Seata

seata简介

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、SAGA和XA事务模式，为用户打造一站式的分布式解决方案。

微服务的分布式事务问题

传统的单片应用程序，它的业务有多个模块组成，使用单个本地数据源。本地事务将保证数据的一致性。

 

 微服务架构已发生变化，每个模块设计为单独的服务，每个服务有自己的数据库。本地事务自然可以保证每个服务中的数据一致性，但没办法保证整体业务数据的一致性。

 

 Seata分布式事务解决方案，分布式事务是由一批事务组成的全局事务，通常分支事务只是本地事务。

 

 

Seata术语：

• TC（Transaction Coordinator）事务协调者：维护全局和分支事务的状态，驱动全局事务提交或回滚。
• TM（Transaction Manager）事务管理器：定义全局事务的范围：开始全局事务、提交或回滚全局事务。
• RM（Resource Manager）资源管理器：管理分支事务处理的资源、与TC交谈以注册分支事务和报告分支事务的状态，并驱动事务提交或回滚。

 

 Seata管理的分布式事务的典型生命周期：

1，TM向tC申请开启一个全局事务，全局事务创建成功并生成一个全局唯一的XID。

2，XID在微服务调用链路的上下文中传播。

3，RM向TC注册分支事务，将其纳入XID对应全局事务的管辖。

4，TM向TC发起针对XID的全局提交或回滚决议。

5，TC调度XID下管辖的全局分支事务完成提交或回滚请求。

 

 Seata-Server的安装配置

1，下载安装，https://github.com/seata/seata/releases

2，修改seata/conf目录下的file.conf文件，先备份后修改。主要修改：自定义事务组名称+事务日志存储模式改为db+数据库连接信息。

## transaction log store, only used in seata-server
store {
  ## store mode: file、db、redis
  mode = "db"

  ## file store property
  file {
    ## store location dir
    dir = "sessionStore"
    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    maxBranchSessionSize = 16384
    # globe session size , if exceeded throws exceptions
    maxGlobalSessionSize = 512
    # file buffer size , if exceeded allocate new buffer
    fileWriteBufferCacheSize = 16384
    # when recover batch read size
    sessionReloadReadSize = 100
    # async, sync
    flushDiskMode = async
  }

  ## database store property
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp)/HikariDataSource(hikari) etc.
    datasource = "druid"
    ## mysql/oracle/postgresql/h2/oceanbase etc.
    dbType = "mysql" driverClassName = "com.mysql.jdbc.Driver" url = "jdbc:mysql://192.168.254.129:3306/seata" user = "root" password = "123.abc"
    minConn = 5
    maxConn = 100
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
    maxWait = 5000
  }

  ## redis store property
  redis {
    host = "127.0.0.1"
    port = "6379"
    password = ""
    database = "0"
    minConn = 1
    maxConn = 10
    maxTotal = 100
    queryLimit = 100
  }

}

3，Mysql创建数据库seata。

4，在seata数据库中建表，建表脚本在https://github.com/seata/seata/blob/develop/script/server/db/mysql.sql。

-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
CREATE TABLE IF NOT EXISTS `global_table`
(
    `xid`                       VARCHAR(128) NOT NULL,
    `transaction_id`            BIGINT,
    `status`                    TINYINT      NOT NULL,
    `application_id`            VARCHAR(32),
    `transaction_service_group` VARCHAR(32),
    `transaction_name`          VARCHAR(128),
    `timeout`                   INT,
    `begin_time`                BIGINT,
    `application_data`          VARCHAR(2000),
    `gmt_create`                DATETIME,
    `gmt_modified`              DATETIME,
    PRIMARY KEY (`xid`),
    KEY `idx_gmt_modified_status` (`gmt_modified`, `status`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(
    `branch_id`         BIGINT       NOT NULL,
    `xid`               VARCHAR(128) NOT NULL,
    `transaction_id`    BIGINT,
    `resource_group_id` VARCHAR(32),
    `resource_id`       VARCHAR(256),
    `branch_type`       VARCHAR(8),
    `status`            TINYINT,
    `client_id`         VARCHAR(64),
    `application_data`  VARCHAR(2000),
    `gmt_create`        DATETIME(6),
    `gmt_modified`      DATETIME(6),
    PRIMARY KEY (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(96),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_branch_id` (`branch_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

5，修改seata/conf目录下的registry.conf配置文件

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"
  loadBalance = "RandomLoadBalance"
  loadBalanceVirtualNodes = 10

  nacos { application = "seata-server" serverAddr = "127.0.0.1:8848" group = "SEATA_GROUP" namespace = "" cluster = "default" username = "" password = "" }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = 0
    password = ""
    cluster = "default"
    timeout = 0
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    cluster = "default"
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    application = "default"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    cluster = "default"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"

  nacos {
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    group = "SEATA_GROUP"
    username = ""
    password = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    appId = "seata-server"
    apolloMeta = "http://192.168.1.204:8801"
    namespace = "application"
    apolloAccesskeySecret = ""
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

6，启动nacos。

7，启动seata-server。点击seata/bin/seata-server.bat。