1/0;
        return ret;
    }

其它的请参考项目代码配置。

5.业务流程

    调用feign-consumer工程的addUser接口，接口逻辑：先在本地保存用户，再调用hello服务的保存用户接口，相当于一次调用保存2了个用户信息。

6.依次启动eureka、seate服务器、微服务

正常流程

调用feign-consumer接口（192.168.0.18:4001/addUser），先在当前服务添加用户，再调用另一个微服务hello添加用户；2个用户信息添加成功；全局事务执行情况见下图。

feign-consumer日志

hello日志

异常流程：两次用户都保存成功后，后续feign-consumer 服务异常，最终两个工程都进行了回退。

feign-consumer日志

hello日志